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Question 1General Sonography and Maternal Fetal Health

On a transabdominal pelvic sonogram, which structure is typically identified as a landmark for locating the ovaries?

  1. Rectum
  2. Internal iliac vein Correct answer.
  3. External iliac artery
  4. Femoral artery

Explanation

The ovaries are usually found medial to the internal iliac vein, which serves as a reliable landmark during transabdominal scanning. The external iliac vessels lie more lateral and anterior and are not used as the primary ovarian landmark.

Question 2General Sonography and Maternal Fetal Health

Which measurement plane is used to obtain the biparietal diameter (BPD) in a fetal head?

  1. Axial plane at the level of the thalami Correct answer.
  2. Oblique plane through the cerebellum
  3. Sagittal plane through the midline
  4. Coronal plane through the orbits

Explanation

The BPD is measured in an axial plane at the level of the thalami, with the falx cerebri continuous and the cavum septi pellucidi visible anteriorly. This plane ensures consistent caliper placement on the outer-to-outer skull margins.

Question 3General Sonography and Maternal Fetal Health

A first-trimester ultrasound shows a gestational sac with a mean sac diameter of 25 mm and no visible embryo. According to standard criteria, this finding is most consistent with which diagnosis?

  1. Incomplete miscarriage
  2. Anembryonic pregnancy Correct answer.
  3. Normal early pregnancy
  4. Ectopic pregnancy

Explanation

A mean sac diameter of 25 mm or greater without an embryo is one accepted criterion for an anembryonic pregnancy (blighted ovum). This threshold indicates the pregnancy has failed to develop an embryo and warrants follow-up or confirmation per institutional protocol.

Question 4General Sonography and Maternal Fetal Health

Which Doppler waveform pattern is characteristic of a normal umbilical artery in a healthy third-trimester pregnancy?

  1. Forward end-diastolic flow Correct answer.
  2. Reversed end-diastolic flow
  3. Absent end-diastolic flow
  4. Biphasic systolic reversal

Explanation

A normal umbilical artery waveform demonstrates continuous forward flow throughout diastole, reflecting low placental vascular resistance. Absent or reversed diastolic flow indicates increased resistance and placental insufficiency.

Question 5General Sonography and Maternal Fetal Health

When performing a transvaginal ultrasound to evaluate the uterus, which probe orientation places the transducer face against the anterior fornix?

  1. Coronal with the marker to the patient's right
  2. Transverse with the marker to the patient's left
  3. Sagittal with the marker toward the ceiling
  4. Sagittal with the marker toward the floor Correct answer.

Explanation

For transvaginal imaging, the probe is inserted with the marker oriented toward the floor (anterior) so the image display shows the bladder anteriorly and the rectum posteriorly. This orientation produces a standard sagittal midline view of the uterus.

Question 6General Sonography and Maternal Fetal Health

Which sonographic finding is most suggestive of a complete hydatidiform mole?

  1. Thickened fetal nuchal translucency
  2. Snowstorm appearance with cystic spaces Correct answer.
  3. Single gestational sac with yolk sac
  4. Multiple gestational sacs

Explanation

A complete mole typically presents as an enlarged uterus filled with a heterogeneous echogenic mass containing numerous small cystic spaces, often described as a snowstorm appearance. No fetal parts are present in a complete mole.

Question 7General Sonography and Maternal Fetal Health

A patient at 20 weeks presents with painless vaginal bleeding. Ultrasound reveals the placental edge covering the internal cervical os. This finding is best described as which condition?

  1. Vasa previa
  2. Placenta accreta
  3. Placental abruption
  4. Placenta previa Correct answer.

Explanation

Placenta previa is defined by placental tissue covering or reaching the internal cervical os, and it classically causes painless vaginal bleeding in the second or third trimester. Abruption typically presents with painful bleeding and a retroplacental clot.

Question 8General Sonography and Maternal Fetal Health

Which parameter is measured to assess fetal growth in the abdominal circumference plane?

  1. Nuchal fold thickness
  2. Transverse abdominal diameter at the stomach level Correct answer.
  3. Crown-rump length
  4. Cisterna magna depth

Explanation

The abdominal circumference is obtained in a transverse plane at the level of the fetal stomach and umbilical vein, measuring the outer skin line. This measurement reflects fetal nutritional status and hepatic size.

Question 9General Sonography and Maternal Fetal Health

During a transabdominal scan, a cystic structure is seen within the fetal brain at the level of the thalami, midline, and anterior. This structure is most likely which of the following?

  1. Cavum septi pellucidi Correct answer.
  2. Fourth ventricle
  3. Cisterna magna
  4. Choroid plexus cyst

Explanation

The cavum septi pellucidi is a normal midline fluid space between the frontal horns, located anteriorly at the level of the thalami. Its presence confirms the correct plane for BPD measurement.

Question 10General Sonography and Maternal Fetal Health

Which of the following best describes the appearance of a normal corpus luteum on ultrasound?

  1. Complex cyst with internal echoes and peripheral vascularity Correct answer.
  2. Solid hypoechoic mass with shadowing
  3. Anechoic simple cyst with thin wall
  4. Multiple tiny cysts arranged peripherally

Explanation

A corpus luteum often appears as a complex cyst with internal echoes, thickened walls, and peripheral vascularity (ring of fire) on Doppler. This reflects its role in progesterone production after ovulation.

Question 11General Sonography and Maternal Fetal Health

A patient presents with a positive pregnancy test and pelvic pain. Transvaginal ultrasound shows an empty uterus with a complex adnexal mass and free fluid. Which diagnosis should be highest on the differential?

  1. Complete mole
  2. Ectopic pregnancy Correct answer.
  3. Normal intrauterine pregnancy
  4. Threatened miscarriage

Explanation

An empty uterus with a complex adnexal mass and free fluid in a patient with a positive pregnancy test is highly suspicious for an ectopic pregnancy. This is a medical emergency requiring prompt evaluation and management.

Question 12General Sonography and Maternal Fetal Health

Which of the following is the correct method for measuring crown-rump length (CRL) in a first-trimester fetus?

  1. From the yolk sac to the fetal pole in a transverse view
  2. From the top of the head to the bottom of the feet in a sagittal view
  3. From the biparietal diameter to the sacrum in a coronal view
  4. From the outer skull to the rump in a midsagittal view Correct answer.

Explanation

CRL is measured in a true midsagittal plane from the outer margin of the fetal skull to the caudal end (rump), with the fetus in a neutral position. This measurement is most accurate between 7 and 13 weeks.

Question 13General Sonography and Maternal Fetal Health

Which finding on a fetal anatomic survey is most associated with an increased risk of Down syndrome?

  1. Echogenic intracardiac focus
  2. Mild pyelectasis
  3. Increased nuchal translucency Correct answer.
  4. Choroid plexus cyst

Explanation

Increased nuchal translucency is one of the strongest sonographic markers for Down syndrome and other aneuploidies. The other listed findings are soft markers with lower individual association.

Question 14General Sonography and Maternal Fetal Health

What is the primary purpose of performing a nuchal translucency measurement?

  1. To evaluate placental maturity
  2. To screen for aneuploidy and structural anomalies Correct answer.
  3. To assess fetal cardiac function
  4. To measure amniotic fluid volume

Explanation

Nuchal translucency measurement between 11 and 14 weeks is used to screen for chromosomal abnormalities such as trisomy 21 and certain structural anomalies. An enlarged NT increases the risk of aneuploidy and cardiac defects.

Question 15General Sonography and Maternal Fetal Health

A 32-week fetus demonstrates an amniotic fluid index of 26 cm. This finding is best classified as which of the following?

  1. Normal amniotic fluid volume
  2. Oligohydramnios
  3. Polyhydramnios Correct answer.
  4. Borderline low fluid

Explanation

An amniotic fluid index greater than 24 cm is classified as polyhydramnios. This may be associated with maternal diabetes, fetal anomalies, or multifetal gestation.

Question 16General Sonography and Maternal Fetal Health

Which Doppler parameter is most useful in evaluating fetal anemia?

  1. Umbilical artery pulsatility index
  2. Middle cerebral artery peak systolic velocity Correct answer.
  3. Ductus venosus a-wave
  4. Uterine artery resistance index

Explanation

Middle cerebral artery peak systolic velocity is the standard noninvasive method for detecting fetal anemia, as increased velocity reflects reduced blood viscosity. Values above 1.5 multiples of the median suggest significant anemia.

Question 17General Sonography and Maternal Fetal Health

Which of the following best describes the sonographic appearance of a subchorionic hemorrhage?

  1. Anechoic collection between the gestational sac and uterine wall Correct answer.
  2. Thickened placental tissue with cystic spaces
  3. Echogenic mass within the fetal brain
  4. Fluid collection within the fetal abdomen

Explanation

A subchorionic hemorrhage appears as an anechoic or hypoechoic crescent-shaped collection between the gestational sac and the uterine wall. Its size and location influence the risk of pregnancy loss.

Question 18General Sonography and Maternal Fetal Health

A patient with a history of infertility presents with an adnexal mass showing a 'spoke-wheel' appearance on color Doppler. This finding is most consistent with which condition?

  1. Ovarian hyperstimulation
  2. Ectopic pregnancy
  3. Corpus luteum cyst
  4. Ovarian torsion Correct answer.

Explanation

A spoke-wheel pattern of vascularity in an enlarged ovary with peripheral follicles is characteristic of ovarian torsion, reflecting twisted vascular pedicle. Prompt surgical intervention is required to preserve ovarian function.

Question 19General Sonography and Maternal Fetal Health

Which measurement is used to determine gestational age most accurately in the second trimester?

  1. Head circumference Correct answer.
  2. Abdominal circumference
  3. Biparietal diameter
  4. Femur length

Explanation

Head circumference is considered the most reliable single measurement for estimating gestational age in the second trimester when dating by last menstrual period is uncertain. It is less affected by fetal position and growth variation than other parameters.

Question 20General Sonography and Maternal Fetal Health

Which sonographic sign is most characteristic of a fetal neural tube defect such as spina bifida?

  1. Double bubble sign
  2. Ring of fire
  3. Snowstorm appearance
  4. Lemon sign and banana sign Correct answer.

Explanation

The lemon sign (scalloped frontal bones) and banana sign (curved cerebellum) are classic cranial signs associated with open spina bifida. These result from altered cerebrospinal fluid dynamics and Chiari II malformation.

Question 21General Sonography and Maternal Fetal Health

During a transabdominal scan, which structure is typically visualized anterior to the uterus in a non-pregnant patient?

  1. Urinary bladder Correct answer.
  2. Rectum
  3. Cul-de-sac
  4. Sacrum

Explanation

The urinary bladder lies anterior to the uterus and serves as an acoustic window for transabdominal pelvic imaging when adequately filled. The rectum and cul-de-sac are located posteriorly.

Question 22General Sonography and Maternal Fetal Health

A fetal heart is evaluated at 22 weeks. Which view is best for assessing the four-chamber view?

  1. Short-axis view at the great vessels
  2. Coronal view of the ductus arteriosus
  3. Apical four-chamber view Correct answer.
  4. Sagittal view of the aortic arch

Explanation

The apical four-chamber view allows simultaneous visualization of both atria and ventricles, the interventricular septum, and the atrioventricular valves. It is the standard screening view for congenital heart defects.

Question 23General Sonography and Maternal Fetal Health

Which of the following findings on a pelvic ultrasound is most consistent with adenomyosis?

  1. Anechoic simple cyst in the ovary
  2. Thin uniform endometrium
  3. Asymmetric myometrial thickening with cystic spaces Correct answer.
  4. Hyperechoic mass within the endometrial cavity

Explanation

Adenomyosis presents with asymmetric myometrial thickening, heterogeneous echotexture, and small myometrial cysts, often with a thickened junctional zone. These reflect endometrial tissue within the myometrium.

Question 24General Sonography and Maternal Fetal Health

What is the recommended fetal position for measuring nuchal translucency?

  1. Neutral head position with the fetus in a midsagittal plane Correct answer.
  2. Any position with the fetus floating in amniotic fluid
  3. Flexed neck in a transverse plane
  4. Hyperextended neck in a coronal plane

Explanation

NT should be measured in a true midsagittal plane with the fetal head in a neutral position, avoiding hyperextension or flexion, which can falsely increase or decrease the measurement. The fetus should occupy most of the image.

Question 25General Sonography and Maternal Fetal Health

Which of the following best explains why Doppler ultrasound should be used cautiously in the first trimester?

  1. Increased risk of thermal injury to the developing embryo Correct answer.
  2. Doppler requires contrast agents
  3. Doppler causes fetal heart rate abnormalities
  4. Doppler cannot detect flow in early pregnancy

Explanation

Doppler ultrasound uses higher energy levels than B-mode, increasing the potential for thermal bioeffects in the developing embryo. The ALARA principle should be applied, and Doppler should be reserved for clear clinical indications.

Question 26General Sonography and Maternal Fetal Health

On a transvaginal scan, which measurement plane is used to obtain a reliable nuchal translucency thickness?

  1. A mid-sagittal view of the fetal face with the neck in neutral position Correct answer.
  2. An oblique view through the fetal skull showing the lateral ventricles
  3. A coronal view through the fetal abdomen showing the stomach bubble
  4. A transverse view through the fetal thorax at the level of the heart

Explanation

Nuchal translucency is measured on a true mid-sagittal section of the fetus with the head in a neutral position so the translucent space behind the neck is seen clearly. The calipers are placed on the inner borders of the nuchal space at its widest point. Transverse and coronal planes do not display the nuchal region correctly.

Question 27General Sonography and Maternal Fetal Health

Which structure is identified as the fetal stomach in a normal second-trimester abdominal survey?

  1. A cystic structure in the midline of the posterior fossa
  2. An echogenic focus within the right renal pelvis
  3. An anechoic area in the left upper abdomen at the level of the four-chamber heart Correct answer.
  4. A fluid-filled tubular structure anterior to the spine in the pelvis

Explanation

The fetal stomach appears as an anechoic fluid-filled structure in the left upper abdomen, typically seen in the same axial plane as the four-chamber heart. Its position on the left side helps confirm normal situs. Absence or right-sided position raises concern for esophageal atresia or situs abnormalities.

Question 28General Sonography and Maternal Fetal Health

A first-trimester transvaginal scan shows a gestational sac with a mean sac diameter of 20 mm and no visible yolk sac or embryo. What is the most appropriate interpretation?

  1. Findings represent a pseudogestational sac associated with ectopic pregnancy
  2. Findings indicate a normal pregnancy at approximately 5 weeks of gestation
  3. Findings are consistent with an early pregnancy that requires follow-up in one week
  4. Findings meet criteria for pregnancy failure and should prompt discussion of management Correct answer.

Explanation

A mean sac diameter of 20 mm or greater without a visible yolk sac or embryo is a recognized criterion for pregnancy failure. At this size, embryonic structures should be identifiable on transvaginal scanning. Follow-up scanning is not required when this threshold is met.

Question 29General Sonography and Maternal Fetal Health

Which sonographic feature best distinguishes a mature cystic teratoma from a simple ovarian cyst?

  1. A multilocular cyst with thin internal septations
  2. A uniformly hypoechoic solid mass with posterior enhancement
  3. A unilocular anechoic cyst with a thin smooth wall
  4. A hyperechoic mural nodule with acoustic shadowing Correct answer.

Explanation

A mature cystic teratoma often contains a Rokitansky nodule, an echogenic mural component that may shadow due to fat, hair, or calcification. Simple cysts are anechoic with thin walls and no solid components. The presence of a shadowing echogenic nodule is a key distinguishing feature.

Question 30General Sonography and Maternal Fetal Health

During a transabdominal pelvic scan, the bladder is used primarily for which purpose?

  1. To evaluate the anterior abdominal wall musculature
  2. To act as an acoustic window for visualizing the uterus and ovaries Correct answer.
  3. To assess ureteral peristalsis in real time
  4. To measure residual urine volume after voiding

Explanation

A moderately full bladder displaces bowel loops and provides a fluid-filled acoustic window that improves transmission of sound to the uterus and adnexa. This is why patients are asked to fill their bladder before transabdominal pelvic scanning. An overly distended bladder can distort anatomy, so moderate filling is preferred.

Question 31General Sonography and Maternal Fetal Health

A 28-week fetus has an estimated fetal weight below the 10th percentile with a normal umbilical artery Doppler. Which additional parameter best helps distinguish constitutionally small from growth-restricted fetuses?

  1. Maternal body mass index
  2. Amniotic fluid index
  3. Cerebroplacental ratio Correct answer.
  4. Fetal lie on physical examination

Explanation

The cerebroplacental ratio reflects redistribution of fetal blood flow and is often reduced in true growth restriction even when the umbilical artery Doppler is normal. A normal ratio supports a constitutionally small fetus. Amniotic fluid and maternal factors are less specific for this distinction.

Question 32General Sonography and Maternal Fetal Health

Which finding on a first-trimester ultrasound is most consistent with a normal intrauterine pregnancy at approximately 7 weeks?

  1. An empty uterus with a complex adnexal mass
  2. A snowstorm appearance of the uterine cavity
  3. A gestational sac containing a yolk sac and a fetal pole with cardiac activity Correct answer.
  4. A gestational sac with a mean diameter of 30 mm and no embryo

Explanation

By about 7 weeks, a yolk sac and fetal pole with detectable cardiac activity should be visible within the gestational sac. This confirms a viable intrauterine pregnancy and allows dating by crown-rump length. Absence of these structures at this stage warrants concern.

Question 33General Sonography and Maternal Fetal Health

Which Doppler waveform pattern in the umbilical artery is most concerning for worsening placental insufficiency?

  1. Pulsatility index within the normal reference range
  2. Absent end-diastolic flow Correct answer.
  3. Low-resistance forward flow throughout diastole
  4. High-resistance flow with a small diastolic component

Explanation

Absent end-diastolic flow in the umbilical artery indicates increased placental vascular resistance and is a sign of significant placental insufficiency. It is associated with adverse perinatal outcomes and often prompts intensified surveillance or delivery planning. Normal pregnancies show continuous forward diastolic flow.

Question 34General Sonography and Maternal Fetal Health

A patient at 18 weeks has a cervical length of 22 mm on transvaginal ultrasound. What is the clinical significance of this measurement?

  1. It indicates a short cervix and increased risk of preterm birth Correct answer.
  2. It is an artifact caused by bladder filling
  3. It is within normal limits for gestational age
  4. It suggests cervical insufficiency requiring immediate cerclage in all cases

Explanation

A transvaginal cervical length of 25 mm or less in the mid-trimester is considered short and is associated with an increased risk of spontaneous preterm birth. Management may include progesterone or cerclage depending on history and findings. A length of 22 mm is below the threshold and warrants attention.

Question 35General Sonography and Maternal Fetal Health

Which sonographic appearance is characteristic of a normal fetal bladder in the second trimester?

  1. A hyperechoic mass in the midline of the upper abdomen
  2. A cystic structure within the fetal chest adjacent to the heart
  3. A fluid collection surrounding the fetal liver
  4. An anechoic round structure in the lower pelvis between the umbilical arteries Correct answer.

Explanation

The fetal bladder appears as an anechoic, round structure in the pelvis, situated between the two umbilical arteries on color Doppler. Identifying it confirms urine production and helps assess the urinary tract. Its absence may raise concern for renal agenesis or bladder outlet obstruction.

Question 36General Sonography and Maternal Fetal Health

Which finding on a fetal echocardiogram most suggests a ventricular septal defect?

  1. A normal offset of the atrioventricular valves
  2. A pericardial effusion surrounding the heart
  3. A dropout in the interventricular septum seen on the four-chamber view with color flow across it Correct answer.
  4. An echogenic focus in the left ventricle without flow disturbance

Explanation

A ventricular septal defect appears as a discontinuity in the interventricular septum, often confirmed by color Doppler showing flow across the defect. The four-chamber view is a standard screening plane for this finding. Small defects may be missed without color flow.

Question 37General Sonography and Maternal Fetal Health

What is the primary sonographic sign of a placenta accreta spectrum disorder?

  1. Loss of the normal retroplacental clear zone with irregular placental lacunae Correct answer.
  2. A homogeneous placenta with a smooth maternal surface
  3. A thin placenta with a single cotyledon
  4. Placental thickness less than 2 cm at term

Explanation

Placenta accreta spectrum is suggested by loss of the retroplacental clear zone, multiple irregular placental lacunae, and disrupted bladder wall interface. These features reflect abnormal trophoblastic invasion of the myometrium. Color Doppler may show chaotic vascularity.

Question 38General Sonography and Maternal Fetal Health

Which measurement is most useful for estimating gestational age in a fetus with an enlarged nuchal translucency at 12 weeks?

  1. Crown-rump length Correct answer.
  2. Femur length
  3. Biparietal diameter
  4. Abdominal circumference

Explanation

Crown-rump length remains the most accurate parameter for dating in the first trimester, even when nuchal translucency is enlarged. Nuchal translucency assessment itself is interpreted relative to crown-rump length. Second- and third-trimester parameters are less precise for dating.

Question 39General Sonography and Maternal Fetal Health

On a transvaginal scan, which finding is most consistent with a normal ovary in a reproductive-age woman?

  1. A solid hypoechoic mass with internal vascularity
  2. A hyperechoic mass with posterior acoustic shadowing
  3. A unilocular cyst larger than 10 cm
  4. An oval structure containing multiple small anechoic follicles Correct answer.

Explanation

A normal reproductive-age ovary typically appears as an oval structure with multiple small anechoic follicles arranged peripherally or throughout the stroma. Follicle number and size vary with the menstrual cycle. Solid or very large cystic lesions warrant further evaluation.

Question 40General Sonography and Maternal Fetal Health

A 24-week fetus shows ventriculomegaly with an atrial width of 14 mm. Which additional finding is most important to assess for underlying causes?

  1. Corpus callosum and posterior fossa anatomy Correct answer.
  2. Fetal foot length
  3. Maternal serum alpha-fetoprotein only
  4. Placental grade

Explanation

When ventriculomegaly is identified, detailed assessment of the corpus callosum, posterior fossa, and cortical development helps identify associated central nervous system anomalies. These findings influence prognosis and counseling. Isolated mild ventriculomegaly may be benign, but associated anomalies change management.

Question 41General Sonography and Maternal Fetal Health

Which finding is most characteristic of an anembryonic pregnancy on transvaginal ultrasound?

  1. A gestational sac containing a yolk sac but no embryo at 8 weeks
  2. An echogenic mass within the uterine cavity with cystic spaces
  3. A gestational sac with a mean diameter of 25 mm and no yolk sac or embryo Correct answer.
  4. A gestational sac with a fetal pole measuring 7 mm and no cardiac activity

Explanation

An anembryonic pregnancy is diagnosed when the gestational sac exceeds size criteria without any visible yolk sac or embryo. A mean sac diameter of 25 mm or more without embryonic structures meets this criterion. Earlier scans may require follow-up before diagnosis.

Question 42General Sonography and Maternal Fetal Health

Which sonographic sign is most suggestive of a fetal abdominal wall defect involving herniation of bowel?

  1. A fluid collection in the fetal pleural space
  2. A cystic structure in the fetal pelvis
  3. An echogenic mass in the left upper abdomen
  4. A midline anterior abdominal wall defect with free-floating bowel in amniotic fluid Correct answer.

Explanation

Gastroschisis appears as a full-thickness anterior abdominal wall defect, usually to the right of the umbilicus, with bowel loops floating freely in amniotic fluid. Omphalocele, by contrast, is covered by a membrane and involves the umbilical cord insertion. Distinguishing the two guides counseling.

Question 43General Sonography and Maternal Fetal Health

What is the effect of maternal obesity on transabdominal obstetric ultrasound image quality?

  1. It decreases penetration and may require adjustment of frequency and depth Correct answer.
  2. It improves resolution by increasing the acoustic window
  3. It eliminates the need for transvaginal scanning
  4. It has no effect on image quality

Explanation

Increased maternal adipose tissue attenuates sound and reduces image resolution, particularly at higher frequencies. Sonographers may need to lower transducer frequency, increase depth, and optimize settings to improve visualization. Transvaginal scanning can be valuable when transabdominal images are limited.

Question 44General Sonography and Maternal Fetal Health

Which parameter is used to classify oligohydramnios using the amniotic fluid index?

  1. An amniotic fluid index of 5 cm or less Correct answer.
  2. An amniotic fluid index between 5 and 24 cm
  3. An amniotic fluid index greater than 24 cm
  4. A single deepest pocket greater than 8 cm

Explanation

Oligohydramnios is generally defined as an amniotic fluid index of 5 cm or less, or a single deepest pocket under 2 cm. These thresholds help identify fetuses at risk for umbilical cord compression and pulmonary hypoplasia. Normal AFI ranges are typically 5 to 24 cm.

Question 45General Sonography and Maternal Fetal Health

A patient presents with pelvic pain and a positive pregnancy test. Transvaginal ultrasound shows an empty uterus and a complex adnexal mass. Which next step is most appropriate?

  1. Reassure the patient and schedule a scan in four weeks
  2. Proceed directly to surgery without further testing
  3. Perform a hysterosalpingogram immediately
  4. Evaluate for ectopic pregnancy and correlate with serial beta-hCG levels Correct answer.

Explanation

An empty uterus with a complex adnexal mass in a patient with a positive pregnancy test raises high suspicion for ectopic pregnancy. Serial beta-hCG measurements and close follow-up help confirm the diagnosis and guide management. Immediate surgery is reserved for hemodynamically unstable patients.

Question 46General Sonography and Maternal Fetal Health

Which finding is most consistent with a subchorionic hematoma on ultrasound?

  1. A crescent-shaped anechoic or hypoechoic collection between the chorion and uterine wall Correct answer.
  2. A thin echogenic line separating the endometrial layers
  3. A complex cystic mass in the adnexa
  4. A uniformly echogenic mass within the endometrial cavity

Explanation

A subchorionic hematoma appears as a crescentic fluid collection between the gestational sac and the uterine wall. Its echogenicity varies with the age of the bleed. It is a common cause of first-trimester vaginal bleeding.

Question 47General Sonography and Maternal Fetal Health

Which sonographic finding is most suggestive of a fetal neural tube defect on a second-trimester scan?

  1. A normal cisterna magna measuring 4 mm
  2. A single umbilical artery
  3. A lemon-shaped skull with a banana-shaped cerebellum Correct answer.
  4. An echogenic intracardiac focus

Explanation

The lemon sign, a scalloped frontal bone contour, and the banana sign, an abnormally curved cerebellum, are classic intracranial signs of spina bifida. These findings result from altered cerebrospinal fluid dynamics and associated Chiari malformation. Direct spinal imaging confirms the defect.

Question 48General Sonography and Maternal Fetal Health

Which factor most limits the accuracy of fetal weight estimation by ultrasound in the third trimester?

  1. Measurement of the biparietal diameter in an axial plane
  2. Adequate amniotic fluid volume
  3. Use of the Hadlock formula with multiple biometric parameters
  4. Wide biological variability in fetal body composition near term Correct answer.

Explanation

Third-trimester estimated fetal weight is limited by biological variation in fetal fat and lean mass, which formulas cannot capture precisely. Accuracy is typically within 10 to 15 percent of actual birth weight. Technical factors also contribute but biological variability is a major source of error.

Question 49General Sonography and Maternal Fetal Health

Which structure is typically visualized in the posterior fossa on a normal fetal neurosonogram?

  1. An absent cerebellar vermis
  2. A dilated fourth ventricle with a keyhole shape
  3. A fluid-filled space measuring greater than 15 mm
  4. Cisterna magna measuring 2 to 10 mm Correct answer.

Explanation

A normal cisterna magna measures approximately 2 to 10 mm in the second and third trimesters. Enlargement may suggest a posterior fossa anomaly such as Dandy-Walker malformation. The cerebellar vermis should be intact and the fourth ventricle normal in size.

Question 50General Sonography and Maternal Fetal Health

Which technique best improves visualization of the fetal heart during a transabdominal scan in a fetus with an unfavorable position?

  1. Applying prolonged high-pressure pressure over the fundus
  2. Increasing the depth and using a lower-frequency transducer Correct answer.
  3. Performing the exam only in the first trimester
  4. Switching to a linear high-frequency probe

Explanation

When fetal position or maternal habitus limits cardiac visualization, lowering the transducer frequency and adjusting depth can improve penetration. Having the patient change position or waiting for fetal movement may also help. High-frequency linear probes are not suitable for deep transabdominal fetal imaging.