OB/GYN Ultrasound Board Exam Review
2026/2027: 50 High-Yield Questions with
Answers & Explanations | Fetal Anomalies,
Doppler, First-Trimester Screening &
Maternal-Fetal Medicine
Description:
Master the 2026/2027 Obstetrics and Gynecology Ultrasound board exam with this
comprehensive test bank featuring 50 expertly crafted multiple-choice questions covering fetal
anomalies, chromosomal abnormalities, twin pregnancy complications, Doppler
hemodynamics, first-trimester screening, placental pathology, and maternal-fetal medicine.
Each question includes detailed evidence-based explanations aligned with ISUOG, AIUM, and
ACOG guidelines. Updated for 2026/2027 academic standards, this resource is ideal for
medical students, residents, sonography trainees, and exam candidates preparing for board
certification.
Download now to maximize your exam readiness and achieve success in your OB/GYN ultrasound
rotation and certification examinations!
, OB/GYN Ultrasound Exam Prep 2026/2027
SECTION A: FIRST TRIMESTER ULTRASOUND AND GENETIC TESTING
Question 1
Which chromosomal abnormality demonstrates the strongest association with cystic hygromas
on prenatal ultrasound?
A. Trisomy 18
B. Trisomy 13
C. Turner syndrome (45,X)
D. Triploidy
Answer: C. Turner syndrome (45,X)
Explanation: Turner syndrome is the most frequently identified chromosomal abnormality
associated with cystic hygromas, which represent lymphatic malformations typically located in
the nuchal region. Approximately 75% of fetuses with Turner syndrome demonstrate cystic
hygromas on first-trimester ultrasound, making this finding a key diagnostic indicator. While
cystic hygromas may occasionally be observed in other aneuploidies including Trisomy 21,
Trisomy 18, and Trisomy 13, their prevalence in Turner syndrome is significantly higher and
clinically more specific.
Question 2
At which gestational age range is chorionic villus sampling (CVS) most appropriately performed
for routine prenatal genetic diagnosis?
A. 7-8 weeks
B. 10-13 weeks
C. 15-17 weeks
D. 19-22 weeks
Answer: B. 10-13 weeks
,Explanation: The optimal window for chorionic villus sampling is between 10 and 13 weeks of
gestation. This timeframe allows for adequate placental tissue development while minimizing
procedural risks. Early CVS (before 10 weeks) is associated with increased rates of fetal loss and
limb reduction defects, whereas CVS after 13 weeks poses greater technical challenges and may
be superseded by amniocentesis. Current 2026/2027 clinical guidelines recommend CVS
between 11 and 13+6 weeks, coinciding with the nuchal translucency screening window.
Question 3
A patient presents with vaginal bleeding and a serum beta-human chorionic gonadotropin level
of 35,000 mIU/mL. Transvaginal ultrasound reveals an empty uterine cavity and a complex
adnexal mass. Which diagnosis is most likely?
A. Molar pregnancy
B. Blighted ovum
C. Ectopic pregnancy
D. Missed abortion
Answer: C. Ectopic pregnancy
Explanation: The combination of elevated beta-hCG (35,000 mIU/mL), vaginal bleeding, an
empty uterus, and an adnexal mass is highly suggestive of an ectopic pregnancy. While beta-
hCG levels in ectopic pregnancies typically rise more slowly and plateau at lower levels than
normal intrauterine pregnancies, levels exceeding 30,000 mIU/mL can occur, particularly in
tubal ectopic pregnancies. The presence of an adnexal mass corresponding to the side of pain or
bleeding further supports this diagnosis. Molar pregnancies would demonstrate a characteristic
"snowstorm" appearance within the uterus, while blighted ovum and missed abortion would
show intrauterine findings.
Question 4
Which nuchal translucency measurement finding is most consistently associated with
chromosomally abnormal fetuses?
A. Normal measurement (<3.0 mm)
B. Increased measurement (≥3.5 mm)
, C. Absent nuchal translucency
D. Decreased measurement (<1.0 mm)
Answer: B. Increased measurement (≥3.5 mm)
Explanation: Increased nuchal translucency (NT) measurement, typically defined as ≥3.5 mm or
above the 95th percentile for gestational age, demonstrates a strong correlation with
chromosomal abnormalities, particularly Trisomy 21, Trisomy 18, and Turner syndrome. The
pathophysiological mechanism involves abnormal lymphatic drainage and increased interstitial
fluid accumulation. Current 2026/2027 guidelines recommend combined first-trimester screening
incorporating NT measurement, maternal serum biomarkers (PAPP-A and free β-hCG), maternal
age, and additional ultrasound markers to achieve detection rates exceeding 90% for Trisomy 21.
SECTION B: FETAL ANATOMY AND CENTRAL NERVOUS SYSTEM
Question 5
Which abnormality is most commonly associated with the ultrasound triad of cyclopia, median
cleft lip, and microcephaly?
A. Holoprosencephaly
B. Fetal lithium exposure effects
C. Arnold-Chiari malformation
D. Meckel-Gruber syndrome
Answer: A. Holoprosencephaly
Explanation: Holoprosencephaly, resulting from failed cleavage of the prosencephalon during
early embryogenesis, presents with a spectrum of midline facial anomalies including cyclopia
(single midline orbit), median cleft lip and palate, and microcephaly. The severity correlates with
the degree of forebrain division failure. Alobar holoprosencephaly demonstrates the most severe
manifestations. While Meckel-Gruber syndrome may present with occipital encephalocele and
polydactyly, and Arnold-Chiari malformation is associated with neural tube defects, the specific
constellation of cyclopia, median cleft lip, and microcephaly is pathognomonic for
holoprosencephaly.
2026/2027: 50 High-Yield Questions with
Answers & Explanations | Fetal Anomalies,
Doppler, First-Trimester Screening &
Maternal-Fetal Medicine
Description:
Master the 2026/2027 Obstetrics and Gynecology Ultrasound board exam with this
comprehensive test bank featuring 50 expertly crafted multiple-choice questions covering fetal
anomalies, chromosomal abnormalities, twin pregnancy complications, Doppler
hemodynamics, first-trimester screening, placental pathology, and maternal-fetal medicine.
Each question includes detailed evidence-based explanations aligned with ISUOG, AIUM, and
ACOG guidelines. Updated for 2026/2027 academic standards, this resource is ideal for
medical students, residents, sonography trainees, and exam candidates preparing for board
certification.
Download now to maximize your exam readiness and achieve success in your OB/GYN ultrasound
rotation and certification examinations!
, OB/GYN Ultrasound Exam Prep 2026/2027
SECTION A: FIRST TRIMESTER ULTRASOUND AND GENETIC TESTING
Question 1
Which chromosomal abnormality demonstrates the strongest association with cystic hygromas
on prenatal ultrasound?
A. Trisomy 18
B. Trisomy 13
C. Turner syndrome (45,X)
D. Triploidy
Answer: C. Turner syndrome (45,X)
Explanation: Turner syndrome is the most frequently identified chromosomal abnormality
associated with cystic hygromas, which represent lymphatic malformations typically located in
the nuchal region. Approximately 75% of fetuses with Turner syndrome demonstrate cystic
hygromas on first-trimester ultrasound, making this finding a key diagnostic indicator. While
cystic hygromas may occasionally be observed in other aneuploidies including Trisomy 21,
Trisomy 18, and Trisomy 13, their prevalence in Turner syndrome is significantly higher and
clinically more specific.
Question 2
At which gestational age range is chorionic villus sampling (CVS) most appropriately performed
for routine prenatal genetic diagnosis?
A. 7-8 weeks
B. 10-13 weeks
C. 15-17 weeks
D. 19-22 weeks
Answer: B. 10-13 weeks
,Explanation: The optimal window for chorionic villus sampling is between 10 and 13 weeks of
gestation. This timeframe allows for adequate placental tissue development while minimizing
procedural risks. Early CVS (before 10 weeks) is associated with increased rates of fetal loss and
limb reduction defects, whereas CVS after 13 weeks poses greater technical challenges and may
be superseded by amniocentesis. Current 2026/2027 clinical guidelines recommend CVS
between 11 and 13+6 weeks, coinciding with the nuchal translucency screening window.
Question 3
A patient presents with vaginal bleeding and a serum beta-human chorionic gonadotropin level
of 35,000 mIU/mL. Transvaginal ultrasound reveals an empty uterine cavity and a complex
adnexal mass. Which diagnosis is most likely?
A. Molar pregnancy
B. Blighted ovum
C. Ectopic pregnancy
D. Missed abortion
Answer: C. Ectopic pregnancy
Explanation: The combination of elevated beta-hCG (35,000 mIU/mL), vaginal bleeding, an
empty uterus, and an adnexal mass is highly suggestive of an ectopic pregnancy. While beta-
hCG levels in ectopic pregnancies typically rise more slowly and plateau at lower levels than
normal intrauterine pregnancies, levels exceeding 30,000 mIU/mL can occur, particularly in
tubal ectopic pregnancies. The presence of an adnexal mass corresponding to the side of pain or
bleeding further supports this diagnosis. Molar pregnancies would demonstrate a characteristic
"snowstorm" appearance within the uterus, while blighted ovum and missed abortion would
show intrauterine findings.
Question 4
Which nuchal translucency measurement finding is most consistently associated with
chromosomally abnormal fetuses?
A. Normal measurement (<3.0 mm)
B. Increased measurement (≥3.5 mm)
, C. Absent nuchal translucency
D. Decreased measurement (<1.0 mm)
Answer: B. Increased measurement (≥3.5 mm)
Explanation: Increased nuchal translucency (NT) measurement, typically defined as ≥3.5 mm or
above the 95th percentile for gestational age, demonstrates a strong correlation with
chromosomal abnormalities, particularly Trisomy 21, Trisomy 18, and Turner syndrome. The
pathophysiological mechanism involves abnormal lymphatic drainage and increased interstitial
fluid accumulation. Current 2026/2027 guidelines recommend combined first-trimester screening
incorporating NT measurement, maternal serum biomarkers (PAPP-A and free β-hCG), maternal
age, and additional ultrasound markers to achieve detection rates exceeding 90% for Trisomy 21.
SECTION B: FETAL ANATOMY AND CENTRAL NERVOUS SYSTEM
Question 5
Which abnormality is most commonly associated with the ultrasound triad of cyclopia, median
cleft lip, and microcephaly?
A. Holoprosencephaly
B. Fetal lithium exposure effects
C. Arnold-Chiari malformation
D. Meckel-Gruber syndrome
Answer: A. Holoprosencephaly
Explanation: Holoprosencephaly, resulting from failed cleavage of the prosencephalon during
early embryogenesis, presents with a spectrum of midline facial anomalies including cyclopia
(single midline orbit), median cleft lip and palate, and microcephaly. The severity correlates with
the degree of forebrain division failure. Alobar holoprosencephaly demonstrates the most severe
manifestations. While Meckel-Gruber syndrome may present with occipital encephalocele and
polydactyly, and Arnold-Chiari malformation is associated with neural tube defects, the specific
constellation of cyclopia, median cleft lip, and microcephaly is pathognomonic for
holoprosencephaly.
