Obsterics US

Basic Obstetric Ultrasound

Backgroun

The basic obstetric ultrasound examination provides an 

accurate and safe clinical assessment of 
the gravid uterus throughout a woman’s pregnancy including
 characterizing pregnancy location, 
identifying the number of embryos present, and aiding in the
 prenatal diagnosis of fetal anomalies 

In 2013, the American Institute of Ultrasound in Medicine (AIUM),
 in conjunction with the American 
College of Radiology (ACR) and the American College of
 Obstetricians and Gynecologists (ACOG), 
released updated Practice Guidelines for Performance of 
Obstetric Ultrasound Examinations. 
These guidelines describe the indications and key elements 
of 4 major types of obstetric ultrasounds, specifically :
 1.the first trimester US

2.standard second or third trimester US   

 3.and limited and specialized US examinations 
Further details regarding specific information gathered in each 
type of ultrasound exam is described below
Also see the article Targeted Obstetric Ultrasound.

Indications

First trimester ultrasound

The first ­trimester basic US is typically performed to confirm a 
viable intrauterine pregnancy. 
The exam may be performed either TA or trans-vaginally. 
It is ideally performed before 13 weeks and 6 days of gestation. 
US exam at this time aids in the clinical assessment of pelvic pain
  and/or vaginal bleeding
& vaginal bleeding in an early pregnancy because it can diagnose an

extrauterine pregnancy
 abnormal pregnancy, such as a A/hydatidiform molar pregnancy, 
an B/anembryonic gestation or
or an C/incomplete versus complete abortion.
A definitive diagnosis of an intrauterine pregnancy can be 

 made when 1. a (GS) gestational sac containing a 2.yolk sac (YS) 
   3. is visualized within the uterine cavity 

Without visualization of a YS or signs of a further developed pregnancy    

 such as an embryo, the location of the pregnancy cannot be certain

and further evaluation is warranted. 
In some cases where a pregnancy test is positive but there is no clear intrauterine pregnancy
 or extrauterine findings concerning for an ectopic pregnancy such
 as an adnexal mass on US, a
 patient may have a “pregnancy of unknown location.” 
It is important to consider the clinical context of a patient without a 

documented intrauterine pregnancy to guide further management. 
This includes the patient’s 1.pelvic pain 2.vaginal bleeding 3.Serial 
serum beta human chorionic gonadotropin levels (bHCG),3. and pelvic
 exam findings.
Additionally, a first trimester US is useful to diagnose an
 “early pregnancy loss” which 
is defined by American College of Obstetricians and 
Gynecologists as a 1. nonviable, 2. intrauterine pregnancy 
with 3. either an empty GS, OR a 4. GS containing an embryo 
or fetus without cardiac activity within the 1ST 12 & 6/7 weeks gestation.  
Society of Radiologists in US Multispecialty Panel on Early 1ST Trimester

diagnosis of Miscarriage and Exclusion of a Viable IUP have published conservative guidelines to aid with clinical judgment in the diagnosis
 of an abnormal intrauterine pregnancy. 
Diagnostic findings of an early pregnancy loss include:
1.) CRL of 7 mm or greater and NO heartbeat

2.) MSD of 25 mm or greater & NO embryo


3.) Absence of cardiac activity in an embryo 2 wks or more after 
a scan that showed a GS without a yolk sac, and/or
4.) the absence of cardiac activity in an embryo 11 days or more  

   after a scan that showed a GS with a YS sac.

Cardiac activity of an embryo is documented using 2-dimensional
 video clip or M-mode imaging
  If no cardiac motion is seen on TVS US in an embryo less than 7 mm,   

 a subsequent US in 1-2 wks is performed to assess for cardiac activity

 Additionally, if patient’s clinical presentation suggests a miscarriage i.e

heavy vaginal bleeding, but she is stable for expectant management,
 a follow-up US performed 7-14 days after initial presentation to assess

  for interval changes and viability is also appropriate management.

In the setting of a confirmed viable (IUP), the first ­trimester US 
utilized to provide an accurate gestational age (GA) assessment. 
IF only a GS and YS are visualized, the MSD is used to estimate GA
(Mean sac diameter (mm) + 30 = gestational age in days)
 However, if an embryo is visualized, then a (CRL) of the fetus should 
be used to determine an estimated due date because it is the 
most accurate measurement for establishing GA

  embryo should be seen by TVS US with a MGSD of 25 mm or greater. 
The CRL is the maximum length of the infant from cranium to caudal
 rump in a longitudinal plane. 

Measurements of the CRL are more accurate the earlier the first 
trimester US is performed. 
 If the CRL measurement is greater than or equal to 84 mm which corresponds to a GA of 14 & 0/7 wks, 2nd trimester biometric biometric parameters should be used for calculating the GA

 A reliable formula to calculate GA based on CRL is as follows:
 CRL (mm) + 42 days (+/- 3 days) = gestational age (days).  
https://emedicine.medscape.com/article/2047305-overview#a3

In 2014, ACOG published a standardized approach for calculating a patient’s anticipated due date 
using both US estimates and menstrual history, specifically the patient’s first day of the last menstrual 
period.  If the patient is unsure of her last menstrual period (LMP) or has a history of irregular 
menstrual cycles, dating should be calculated based on US measurements. 
In general, US dating is used when the discrepancy b/w menstrual dating and US dating is greater than the precision of ultrasonography. 
 First trimester calculations are more precise compared to later gestational ages. 
Before 14 0/7 weeks gestation, the mean CRL calculated has a precision (accuracy) of 5-7 days.

 Therefore, before 9 0/7 weeks gestation, the estimated due date should correspond to US measurements
 when there is more than a 5 day discrepancy between menstrual dating and US dating.

Similarly, if the US dating between 9 0/7 weeks gestation and 13 6/7 weeks gestation has more than
 a 7 day discrepancy from the menstrual dating, US measurements should be used to assign estimated 
due date. 
  In the second and third trimester, larger discrepancies reflect less precise measurements based on biometric parameters  .
In the setting of multifetal gestations, amnionicity and chorionicity should be documented. 
In the setting of desired genetic testing, nuchal translucency measurement aids in the screening 
assessment for fetal aneuploidy in conjunction with biomarkers. 
A first trimester US is also useful for the evaluation of maternal anatomy including assessment
 of the uterus, cervix and adnexal structures. The presence of adnexal masses, ovarian cysts, and/or leiomyomas should be documented and followed throughout pregnancy.

Second and third trimester ultrasound

Second or third trimester US examinations use fetal biometry to assess fetal growth and also can provide detailed information on fetal anatomy. 
A standard obstetric US exam also may include an evaluation of :
1. fetal presentation(s)

2. amniotic fluid volume

3. cardiac activity 

and placentation .4. 

After the first trimester, fetal biometry specifically measures the :
fetus’ biparietal diameter .1

2. head circumferences

 3.  abdominal circumference 
or average abdominal diameter
4. and femoral diaphysis length

 Fetal biometry may be utilized to establish an estimated due date for a pregnancy if no prior US 
measurement of the embryo was done. 
However the most accurate gestational age assessment is based on crown rump length measurement
 and the variability of gestational age estimations increases throughout pregnancy. 
For this reason, the earliest available US should always be used to assign an estimated due date
 and any significant discrepancies between gestational age and fetal measurements on subsequent 
ultrasounds should raise suspicion for growth abnormalities. 
The approximate error in fetal weight prediction methods is approximately 15% and is influenced 
by patient body habitus, weight range of fetus, technical factors such as machine quality and 
experience of ultrasonographer.  
In the third trimester, the femur length is the best single biometric measurement of gestational age.

Assessment of fetal anomalies, also known as a fetal anatomic survey, should be performed 
after 18 weeks gestational age and ideally performed between 18-20 weeks gestational age.

Although it may be possible to document anatomic structures before this time, the size, position,
 and movement of a fetus may limit a comprehensive examination of structures and therefore
 require repeat US examinations.

Additionally if a fetal anomaly is detected in this preferred gestational age window (18-20 weeks),
 termination of pregnancy may still be an option for the patient. 
The basic fetal anatomic examination includes assessment of the following structures: 
lateral cerebral ventricles .1

2. choroid plexus
3.   midline falx
4.  cavum septi pellucidi
5.  cerebellum
6.  cistern magna
7.  upper lip
8.  four-chamber view of heart
9. as well as left and right ventricular outflow tracts
10.  size and location of stomach
11.  urinary bladder and ureters
12.  spinal anatomy
13.  extremities
14.  and gender
. A more detailed anatomic survey may be indicated depending on the risk and concern for aneuploidy.
 The placenta should also be further characterized at this time, specifically noting its :
location .1

and proximity to the internal cervical os .2
3. as well as the number of vessels
4. and insertion site of the umbilical cord   

Additionally, the second and third trimester basic US may also be used to diagnose or to 
monitor maternal anatomical problems, most notably cervical length in the setting of risk factors for preterm birth or cervical insufficiency. 
US monitoring of fibroids and/or ovarian cysts is also important, but this is limited at later gestational
 ages due to the size of the gravid uterus.
https://emedicine.medscape.com/article/2047305-overview#a3

Limited and specialized ultrasound exam

A limited or specialized US may be performed at any gestational age and is typically used to evaluate
 a specific clinical concern during prenatal care. Some examples include assessment of cardiac
 activity when fetal heart tones are undetectable with external fetal monitoring devices to 
rule out fetal demise, notation of fetal presentation in setting of anticipated external cephalic 
version or to determine mode of delivery, and calculation of estimated fetal weight and amniotic fluid 
in setting of comorbidities that may predispose infants to growth abnormalities eg: chronic hypertension,
 pre-eclampsia, diabetes, multifetal gestation.  
Fetal growth evaluations are typically performed at 3-4 week intervals and usually include 
an assessment of amniotic fluid as well.

There are two main techniques to measure amniotic fluid in the second or third trimester, specifically 
single deepest pocket (SDP) OR the amniotic fluid index (AFI). 
The SDP technique records the 1. single 2.largest 3.vertical pocket of amniotic fluid 4.without 
evidence of umbilical cord or fetal parts visualized in utero. 
The AFI technique is the 1.summative measurement of the 2.single deepest vertical pocket of fluid 
without 3.evidence of cord or fetal parts noted 4.in all four quadrants of the uterus. 
Oligohydramnios 1.(or significantly low amniotic fluid), is defined as an 2.AFI less than 5 cm 
OR a 3.maximum vertical pocket less than 2 cm. 
 Polyhydramnios describes an abnormally large amount of fluid, is defined by:
 an 1.AFI greater than 24 cm OR a 2.single deepest vertical pocket (SDP) greater than 8 cm.

^#In multifetal gestations, fluid evaluation should be performed using the SDP technique. 
Comparison of measurement techniques show that measurement of the SDP leads 
to fewer interventions (such as induction of labor for oligohydramnios) with no increase in 
poor perinatal outcomes. 

Similar to a limited US exam, a detailed US exam is a supplemental tool to aid in the management 
of prenatal care in the setting of concern for 1.fetal well-being due patient history 2.genetic screening abnormalities, or results of prior US exams. For example, The CDC and ACOG recommend that 
pregnant women who live in or have traveled to areas with ongoing Zika virus exposure should 
undergo Zika virus serologic testing and fetal ultrasonography to screen for microcephaly 
or intracranial calcifications as early as 3-­4 weeks after symptoms or exposure . 
However, the CDC warned that fetal ultrasounds might not detect abnormalities until late second 
or early third trimester of pregnancy.

Other examples of specialized US exams include fetal surveillance with a biophysical profile, 
fetal Doppler US for assessment of placental insufficiency, and a more detailed anatomy scan or fetal echocardiography in setting of concern for fetal anomaly.

Safety

The prenatal US exam has been proven safe to both mothers and fetuses. As with any clinical
 test or medical intervention, a risk ­to ­benefit analysis of the test should be considered and should
 only be performed when there is a medical/obstetric indication or clinical concern. 
Additionally, if a diagnostic US is required for patient care it should be done under 
the “as low as reasonably achievable principle” (ALARA principle) due to possible risks associated
 to the physical effects from the exam including mechanical vibrations or increase in temperature 
under exam conditions as well as unknown risks of US energy to fetus not yet documented 
in the literature. Some ultrasonographic modalities, such as Doppler, deliver more energy to the area
 of interest and the use of those modalities should be reserved for specific clinical questions 
and an attempt made to limit their duration of use.
https://emedicine.medscape.com/article/2047305-overview#a3

Technical Considerations

Obstetric US examination requires real-time two-dimensional imaging via a trans-abdominal or 
trans-vaginal approach in order to adequately assess pregnancy viability through cardiac activity 
and fetal movement. 
There is currently no clinical evidence suggesting a clear advantage of three-dimensional imaging
 in prenatal diagnosis. 

The US TXR frequency must be selected to balance optimal beam penetration versus resolution,
 and therefore may vary based on a patient’s body habitus. For example, a lower-frequency TXR 
is beneficial in obese patients to allow for increased penetration and better imaging. 
Modern equipment typically includes a trans-abdominal transducer with 3 to 5 MHz frequency 
and a trans-vaginal transducer with 5-10 MHz frequency.

Modern US equipment has boundaries set by the manufacturer, limiting the fetal exposure to energy
generated by the equipment. 
As with any medical equipment, adequate care and maintenance should be performed as per 
manufacturer recommendations. 
Additionally, personnel involved with the use of US equipment should have appropriate training. 
Some US suites have quality ­assurance programs to evaluate performance of personnel and the US unit.
 The AIUM has published specific training guidelines for physicians who perform and interpret obstetric
 US which includes the following minimum requirements to demonstrate a strong knowledge base,
 technical skill and competency. Specifically for graduates of residency or fellowship programs to gain proficiency, the physician must perform at least 300 diagnostic ultrasounds.
 Additionally, a minimum of 170 annual diagnostic obstetric US exam is recommended to maintain
 the technical skills required for competency.

Procedure planning

Minimal preparation is required for a trans-abdominal or trans-vaginal US. 
A fasting state is not required, in contrast to other US studies (eg, GB ultrasonography).
 Some practitioners advise their patients to arrive to the US suite (compartment/wing) with a full bladder,
 but there is no consensus regarding this recommendation, especially for an obstetric US performed 
after 18 weeks’ gestation. 
If a trans-vaginal approach is to be used, the patient is asked to void just before the study to empty
 her bladder. This minimizes discomfort and collapses bladder for better visualization of pelvic organs.
US transducers require proper cleaning before and after each patient’s use to avoid risk of microbial transmission leading to infection. 
Transabdominal US transducers are typically cleansed with disposable antiseptic wipes and the 
clean transducer may be applied directly to the patient’s skin. 
Conversely, trans-vaginal US transducers require more extensive cleaning and sterilization. 
Specifically trans-vaginal transducers should be covered with a single-use disposal cover during 
the patient exam. 
After the exam is completed, cleaning steps include 1. removal of the disposal cover, 2. cleansing with running water or a damp cloth to remove residual gel or debris from probe, 3. followed by high-level disinfection chemical agents in accordance with FDA recommended guidelines. 
Periprocedural Care

Patient Education & Consent

Elements of informed consent

Most practitioners obtain verbal consent from patients. Ideally, this process should be initiated by the practitioner who requests the study. 
 The *Risks, *benefits, *expectations, and *limitations of the study should be presented. 
Some of the limitations relate to the *inability of an US to detect all fetal anomalies, *as well as the
 impossibility to rule out the risk of false-negative US results.
Additional consent is requested for transvaginal studies.

Equipment

The physics and principles involving US are complex, and the curious reader is encouraged to 
refer to other references for an in-depth discussion of those.
The most important part of the US machine is the transducer, the tool that makes contact with 
the patient’s skin. 
It is equipped with piezoelectric crystals that can 1. generate a sound pulse when excited by 
an electric current. That sound is 2. released at a specific frequency, 3. travels through human tissue,
  .and 4. interacts with it based on physical properties of the tissue. 
Sound is 5. absorbed by the tissue, and 6. reflected back to the transducer, where the piezoelectric 
crystals 7. change that message to electrical impulses that are 8. sent to the processor for interpretation.
 The 9. processing unit interprets the signals and creates the image we see on the screen.

Patient Preparation

For all diagnostic US studies and most, if not all, US-assisted procedures (eg, amniocentesis), 
anesthesia is not required.

Positioning

For abdominal studies, the patient is in a 1. supine position for most of the study, 
with the 2. abdomen uncovered to provide skin contact with the US TXR. 
She 3. may keep their clothes on. 
A 4. coupling gel is used b/w the TXR and the skin to reduce acoustic impedance from environmental air

 This gel may be warmed for patient comfort.
For transvaginal studies, the patient is to 1. remove clothing from the lower part of her body
 and to 2. lie in a dorsal lithotomy position. Regular stirrups may be used to assist with positioning,
 or the patient may be asked to assume a frog-leg position.
 The 3. pelvic area is covered by a blanket for the patient’s comfort. 
The transvaginal probe is 1. covered with a coupling gel, and 2. a vinyl or latex cover is then
 placed around the transvaginal US probe. 3. Another layer of gel is applied around the covered probe to *assist in the vaginal insertion and to *reduce the acoustic impedance.
Some patients may feel that they are more “in control” of a transvaginal examination if they
 insert the vaginal probe themselves. 
Personnel involved in performing transvaginal studies need to be sensitive to patient’s requests.
Technique

Approach Considerations

An abdominal approach is acceptable for most first- and second-trimester US examinations.
In some cases, such as those involving 1. maternal obesity,2. abdominal scars due to prior surgeries,3. close evaluation of the cervical length during the second trimester, or 4. gestation less than 8 weeks, 
a transvaginal or translabial approach may be used. The US probe used with this approach 
is smaller to gain access through the vagina. 
In addition, the sound frequency that the probe emits is higher, as the target is closer to the probe.
In general, nuchal translucency evaluation during the first trimester may be accomplished with the transabdominal approach.
https://emedicine.medscape.com/article/2047305-technique

Technique contd

First-Trimester Ultrasound

Approach to a first-trimester ultrasound

The first-trimester US exam is used mainly to confirm:
1. intrauterine pregnancy (IUP),
2. to confirm dating
 an to 3. assess nuchal translucency. 
The uterus, cervix, and adnexa should be evaluated for 1. location of a GS. 2. If a GS
is seen, the presence or absence of yolk sac should be reported.
Discriminatory levels of human chorionic gonadotropin (hCG) and US findings have been reported. 
Those are quantitative levels of the pregnancy hormone beta–human chorionic gonadotropin (b-hCG)
 and expected US findings in a viable pregnancy. 
They may help predict the viability of Intrauterine Pregnancies with Uncertain Viability (IPUV).
Table 1. Mean Gestational Sac Sizes at Which a Yolk Sac and an Embryo Should Be Visible 

  Yolk sac should be visible By TVS :
 When MSD is 8 mm (BUT 20 mm By TAS) & when b-hCG is 7200 mIU/mL when GA is 5-6 wks
Embryo should be visible By TVS :
When MSD is 16 mm (BUT 25 mm By TAS) & when b-hCG is 10.000 mIU/mL when GA is

more than 6 wks
The YS can usually be visualized if the GS is approximately 1 cm in diameter. 
In some cases of embryonic demise, the yolk sac is deflated or irregular.
Fetal *number, *location,*presence & *heart rate should be clearly evaluated and documented. 
An attempt to determine chorionicity should start during the first-trimester ultrasound. 
Thick interfaces b/w gestational sacs suggest dichorionic pregnancies, & thin or absent membranes 
likely represent monochorionic twins.
A corpus luteum cyst (CLC) may be observed in the maternal adnexa, usually 3 cm or less in diameter. 
Both adnexa should be evaluated for the presence of large ovarian cysts such as occurs in ovarian hyperstimulation syndrome, & solid masses such as in ovarian neoplasm. 
The uterus should also be evaluated for *homogeneity, *presence, *size & *location of fibroids, especially intracavitary.

Embryonic demise

The first-trimester US presents an opportunity to identify some problematic pregnancies. 
Early signs of nonviable pregnancies include a *GS with an irregular shape or one that is *not growing 
or *b-hCG levels not correlating with ultrasonographic findings. 
Embryonic demise may be diagnosed when the *CRL is 6 mm without fetal cardiac activity.
A study found that current guidelines regarding ultrasonographic diagnosis of 

miscarriage may still be associated with misdiagnoses and should be 
updated to take into account gestational age.

Ectopic pregnancy

Ectopic pregnancies or {Heterotopic} pregnancies, describe (one fetus inside the uterine cavity 
while another fetus is implanted outside the uterine cavity) may also be diagnosed. 
Clinically, ectopic pregnancy may manifest as 1. pelvic pain and/or 2. vaginal bleeding, 3. elevated
 b-hCG levels 4. free fluid in the peritoneal cavity usually representing blood, and adnexal findings.

Anencephalia

Severe fetal anomalies can also be diagnosed in the first trimester.
Anencephalic fetuses present with an absent cranium on this early ultrasound examination.

First-trimester sonographic markers for aneuploidy

Aneuploidy is the presence of an abnormal number of chromosomes in a cell, for example 
a human cell having 45 or 47 chromosomes instead of the usual 46. It does not include a 
difference of one or more complete sets of chromosomes. 
A cell with any number of complete chromosome sets is called a euploid cell.

 
(AN-yoo-PLOY-dee)
 Is the occurrence of one or more extra or missing chromosomes in a cell or organism. 
Aneuploidy refers to any chromosome number that is not an exact multiple of the haploid number of chromosomes (which is 23 in humans).
Early tests for aneuploidy include 
the 1. measurement of the skin swelling behind the fetal neck 
 the (nuchal translucency), along with two biochemical markers :

2. pregnancy-associated plasma protein A (PAPP-A) and

3. free-hCG.

  Other 4. anatomical markers for aneuploidy on the first-trimester US include :

*the absence of nasal bone 

*increased frontomaxillary angle measurement based on GA 

*the appearance of an objective decrease in blood flow during an atrial contraction.
 on ductus venosus Doppler evaluation (a-wave abnormalities)

* increased tricuspid valve regurgitation.

 * a-wave abnormalities
However, not all of these markers can currently be assessed in the general population.

First-trimester screening has a detection rate of 87% for aneuploidy.
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Technique contd

Second- and Third-Trimester US Evaluation

Approach 

The most common indication for a second-trimester US examination is evaluation of fetal anatomy, 
usually b/w 18 and 20 weeks’ gestation. 
At this point, 1. the embryologic period is well passed, and 2. fetal organs are, for the most part,
 easily visualized and evaluated.
The embryologic period describes the 1ST 8 weeks of fetal development, (wk 3 to which are characterized by the growth and differentiation of tissues into organs 
 . This process is known as organogenesis and occurs from weeks 3 through 8, (embryonic period).
 Fetal *position, *early pregnancy, *anterior placenta, *multiple pregnancies, *uterine fibroids,

 and *maternal obesity, may impede a good anatomical evaluation of the fetus at this stage . 
If the exam is inconclusive because of one of these factors, the patient may be asked to return 
to finalize the fetal anatomical evaluation at a later date.

Embryo at 12 weeks' gestation.

In some cases, owing to choice or lack of early access to prenatal care, patients are unable to obtain
 an early US examination to confirm the *gestational age (GA) of the pregnancy, *number of fetuses,
 and *chorionicity, which can be determined with a second-trimester ultrasound.
While a first-trimester US is considered a better tool for gestational dating, the second-trimester US 
can be used to determine GA. A composite of multiple fetal measures is made and averaged. 
The common practice is not to override dates based on the calculation of last menstrual period 
unless there is a difference of 5 days between dates determined by last menstrual period and 
first-trimester US or a difference of 10 days between the last menstrual period and second-trimester US.

Multiple pregnancies

Evaluation of fetal chorionicity when multiples are present, may be performed similarly as on the 
first-trimester ultrasound. 
If the fetuses are located in 1.different gestational sacs and the 2.membrane dividing the fetuses is *thick 
and has a *broad base, the pregnancy is more likely dichorionic. 
Conversely, if the membrane dividing the twins is *thin *without a broad base,
 called a *(twin peak) or {delta sign}, or *absent it suggests a monochorionic pregnancy.      
    If the fetuses are *different sexes, *dichorionic pregnancy is diagnosed.

Placental evaluation

If the patient presents with acute vaginal bleeding, ultrasound may help determine cause. 
Placenta previa occurs when part or the entire placenta covers the internal cervical os. This diagnosis is important, as it requires cesarean delivery.

Abruptio placentae refers to early separation of part or the complete placenta. A hypoechoic area may 
be seen on the interface between the uterus and the placenta. 
Vasa previa is rarer and is diagnosed by visualizing placental blood vessels running across the 
internal cervical os.
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 Technique contd
Fetal ultrasound testing
Fetal well-being may be evaluated with various measures.
A biophysical profile (BPP) is composed of a series of measurements to assess fetal hypoxia.
They include : 1.amniotic fluid evaluation 2.breathing movement 3.gross body movements,
 and 4.fine movement.
A scoring system consisting of either 0 or 2 points is then applied to the fetal evaluation.
Measurement of the fetal umbilical artery (UA) Doppler, indicateis the resistance that fetal blood
 flow finds at the placental level.
To obtain fetal UA Doppler, the angle of insonation should be as close to zero degrees to the umbilical
 artery as possible.
A comparison of forward blood flow b/w fetal systole and diastole is obtained.
A large systolic-to-diastolic ratio indicates higher resistance of blood flow at the placental level.
Maternal anatomy to be evaluated includes the *uterus, *adnexa and *cervix

Fetal structures to be evaluated include the *head *face *neck *cerebellum *choroid plexus
 cisterna*magna *lateral cerebral ventricles *midline falx *cavum septi pellucidi & *upper lip.
Most of the fetal syndromes, aneuploidies, and severe fetal anomalies manifest as fetal CNS anomalies.
 A normal US finding does not completely rule out fetal aneuploidies but is reassuring.
 If the patient had a prior pregnancy complicated by CNS anomalies, the risk of recurrence in a later pregnancy is about 2%.

Fetal growth

Similarly, by following the same parameters measured to obtain GA on the second-trimester US, the pregnancy may be monitored for objective estimation of fetal growth. 
Clinically, fetal growth is monitored by measuring the fundal height during routine obstetric visits. 
Fetal measurements obtained to determine fetal age and weight include :*biparietal diameter
  head *circumference *abdominal circumference *femur length *humerus length. 
When growth of fundal height is not as expected in some twin pregnancies or others pregnancies 
at risk for growth restriction, serial second- and third-trimester ultrasounds may be performed
 to evaluate adequate fetal growth. 
Because of variability in US measurements, a 3-week wait between growth ultrasounds is used to determine fetal growth.
Fetal head circumference should be measured in a plane that includes the 
cavum septum pellucidum, falx cerebri, and thalamus. 
To measure the biparietal diameter (BPD), the calipers should be placed from the outside
 of the calvarium proximally to the inside of the calvarium distally, crossing the falx cerebri 
at a 90° angle.
The same anatomical landmarks used to measure the biparietal diameter are used to measure the
 fetal head circumference. 
This measurement is obtained by measuring the outer circumference formed by the calvarium. 
Head measurements may be helpful to indicate *fetal age, *microcephaly, or *macrocephaly.
Objectively, the cephalic index (CI) is defined as the width of the head divided by the length in a percentage scale. 
The normal value is b/w 70 and 80, but an abnormal value does not necessarily indicate pathology. 
If the cephalic index is more than 80, the fetal head will have a rounded appearance, also called brachycephalia & may be seen in trisomy 18.
 If the cephalic index is less than 70, the head may appear flat, also known as dolichocephalia 
& may be seen is preterm babies or craniosynostosis. 
Minor changes in the shape of the fetal head are normal. 
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 Technique contd

Fetal anatomy: CNS

The cerebellum is located in the posterior inferior aspect of the brain. It has a large mass of cerebral 
cortex above and the Pons below. 
It is divided in two hemispheres. The cerebellar surface folds into itself, increasing the area. 
Those folds are called lobules. 
There are 3 major areas: the *flocculonodular, *anterior, and *posterior lobes. This organ has more 
neurons than the rest of the brain. 
The functions are related to *gait, *language, and *body tone. Fetal evaluation of the cerebellum 
includes its *presence *shape and *size. During a second-trimester US, cerebellum is measured by the 
outer length of the posterior cerebellar hemispheres, at the same plane that the septum cavum pellucidum, cisterna magna, and nuchal fold are seen.
Posterior fossa deformities are seen with Chiari II malformations (also called Arnold-Chiari), in which parts
 of the cerebellum and brainstem are pulled downward into the foramen (ovale ???? magnum) owing to a 
spinal defect. The sonogram shows obliteration of the posterior fossa structures, usually with elongation of the 
cisterna magna (banana sign) and flattening of the frontal cephalic bones (lemon sign).
The cisterna magna is also located in the posterior fossa, posterior to the cerebellum. It is part of 
the openings of the subarachnoid space. 
Dilatation of the cisterna magna may occur in conditions such as Dandy-Walker malformation, in which 
there is an abnormal *communication b/w the fourth ventricle and the cisterna magna *via a defect in the cerebellar vermis.
The human brain has 4 choroid plexus. They are built as a *filter b/w the *blood and the cerebrospinal 
fluid *(CSF) and consist of *many blood vessels separated from the ventricular space by *choroid epithelial cells that, by *passive and active transport, *maintain the balance of the cerebrospinal fluid. They are 
located in the *superior horn of the lateral ventricles. On US, they appear as a *bright half-moon–shaped 
echo area in the ventricle. *Choroid plexus cysts are found in 1 per 100 fetuses with trisomy 18; however, 
if the only abnormal finding is a choroid plexus cyst, the risk for trisomy 18 is 1 in 477.
The American College of Obstetricians and Gynecologists (ACOG) recommends considering amniocentesis 
if there are other “soft” markers for aneuploidy, if the blood markers for aneuploidy are abnormal, or if the mother will be aged 32 years at the time of term delivery. 
A choroid plexus that is *floating in the lateral ventricle is called a floating or “drooping” choroid,

which is *caused by an enlarged lateral ventricle
The ventricular system of the brain is composed of the *lateral ventricles, the*third and the *fourth ventricles. Cerebrospinal fluid (CSF) is produced by *blood *filtered by *ependymal cells on the *choroid plexus. 
CSF travels along all ventricles to be reabsorbed through the arachnoid villi

During second-trimester US, the lateral ventricles are measured in a plane where the cavum septum 
pellucidum is visible anteriorly, from the internal membranes of the lateral ventricles just behind the 
choroid plexus. A blockage from the reabsorption system may cause an enlarged lateral ventricle, 
with increased CSF pressure, which is called ventriculomegaly, a condition seen with hydrocephalus. 
If the cause of the hydrocephalus is not evident, it is called simple hydrocephalus. In some cases, 
hydrocephalus may occur along with other conditions such as Dandy-Walker malformation or agenesis
 of the corpus callosum.
The cavum septum pellucidum (CSP) is composed of *two different layers of gray and white matter. 
The*space b/w the two layers is the cavum, which *disappears during adult life. It is *closely related 
to the corpus callosum.*Absence of the cavum on a second-trimester US may indicate absence of the 
corpus callosum, which may be *associated with multiple syndromes, including *trisomy 13 or *18 or 
Dandy-*Walker malformation. Agenesis of the corpus callosum may be confirmed with ultrasound of the midcoronal planes.

Fetal anatomy: SPINE:

The spinal evaluation of the fetus begins with an anatomic assessment of the head, abnormalities of which
 reflect some spinal problems. 
For instance, Chiari II malformations are often seen in fetuses with spina bifida. Owing to the decreased 
pressure in the spine, contents of the posterior fossa herniate through the foramen magnum into the spinal canal. 
There is displacement of the cerebellar vermis, fourth ventricle, and medulla oblongata. The cistern magna enlarges, becoming banana-shaped. The frontal bones collapse and the head may take on a lemon shape.
The most common spinal anomalies are the ones associated with spina bifida, in which failure of the 
vertebral bones to close allows part of the spinal cord to lie outside the neural canal. 
In cases of spina bifida occulta, the vertebral schisis (split/cleft) is covered with skin, and 
it may appear as a lipoma or dimple at birth. 
If the defect is open, it is referred as a spina bifida aperta, and it is further classified as a meningocele
  if it is covered by a thin meningeal membrane  or myelomeningocele (if the sac contains neural tissue).
The International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) recommends that, when 
possible, a longitudinal section of the fetal spine should be obtained to screen for open and closed spinal dysraphism (spina bifida). 
Targeted fetal neurosonography is recommended if there is suspicion of a brain or spinal abnormality during
 the obstetric ultrasound examination.

Fetal anatomy: Chest

The fetal chest evaluation includes the fetal heart and lungs. The chest view should include 
a 4-chamber heart and outflow tracts, if possible. 
A detailed cardiac US is beyond the scope of this article and is reserved for patients with a prior history  

of a fetus with *cardiac anomalies, patients with *overt diabetes, suspicions of a *syndrome that affects 
the fetal heart, and patients with *abnormally appearing fetal cardiac anatomy based on second-trimester ultrasound.
In the evaluation of the fetal heart, the position of the fetal heart in relation to the fetal body should 
be assessed first. The fetal stomach and the apex of the fetal heart should be on the left side of the fetus.
Next, a 4-chamber view of the fetal heart should be obtained. 
The transverse view of the fetal heart is obtained right above the fetal diaphragm. 
With minor adjustments, a 4-chamber view is acquired. 
The apex should be pointing to the left side, and the right ventricle should be the most anterior chamber. 
The upper chambers should be equal in size to the lower chambers, and both sides should be of similar 
size during both systole and diastole. 
This view allows the sonographer to evaluate the interventricular septum. The size of the heart should 
be about half the size of the whole thorax.

Movement evaluation during this view includes free movement of both atrioventricular valves, 
as well as the foramen ovale flap in the left atrium. In some cases, an echogenic intracardiac focus that represents calcifications on the papillary muscle is seen and is a marker for fetal aneuploidy. 
With this view, more than half of the congenital cardiac anomalies may be detected, including those 
related to cardiac position, cardiac septa, cardiac chambers, and masses. 
Left outflow and right outflow views may be obtained, if possible.
Additional cardiac views may be obtained for a more complete fetal cardiac evaluation. 
These include the long axis of the left ventricle, short axis of the great vessels, aortic arch, and pulmonary
 artery view.
Fetal heart tones may be visible as early as 5 weeks’ gestation. The 5 components of the fetal heart 
motion to be evaluated include rate, rhythm, atrioventricular association, structural anomalies, and
 evaluation for hydrops. The fetal heart rate may change during the course of the pregnancy but should
 generally be between 110 and 180 beats per minute. 
Routinely, an M-mode picture of the fetal heart is taken. Fetal heart rhythm may be constant or variable; 
minor variability is normal, but significant rate variability should be noted, and, if the fetus is viable,
 the obstetrician should be notified immediately.

Fetal heartbeat at 20 weeks' gestation.

https://emedicine.medscape.com/article/2047305-technique?icd=login_success_email_match_norm&icd=login_success_email_match_norm#c3

Technique contd

Fetal anatomy:diaphragm   

The fetal diaphragm is evaluated for continuity. Congenital diaphragmatic hernia is the most common
 anomaly in the fetal thorax if cardiac problems are excluded. 
They are difficult to observe with US tend to grow as the pregnancy progresses. 
The diagnosis may be made upon observation of *loops of bowel in the thorax or *discontinuity of the 
diaphragm muscle.
Cysts in the region of the lungs may result from cystic adenomatous hyperplasia or bronchopulmonary sequestration. There is hamartomatous involvement in cystic adenomatous hyperplasia, and the 
prognosis depends on the size and type. 
In bronchopulmonary sequestration, a portion of the bronchopulmonary system develops separately
 and is seen as a hyperechoic area at the lung base.

Fetal anatomy: Abdomen

Components of the abdominal-area evaluation should include  : *presence *size *position and 
of *the stomach *kidneys *bladder *umbilical cord insertion site into the fetal abdomen *and umbilical 
cord vessels.
The plane for abdominal circumference should include : the outer margins of a transverse plane that includes the fetal *stomach,*spine *liver and the *umbilical portion of the left portal vein equidistant 
from both sides of the abdomen. 
A small circumference may indicate a growth-restricted fetus. The fetal liver can be evaluated *for 
size and presence of *masses or *cysts. 
Liver calcifications have been described as part of fetal viral infections. 
A “double-bubble” stomach indicates duodenal atresia, a marker for Down syndrome. 
Absence of the fetal stomach may be related to other fetal anomalies.
Esophageal atresia may be diagnosed with 1.US based on the absence of a visible fetal stomach and
 the presence of 2.polyhydramnios; however, the diagnostic yield with US is only about 50%. 
Bowel dilatation may indicate 1.large-bowel obstruction or 2.anal atresia. 
Hyperechoic bowel is seen in cases of 1.meconium, 2.bleeding or 3.cystic fibrosis.
Two anterior abdominal defects are worth mentioning  : 1.Omphalocele is a *midline defect *covered 
by a *membrane. If the defect is large enough, it may include the fetal liver. *The association with fetal syndromes is high. 2.Gastroschisis is *a lateral defect to the umbilical cord, *NOT covered by a membrane.
 On *US, it is visualized as free loops of bowel in the amniotic sac. It has been *associated with some fetal syndromes, but at a lower rate than omphalocele.
Fetal kidneys are located *on both sides of the fetal spine, with an *ovoid shape in a longitudinal view 
and a round shape in a transverse view. Fetal kidneys *enlarge with GA; therefore, they are easier to
 visualize as pregnancy progresses and the fetus grows. It is not routinely necessary to measure the kidneys. Care should be *taken in NOT confuse the fetal adrenal gland as part of the kidneys, as it may be larger 
than in adults. *Minor fluid collection in the kidneys is normal, BUT more than 4 mm before 32 weeks’ gestation OR more than 7 mm after 32 weeks’ gestation fluid collection (pyelectasis) may be a marker of aneuploidy.
In fetuses who present with obstruction of the renal outlet, the affected kidney is visualized on US *as a paraspinal sac *cysts or *abnormal ureteral dilatations. 
Absence of kidneys is rarer but carries a lethal prognosis. 
Polycystic kidneys are a *bilateral disorder *representing tubular ectasia, usually *appearing after the 
second trimester. 
Meckel-Gruber syndrome is characterized by 1.polycystic kidneys with 2.encephalocele and 3.polydactyly.
Fetal bladder is 1.seen as a hypoechoic area 2.caudally on the fetus. The 2.filling cycle of the bladder is  60-90minutes; therefore if an initial view of the fetus does not demonstrate a bladder, repeat imaging is recommended. 
In rare cases such as in urinary obstruction, the identification of fetal sex is medically indicated.
The umbilical cord may be evaluated by applying color Doppler interrogation to the area around the 
bladder and visualizing the two umbilical arteries around the bladder. 
Care should be taken to obtain a transverse view of the fetal abdomen and not to confuse the fetal
 iliac arteries.

Fetal anatomy: Extremities

The *presence or *absence of fetal extremities should also be documented. This is done *by demonstrating one bone in the proximal extremity and two bones distally. Measurement of *the long bones is obtained to evaluate fetal growth.
A single-center study by Dicke et al indicated that although US exam allows most cases of abnormal hand position, limb reduction defect, and arthrogryposis to be detected prenatally, at least 20-25% of these abnormalities will probably be missed. 
Arthrogryposis describes congenital joint contracture in two or more areas of the body. It derives its name from Greek, literally meaning 'curving of joints'.
The sensitivity of US was found to be as follows  :
Polydactyly: 19.1%
    Abnormal hand position: 76.0%
    Limb reduction defect involving the long bones: 76.1%
    Arthrogryposis: 81.3%
https://emedicine.medscape.com/article/2047305-technique?icd=login_success_email_match_norm&icd=login_success_email_match_norm#c3

Second Stage of Labor
The second stage of labor 1/commences with complete cervical dilation to 10 centimeters and ends 

with the delivery of the neonate. This was also defined as the pelvic division phase by Friedman. 
After 2/cervical dilation is complete, the fetus 1.descends into the vaginal canal with or without maternal 
pushing efforts. The 2.fetus passes through the birth canal via 7 movements known as the cardinal movements : A/engagement B/descent C/flexion D/internal rotation E/extension F/external rotation
 and G/expulsion.

In women who have delivered vaginally previously, whose bodies have acclimated to delivering a fetus,
 the second stage may only require a brief trial, whereas a longer duration may be required for a nulliparous female. 
In parturients (giving birth) 3/without neuraxial anesthesia, the second stage of labor typically lasts
 less than three hours in nulliparous women and less than two hours in multiparous women. 
In women 4/who receive neuraxial anesthesia, the second stage of labor typically lasts less than 
four hours in nulliparous women and less than three hours in multiparous women.

If the second stage of labor lasts longer than these parameters, then the second stage is 
considered prolonged. 
Several elements may influence the duration of the second stage of labor, including fetal factors
 such as fetal *size and position, or maternal factors such as *pelvis shape, the *magnitude of
 expulsive efforts *comorbidities such as hypertension or diabetes *age, and history of *previous deliveries.
 https://www.ncbi.nlm.nih.gov/books/NBK544290/

Third Stage of Labor
The third stage of labor commences when the 1.fetus is delivered and concludes with the 2.delivery of the placenta. 
Separation of the placenta from the uterine interface is hallmarked by three cardinal signs, including :
a 1.gush of blood at the vagina 2.lengthening of the umbilical cord & a 3.globular shaped uterine fundus on palpation.
Spontaneous expulsion of the placenta typically takes between 5 to 30 minutes. 
A delivery time of greater than 30 minutes (Retained Placenta), is associated with a higher risk of :
 post 1.partum hemorrhage and may be an indication for 2.manual removal or other 3.intervention. 
Management of the third stage of labor involves 1.placing traction on the umbilical cord with 2.simultaneous 
fundal pressure to effect faster placental delivery.
 The function of the stages of labor is to create a universal definition that medical professionals can 
use to communicate with each other about labor. 
The stages of labor can be used to help determine where the patient is on the labor spectrum. 
Clarifying the stages of labor has helped create guidelines, which define normal and abnormal trends
 in labor. Clinical management also gears toward the various stages of labor.
Complications may arise during any of the stages of labor to result in abnormal labor. 
During the first stage, women may experience the arrest of parturition, necessitating cesarian delivery,
 which may carry greater maternal or fetal risk. 
Second stage complications include a variety of complications related to the trauma of the delivery process
 to either the fetus or the mother. The fetus can suffer 1.acidemia 2.shoulder dystocia 3.bony fractures, 
nerve 4.palsies, scalp 5.hematomas and 6.anoxic brain injuries 

Similarly, the mother can develop a host of traumatic complications ranging from 1.uterine rupture,
 vaginal 2.laceration 3.cervical laceration 4.uterine hemorrhage 5.amniotic fluid embolism, and 6.death.
 The third stage of labor may encounter complications from hemorrhage, 1.cord avulsion 2.retained placenta,
 or 3.incomplete removal of the placenta.

Clinical Significance of the stages of labor

Defining the stages of labor with a specific beginning and end has allowed clinicians to study labor trends 
and to create labor curves. 
For example, in the 1950s, Dr. Friedman created a graphical representation of
 the rate of normal labor during latent and active labor using observed clinical data. These, in turn, can be 
used to determine if a woman is progressing through labor as expected and helping to identify abnormal
 labor. 
Friedman observed that labor typically has a sigmoidal shape when measured by cervical dilation
 over time. During the active phase of labor, cervical dilation occurs at a rate of 1 centimeter or more per
 hour.  If dilation occurs much slower, the patient may be at risk for abnormal labor or arrest of labor. 


If a woman is found not progressing through the first stage of labor as expected, this could lead to 
the diagnosis of the arrest of dilation or descent, which could result in cesarean delivery. 
The findings of Dr. Friedman have recently been challenged, and the current consensus is the normal
 latent phase of labor lasts longer than was previously observed.
 The criteria for the stages of labor create a universal language that allows healthcare professionals
 to communicate with one another about patient care accurately. 
Also, specific interventions are tailored to particular stages of labor to try to create better patient outcomes.
 For example, active management in the third stage of labor is carried out by placing immediate traction 
on the umbilical cord and administering intravenous oxytocin, which correlates with a lower risk of 
postpartum hemorrhage. Clinicians will continue to use the stages of labor to guide labor management and study labor patterns to improve patient care.

Quiz: Stages of Labor (Id:1760726)

https://www.statpearls.com/quiz/resume/1728250/

What is an ultrasound?

Ultrasound (also calledsonography or ultrasonography) 
is a noninvasive imaging test. 
An US picture is called a sonogram. 
Ultrasound uses high-frequency sound waves to create real-time pictures or video of internal
 organs or other soft tissues, such as blood vessels.
Ultrasound enables healthcare providers to “see” details of soft tissues inside your body without 
making any incisions (cuts). 
And unlike X-rays, ultrasound doesn’t use radiation.
Although most people associate ultrasound with pregnancy, healthcare providers use ultrasound
 for many different situations and to look at several different parts of the inside of your body.

How does an ultrasound work?

During an ultrasound, a healthcare provider passes a device called a transducer or probe over 
an area of your body or inside a body opening. 
The provider applies a thin layer of gel to your skin so that the ultrasound waves are transmitted 
from the transducer through the gel and into your body.
The probe converts electrical current into high-frequency sound waves and sends the waves into your body’s tissue. You can’t hear the sound waves.
Sound waves bounce off structures inside your body and back to the probe, which converts the waves
 into electrical signals. 
A computer then converts the pattern of electrical signals into real-time images or videos, which are displayed on a computer screen nearby.

What are the different kinds of ultrasounds? 

There are three main categories of ultrasound imaging, including:
    Pregnancy ultrasound (prenatal ultrasound).
    Diagnostic ultrasound.
    Ultrasound guidance for procedures.
Pregnancy ultrasound
Healthcare providers often use US (often called prenatal or obstetric US) to

 monitor you and the fetus during pregnancy.
Providers use prenatal US to:
    Confirm that you’re pregnant.
    Check to see if you’re pregnant with more than one fetus.
    Estimate how long you’ve been pregnant and the gestational age of the fetus.
    Check the fetal growth and position.
    See the fetal movement and heart rate.
    Check for congenital conditions (birth defects) in the fetal brain, spinal cord,

 heart or other parts of its body.
    Check the amount of amniotic fluid.
Most healthcare providers recommend an US at 20 weeks pregnant. This test

 tracks the fetus’s growth and development during pregnancy. This US may also 

show the biological sex of the fetus. Tell your technician if you do or do not want

 to know the sex.
Your provider may order extra scans to get answers to any questions or concerns,

 such as the potential for congenital conditions.
Diagnostic ultrasound
Providers use diagnostic US to view internal parts of your body to see if something

 is wrong or not working properly. They can help your provider learn more about

 what’s causing a wide range of symptoms, such as unexplained pain, masses (lumps) 

or what may be causing an abnormal blood test.
For most diagnostic US exams, the technician places the TXR on your skin. 

In some cases, they may need to place the probe inside your body, such as in

 your vagina or rectum.
The type of diagnostic ultrasound you have, depends on the details of your case.
Examples of diagnostic ultrasounds include:
 Abdominal US: An US probe moves across the skin of your midsection (belly) area. Abdominal ultrasound can diagnose many causes of abdominal pain.
  Kidney (renal) US: Providers use kidney ultrasound to assess the size, location and shape of your kidneys and related structures, such as your ureters and bladder.

 Ultrasound can detect cysts, tumors, obstructions or infections within or around your kidneys.
    Breast US: A breast US is a noninvasive test to identify breast lumps and cysts. 

Your provider may recommend an ultrasound after an abnormal mammogram.
    Doppler US: a special US technique that assesses the movement of materials,

 like blood, in your body. It allows your provider to see and evaluate blood flow

 through arteries and veins in your body. Doppler US is often used as part of a

 diagnostic ultrasound study or as part of a vascular ultrasound.
    Pelvic US: A pelvic US looks at the organs in your pelvic area between your lower abdomen (belly) and legs. Some of the pelvic organs include your bladder, prostate, rectum, ovaries, uterus and vagina.
    Transvaginal US: Your provider inserts a probe into your vaginal canal. 

It shows reproductive tissues such as your uterus or ovaries. 

A transvaginal US is sometimes called a pelvic US because it evaluates structures

 inside your pelvis (hip bones).
  Thyroid US: Providers use ultrasound to assess your thyroid, a butterfly-shaped endocrine gland in your neck. Thy can measure the size of your thyroid and see

 if there are nodules or lesions within the gland.
    Transrectal us: provider inserts an ultrasound transducer into your rectum.

 It evaluates your rectum or other nearby tissues, such as the prostate in people

 assigned male at birth.
Ultrasound guidance for procedures
Providers sometimes use US to perform certain procedures precisely. 

A common use of US is to guide needle placement to sample fluid or tissue from:
    Tendons.
    Joints.
    Muscles.
    Cysts or fluid collections.
    Soft-tissue masses.
    Organs (liver, kidney or prostate).
    Transplant organs (liver, kidney or pancreas).
Examples of other procedures that may require ultrasound guidance include:
    Embryo transfer for in vitro fertilization.
    Nerve blocks.
    Confirming the placement of an IUD (intrauterine device) after insertion.
    Lesion localization procedures.

What is the difference between a 3D ultrasound and a 4D ultrasound?

For US during pregnancy, the traditional US is a two-dimensional (2D) image of the fetus. 
2D US produces outlines and flat-looking images, which allows your health provider to see 
the fetus's internal organs and structures.
Three-dimensional (3D) US allows the visualization of some facial features of the fetus and

 possibly other body parts such as fingers and toes. 
Four-dimensional (4D) US is 3D ultrasound in motion. Providers rarely use 3D or 4D fetal US

imaging for medical purposes, though it can be useful in diagnosing a facial or skeletal issue.
 They do, however, use 3D US for other medical purposes, such as evaluating uterine polyps
 and fibroids.
While US is generally considered to be safe with very low risks, the risks may increase with
 unnecessary prolonged exposure to US energy or when untrained users operate an US machine.
 Because of this, the U.S. Food and Drug Administration (FDA) advises against getting a 3D US
 for non-medical reasons such as for “keepsake” moments or entertainment.

Who performs an ultrasound?

A doctor or a healthcare provider called an US technician or sonographer performs USs.
 They’re specially trained to operate an ultrasound machine properly and safely.
It’s important to always have your US performed by a medical professional and in a medical facility.

Test Details

How do I prepare for an ultrasound?

The preparations will depend on the type of US you’re having. Some types of ultrasounds
 require no preparation at all.
For US of the pelvis, including US during pregnancy, of the female reproductive system and of 
the urinary system, you may need to fill up your bladder by drinking water before the test.
For Abdominal US, you may need to adjust your diet or fast (not eat or drink anything except water)
 for several hours before your test.
In any case, your healthcare provider will let you know if you need to do anything special to prepare
 for your ultrasound. They may give you instructions during an appointment or when scheduling your ultrasound. 
Instructions may also be available in your electronic medical records if you use such a system.

What happens during an ultrasound?

Preparation for an US varies depending on what body part to be scanned. Your provider may
 ask you to remove certain pieces of clothes or change into a hospital gown.
Ultrasounds that involve applying the transducer (probe) over your skin (not in your body) 

follow these general steps:
  You’ll lie on your side or back on a comfortable table.
 The US technician will apply a small amount of water-soluble gel on your skin over the area
  to be examined. This gel doesn’t harm your skin or stain your clothes.
 The technician will move a handheld transducer over the gel to get images inside your body.
 The technician may ask you to be very still or to hold your breath for a few seconds to create
  clearer pictures.
 Once the technician has gotten enough images, they’ll wipe off any remaining gel on your skin
  and you’ll be done.
An US test usually takes 30 minutes to an hour. If you have any questions about your specific type of ultrasound, ask your healthcare provider.

Is an ultrasound painful?

USs that are performed externally (over your skin) are generally not painful. You won’t feel the 
sound waves that US uses. If asked to have a full bladder for the procedure, it may be 
uncomfortable.
 It may also be uncomfortable to lay on the exam table if you’re pregnant.
Ultrasounds that go inside body cavities, such as your vagina or rectum, may be uncomfortable,
 but they shouldn’t hurt.

Are ultrasounds safe?

Yes, research to date has largely shown US technology to be safe with no harmful side effects.
 US doesn’t use radiation, unlike some other medical imaging tests, such as X-rays and CT scans.
Still, all US should be done by a professional who has training in using this specialized 
technology safely.

Results and Follow-Up

When should I know the results of my ultrasound?

The time it takes to get your results depends on the type of ultrasound you get. In some cases,
 such as prenatal US, your provider may analyze the images and provide results during the test.
In other cases, a radiologist, a healthcare provider trained to supervise and interpret radiology 
exams, will analyze the images and then send the report to the provider who requested the exam.
 Your provider will then share the results with you or they may be available in your electronic medical record (if you have an account set up) before your provider reviews the results.

What conditions can be detected by ultrasound?

Ultrasound can help providers diagnose a wide range of medical issues, including:
Abnormal growths, such as tumors or cancer.
    Blood clots.
    Enlarged spleen.
    Ectopic pregnancy (when a fertilized egg implants outside of your uterus).
    Gallstones.
    Aortic aneurysm.
    Kidney or bladder stones.
    Cholecystitis (gallbladder inflammation).
    Varicocele (enlarged veins in the testicles).
What questions should I ask my healthcare provider about my ultrasound?
If you need an ultrasound, you may want to ask your provider the following questions:
    What type of ultrasound do I need?
    What should I do to prepare for my ultrasound?
    Do I need any other tests?
    When should I expect to get test results?
A note
Ultrasounds are common, safe and effective imaging tests. Make sure you get an ultrasound from a well-trained professional (sonographer) who understands how to use this technology properly. If you have any questions about your specific ultrasound test, talk to your healthcare provider. They’re available to help.
 https://my.clevelandclinic.org/health/diagnostics/4995-ultrasound

FAQs CONTD
How soon an US confirms pregnancy

Most practitioners wait until at least 6 weeks to perform the first pregnancy ultrasound. 
However, 1.a GS can be seen as early as 4 1/2 weeks after last period, & 2.a fetal heartbeat can be detected
 at 5 to 6 weeks (though that isn't always the case).
When to start showing pregnancy?

Typically, your bump becomes noticeable during the second trimester.
B/w 16-20 weeks, your body will start showing your baby's growth. For some women, their bump may
 not be noticeable until the end of the second trimester and even into the third trimester. 
The second trimester starts in the fourth month.

Is it safe to have a scan in early pregnancy?
There is no evidence that US scans can harm pregnancies. It is important to ensure, however,
 that the energy of US beam is kept As Low As Reasonably Achievable (ALARA "radiation principle").
 Use of pulsed Doppler (PWD) devices to measure blood flow should be avoided in the first weeks of pregnancy as their energy output is higher compared to the US beam used for standard imaging.
 Our equipment is fully compliant with the international standards for safe use in pregnancy and the machine energy output is continuously monitored during the examination.

Can you see Fallopian tubes on the scan?
Normal Fallopian tubes are very thin and they cannot be routinely seen on the scan. 
If the tubes are damaged, they tend to fill with fluid which makes it possible to see them. 
Tubal patency can be tested using a procedure called HyCoSy which is described in the section on the services we offer to women with concerns about their fertility.

Hysterocontrastsonography (HyCoSy Procedure)

A speculum is placed in the vagina (like having a smear test). 
A thin plastic catheter attached to a syringe is then passed through the neck of the (cervix). 
Water and dye is injected through the catheter. 
The flow of the water and dye is observed into the uterus and fallopian tubes with internal US.

What if I am allergic to Latex?
Allergy to Latex is rare, but it can sometimes cause severe anaphylactic reactions. 
If you think that you may be allergic to Latex please let us know so that we can avoid using 
gloves and probe covers which contain Latex during your examination.

Is there a risk of infection?
Our infection control policies are very stringent and we employ very elaborate procedures for 
cleaning of the US probes. Prior to and after each examination the probes are thoroughly cleansed

using antiseptic agents. 
The probes are then placed into a level disinfection device (Trophon) which is considered to be the
 best currently available method for cleaning US TXRs. 
Our doctors wear gloves during examinations and disposable probes covers are always used to
 provide additional protection from infection.





Can I have a scan if I am bleeding?
Vaginal bleeding does not affect quality of ultrasound diagnosis and scans can be safely 
performed during menstrual periods or on those with abortion or those who are experiencing 
irregular vaginal bleeding.

Are ultrasound scans painful?
Transvaginal US scans should not cause any significant discomfort and they are much easier to
 tolerate than smear tests. Transvaginal scans cannot be performed on unmarried women and in 
these women transabdominal scans are preferable.
 In menopausal pts with vaginal dryness, transvaginal examinations may be more uncomfortable.
 In order to minimise discomfort application of a lubrication gel containing local anaesthetic may 
make the examination easier to tolerate. Alternatively, local application of hormone oestrogen
 in the form of vaginal tablets or cream for one to two weeks prior to the examination 
may also be helpful.

Symptoms of early pregnancy
Significant hormonal changes take place during pregnancy. These

trigger a variety of symptoms.
 Some women experience many of the symptoms of pregnancy, while 
others may have only a few.
Symptoms of early pregnancy include :
 1.missed periods 
2.breast changes 
3.tiredness 
4.frequent urination
5.nausea and vomiting (morning sickness).
 However, these symptoms may be caused by other factors and 
do not necessarily mean that
 you are pregnant, so if you suspect you are pregnant take a home 
pregnancy test and see your GP.
A wide range of changes can occur in your body in the later stages
 of pregnancy, including :
 backache, headache, leg cramps or varicose veins, itch or tingling, 
constipation, haemorrhoids 
or indigestion, vaginitis or vaginal discharge, or mood changes or

depression. 
 See your GP right away if you experience symptoms like vaginal bleeding
 or breaking waters, chronic pain, high temperature, severe headaches or 
vision loss.
 Signs of Pregnancy
The signs of early pregnancy can include:
1.missed period
2. nausea and vomiting (often called ‘morning’ sickness, but it can occur
 at any time)
3. breast tenderness and enlargement
4. fatigue
5. passing urine more frequently than usual, particularly at night
6. cravings for some foods, distaste for foods you usually like, and 
a sour or metallic taste that persists
 even when you’re not eating (dysgeusia).
Many of pregnancy signs, such as a missed period (amenorrhoea),
 nausea (morning sickness) 
or tiredness can also be caused by stress or illness, so if you think you
 are pregnant take a home
 pregnancy test (urine test) or see your GP, who will administer a 
urine test, blood test or ultrasound scan.
Missed Period
Missing a period is often the first sign of possible pregnancy. 
However, some women experience light
 bleeding around the time of their expected period.

  Nausia & Vomiting  

‘Morning’ sickness is a condition that affects more than half of all 
pregnant women. 
The symptoms include nausea and vomiting, and loss of appetite. 
Many women with morning sickness don’t just get symptoms in the 
morning but experience them throughout the whole day.

Morning sickness usually begins around the fourth to sixth week of 
pregnancy and may settle 
by week 12, although it can continue for longer or return at 
around 32 weeks.

Breast changes

During pregnancy, the breasts become fuller, swollen and tender. 
These changes are similar to those you may have noticed in the few
 days before your period
 During pregnancy, the skin around the nipple becomes darker and the

veins in the breast become more obvious.

Fatigue

Overwhelming tiredness is common in early pregnancy. 1/This is most
 likely caused by the 1.massive 
increase in the sex hormone progesterone. Progesterone is A/needed
 to maintain the pregnancy 
and help the B/baby to grow, but it C/also slows your metabolism.
Try to get some more sleep or rest when you can during this early stage.
Your 2/energy levels will probably rise again by around the fourth month
of pregnancy when the placenta is well established.
Tiredness during pregnancy can also be 2.caused by anaemia, which 
is most commonly caused by iron deficiency. Eating iron-rich foods is
 important to prevent iron deficiency anaemia during pregnancy. 
Medical treatment of anaemia in pregnancy usually involves taking
 iron tablets & Sometimes an iron infusion is needed. 

This needs a hospital admission but only takes a few hours 

Some iron infusions can be given by your GP.

Frequent urination

Pregnancy causes 1.an increase in levels of body fluids and greater
 kidney efficiency. 
The increased uterus size, 2.also presses against the bladder. As a result

 most pts start experiencing more frequent urination within the first few

 weeks of becoming pregnant.

Food cravings

Cravings (intense desire & appetite) for certain foods are very common in pregnancy, especially 
for foods that provide energy and calcium, such as milk and other dairy products. 
You may also notice a sudden distaste for foods you previously liked.
Some women even develop an unusual taste for non-food items
 such as soil or paper. 
This is called ‘pica’ and may indicate a nutrient deficiency

 Please speak to your GP or midwife if this develops.
Other Symptoms of Pregnancy
Many of these symptoms may also be indicative of other conditions.
 If in doubt, see your GP.
    backache
    breathlessness
    constipation
    haemorrhoids (piles)
    headaches
    heartburn and indigestion
    itchy skin
    leg cramps
    mood changes (such as unexplained crying)
    tingling and numbness in your hands
    vaginal discharge
    vaginitis
    varicose veins and leg oedema (swelling)

Backache

Back pain during pregnancy can affect more than 1 in 3 women. 
This is usually due to loosening of ligaments and change in posture due to the growing baby.
You can help reduce back pain during pregnancy by wearing flat heeled shoes, using chairs 
with good back support, avoiding lifting heavy objects, and doing gentle exercise. 
Exercising in water can reduce back pain in pregnancy, and physiotherapy and acupuncture 
may also help.

Breathlessness

At the onset of pregnancy the hormone progesterone increases your lung capacity. 
This enables you to carry more oxygen to your baby and get rid of waste products such as
 the carbon dioxide that you both produce. 
At each breath you breathe more deeply and the amount of air you inhale (and exhale) 
increases significantly. This can make you feel short of breath.
In addition, as pregnancy approaches term, the pressure of the enlarging uterus and baby on
 your diaphragm can make your breathing feel more laboured.
Contact your doctor or midwife if you experience sudden onset of breathlessness associated 
with any of the following:
 pain
 palpitations (heart pounding)
 extreme tiredness
 exercise.

Constipation

Constipation refers to infrequent, hard bowel motions that are difficult to pass. 
Constipation is a common problem in pregnancy that is caused by pregnancy hormones
slowing your gastrointestinal movement, or by pressure of growing uterus on your rectum.
If you experience constipation during pregnancy, you are advised to:
drink plenty of water every day.
 increase your dietary fibre (such as bran, wheat and fresh fruit and vegetables).
 do gentle, low impact exercise such as swimming, walking or yoga.
Don't take over-the-counter laxatives without first consulting your midwife or GP. 
If changes to your diet and lifestyle don't make a difference, then your GP or midwife can
 prescribe a laxative that is safe to use in pregnancy.

Haemorrhoids (piles)

You may develop haemorrhoids (piles) as a result of straining from constipation or the pressure 
of your baby’s head. Be reassured, symptoms usually resolve on their own soon after birth.
 If you have bleeding from haemorrhoids, itching, discomfort or pain it is recommended that you :
1. Alleviate or prevent constipation by increasing your daily water and fibre intake 
 2. Sit in warm salty water for about 15 minutes, especially after a bowel motion 
 3.Apply haemorrhoid cream 
If the bleeding or pain continues, talk with your GP (doctor) or midwife.

Headaches

Contact your GP or midwife if you have a headache during pregnancy that is not relieved by 
paracetamol, such as Panadol, especially in the second half of pregnancy.
A persistent headache can be associated with pre-eclampsia – a condition that can 1.affect 
your kidneys and thus 2.increase blood pressure and 3.decrease blood flow to your baby.

Heartburn and indigestion

Heartburn, reflux or indigestion is pain and discomfort associated with acid from the stomach
 entering and ‘burning’ the oesophagus.
Indigestion is more common during pregnancy due to 1.the pressure of the enlarging uterus on 
the organs of the abdomen and 2.the action of progesterone that relaxes the muscle b/w the 
oesophagus and stomach(gastro-esophageal sphincter).
If you are experiencing heartburn, reflux or indigestion, it is recommended that you : 
Eat small and more frequent meals .1
2.Avoid eating just before going to bed
3. Sleep with extra pillows so your head is raised  
4. Wear loose-fitting clothing
5. Avoid any food or fluid that aggravates symptoms – such as fatty foods containing 
  ,fried foods, fatty meats and pastry, spicy foods including curry and chilli, alcohol & caffeine 
  including tea, coffee, chocolate and cola 
   Consult your doctor before taking antacids.
If these strategies do not relieve your symptoms, please consult your GP, who may prescribe 
a medication that will safely reduce the secretion of acid.

Itchy skin

Widespread itching over the body is not common in pregnancy but it can be very distressing, 
interfering with sleep and enjoyment of pregnancy. 
Dry skin and eczema are the most common causes but sometimes there may be no apparent
 cause for the itching. In rare cases, where the palms of the hands and soles of the feet are itchy, 
it may be due to serious liver disease – a blood test can be done to check for this.
An itchy rash later in pregnancy, is thought to be caused by the body’s reaction to the stretching
 of the skin. This is called PUPPS. Itching can be controlled using moisturisers and antihistamines.
 Ask your doctor or midwife what antihistamines are safe in pregnancy.

Leg cramps

Leg cramps occur due to a build-up of acids that cause involuntary contractions of the
 affected muscles. 
They are experienced by up to half of pregnant women, usually at night. 
Leg cramps are more likely in the second and third trimesters.
If you experience leg cramps, it is recommended that during an episode you:
Walk around .1
2. Stretch and massage the affected muscle(s) to disperse the build-up of acids.
3. Apply a warm pack to the affected muscle(s).

If you find cramps troublesome, discuss with your GP or midwife the option of taking magnesium
 lactate or citrate morning and evening.

Mood changes

Some newly pregnant women experience mood changes such as irritability. 
Other pregnant women experience feelings of elation. 
It is thought that the pregnancy hormones influence chemicals in the brain, causing mood changes.
During pregnancy, 1 in 10 women experience depression. 
Depression is treatable, so if you are feeling depressed or ‘down’ during pregnancy it is extremely
 important to get help early. 
Please contact your GP (doctor), midwife or maternal and child health nurse as soon as possible.

Tingling and numbness in your hands (carpal tunnel syndrome)

Carpal tunnel syndrome – tingling and numbness in your hands – affects up to 60 % of women
 during pregnancy. It is caused by compression of the median nerve due to an increase 
in the tissue fluids during pregnancy.
Carpal tunnel syndrome may be mild, intermittently painful, or severe, which may cause partial
 paralysis of the thumb or loss of sensation. 
Symptoms usually resolve on their own soon after birth.
If you are experiencing tingling and numbness in your hands, inform your doctor or midwife.
 In very severe cases, your doctor may recommend corticosteroid injections or surgical treatment.

Vaginal discharge

An increase in vaginal discharge is a common change during pregnancy. 
If it is associated with itchiness, pain, a bad odour or pain on passing urine then it may be due
 to an infection. Seek treatment from your GP.

Vaginitis

Vaginitis is inflammation of the vagina, and is a distressing complaint for many women. 
It is more frequent during pregnancy. 
Some causes of vaginitis include vaginal thrush, bacterial vaginosis, trichomoniasis and chlamydia.
 See your GP for diagnosis and treatment

Varicose veins and leg Oedema (swelling)

Varicose veins of the legs are very common in pregnancy due to a combination of factors,
 including 1.increased volume of circulating blood during pregnancy, and 2.pressure of the 
pregnant uterus on the larger veins. This 3.increased pressure on the veins can also result 
in swelling of the legs (oedema) that can cause : *pain *feelings of heaviness *cramps
  especially at night *and other unusual sensations.
If you have varicose veins, it is recommended thWear support stockings.
 1. Avoid standing for long periods.
2. Exercise gently and regularly (walking or swimming).
3. Lie down to rest with feet elevated, when you can.
4. Try massaging your legs.
    Tell your doctor or midwife at your next pregnancy visit