RDMS – Registered Diagnostic Medical Sonographer
Board Certification Exam Updated 2026 | 550+
Practice Questions & Verified Answers | Advanced
Ultrasound Registry Study Guide, Comprehensive
Diagnostic Sonography Exam Prep, Abdomen,
OB/GYN, Vascular & Small Parts Imaging,
Ultrasound Physics, Doppler Imaging, Image
Optimization, Patient Safety, Cross-Sectional
Anatomy, Detailed Rationales
Question 1: According to the AIUM standard practice guidelines, what is the
minimum frequency recommended for transvaginal sonography in early
pregnancy assessment?
A. 2.5 MHz
B. 3.5 MHz
C. 5.0 MHz
D. 7.5 MHz
CORRECT ANSWER: C. 5.0 MHz
Rationale: The AIUM recommends a minimum frequency of 5.0 MHz for transvaginal
sonography to achieve the necessary spatial resolution for evaluating early gestational
structures. Higher frequencies provide better near-field resolution, which is critical for
transvaginal imaging due to the proximity of the transducer to the target anatomy.
Question 2: In spectral Doppler analysis of the umbilical artery, a persistently
absent or reversed end-diastolic flow (AREDF) is most commonly associated
with which of the following conditions?
A. Maternal pre-eclampsia
B. Placental insufficiency
C. Fetal tachycardia
D. Polyhydramnios
CORRECT ANSWER: B. Placental insufficiency
Rationale: Absent or reversed end-diastolic flow in the umbilical artery indicates high
placental resistance, which is the hallmark of placental insufficiency. This finding is
associated with intrauterine growth restriction (IUGR) and fetal hypoxia, often requiring
close antenatal surveillance.
Question 3: Which of the following ultrasound findings is considered a major
criterion for the diagnosis of Polycystic Ovarian Syndrome (PCOS) according to
the Rotterdam criteria?
A. Ovarian volume less than 5 cm³
B. Presence of a single dominant follicle
,C. 12 or more follicles measuring 2-9 mm in diameter in one ovary
D. Unilocular anechoic cyst measuring 3 cm
CORRECT ANSWER: C. 12 or more follicles measuring 2-9 mm in diameter in
one ovary
Rationale: The Rotterdam criteria for PCOS include the presence of 12 or more follicles
(2-9 mm) or an ovarian volume >10 cm³ in at least one ovary, along with clinical or
biochemical hyperandrogenism and/or oligo-ovulation.
Question 4: What is the primary sonographic feature that differentiates a
hydatidiform mole from a missed abortion?
A. Presence of a fetal pole
B. "Snowstorm" or vesicular pattern with no identifiable fetus
C. Increased amniotic fluid volume
D. Decreased maternal serum beta-hCG levels
CORRECT ANSWER: B. "Snowstorm" or vesicular pattern with no identifiable
fetus
Rationale: A complete hydatidiform mole typically presents with a characteristic
"snowstorm" appearance on ultrasound due to the hydropic swelling of chorionic villi,
without an identifiable fetus. A missed abortion usually shows a gestational sac with a
non-viable embryo.
Question 5: To accurately measure the fetal biparietal diameter (BPD) after 14
weeks of gestation, the correct plane of section must include which of the
following?
A. Cavum septum pellucidum and thalami
B. Cisterna magna and cerebellum
C. Transverse view of the fetal abdomen
D. Four-chamber view of the heart
CORRECT ANSWER: A. Cavum septum pellucidum and thalami
Rationale: The standard plane for BPD measurement is the transthalamic plane, which
should include the midline falx, the cavum septum pellucidum in the anterior third, the
thalami, and the third ventricle. The cerebellum and cisterna magna are used for the
transcerebellar plane.
Question 6: In the first trimester, the crown-rump length (CRL) measurement is
most accurate for dating between which gestational age range?
A. 5 to 6 weeks
B. 7 to 10 weeks
C. 11 to 13 weeks + 6 days
D. 14 to 16 weeks
CORRECT ANSWER: B. 7 to 10 weeks
,Rationale: The CRL is most accurate for dating between 7 and 10 weeks of gestation,
with an accuracy of ±3 to 5 days. Before 7 weeks, it is less reliable; after 13 weeks, other
parameters like BPD and head circumference (HC) are preferred.
Question 7: Which of the following congenital anomalies is characterized by
the absence of the corpus callosum, often resulting in a "steer-horn" or "Viking
helmet" configuration of the lateral ventricles?
A. Dandy-Walker malformation
B. Holoprosencephaly
C. Agenesis of the corpus callosum
D. Chiari II malformation
CORRECT ANSWER: C. Agenesis of the corpus callosum
Rationale: Agenesis of the corpus callosum leads to parallel, widely separated lateral
ventricles with a "steer-horn" appearance in the coronal plane. Dandy-Walker involves
the posterior fossa, and holoprosencephaly involves failure of the forebrain to divide.
Question 8: A patient with acute pelvic pain presents for a transvaginal
ultrasound. The right adnexa shows a complex, ring-like structure with
peripheral vascularity ("ring of fire" sign). What is the most likely diagnosis?
A. Ovarian cyst
B. Ectopic pregnancy
C. Tubo-ovarian abscess
D. Ovarian torsion
CORRECT ANSWER: B. Ectopic pregnancy
Rationale: The "ring of fire" sign on Doppler represents high-velocity, low-resistance
flow around an extrauterine gestational sac, which is highly suggestive of an ectopic
pregnancy. This is distinct from a corpus luteum cyst, though similar flow may be seen.
Question 9: What is the normal sonographic appearance of the first-trimester
yolk sac?
A. A thin-walled, echogenic ring within the chorionic sac
B. A thick-walled, irregular, calcified structure
C. A large, septated cystic structure adjacent to the embryo
D. A small, echogenic, mobile focus within the amniotic cavity
CORRECT ANSWER: A. A thin-walled, echogenic ring within the chorionic sac
Rationale: The yolk sac appears as a thin-walled, spherical, echogenic ring structure
located within the chorionic cavity. It is the first structure visible within the gestational
sac and provides nourishment to the embryo before the placental circulation is
established.
, Question 10: In a patient with suspected deep vein thrombosis (DVT) of the
lower extremity, which of the following Doppler findings is most indicative of
acute thrombus formation?
A. Complete collapse of the vein with probe pressure
B. Absent flow and a non-compressible vein
C. Respiratory phasicity in the iliac veins
D. Monophasic flow pattern with augmentation
CORRECT ANSWER: B. Absent flow and a non-compressible vein
Rationale: The inability to completely compress the vein with transducer pressure is the
most sensitive and specific gray-scale criterion for acute DVT. This is often accompanied
by absent or diminished spectral Doppler flow.
Question 11: During a fetal echocardiogram, the "V-sign" is a sonographic
landmark used to identify which of the following?
A. The aortic and pulmonary valves
B. The descending aorta and inferior vena cava
C. The left ventricular outflow tract
D. The four-chamber view
CORRECT ANSWER: A. The aortic and pulmonary valves
Rationale: The "V-sign" is formed by the simultaneous visualization of the aortic and
pulmonary valves in a short-axis view of the fetal heart. It is a useful marker to confirm
the normal relationship of the great arteries.
Question 12: Which of the following parameters is NOT a standard component
of the biophysical profile (BPP)?
A. Fetal breathing movements
B. Fetal tone
C. Amniotic fluid volume
D. Placental grading
CORRECT ANSWER: D. Placental grading
Rationale: The biophysical profile includes fetal breathing movements, fetal tone, fetal
movement, amniotic fluid volume, and the non-stress test (NST). Placental grading is a
separate assessment of placental maturity and is not part of the BPP scoring system.
Question 13: The "double bleb" sign, seen in early pregnancy, refers to which
two structures?
A. The yolk sac and the embryo
B. The chorionic cavity and the amniotic cavity
C. The yolk sac and the chorionic cavity
D. The decidua basalis and the decidua capsularis
Board Certification Exam Updated 2026 | 550+
Practice Questions & Verified Answers | Advanced
Ultrasound Registry Study Guide, Comprehensive
Diagnostic Sonography Exam Prep, Abdomen,
OB/GYN, Vascular & Small Parts Imaging,
Ultrasound Physics, Doppler Imaging, Image
Optimization, Patient Safety, Cross-Sectional
Anatomy, Detailed Rationales
Question 1: According to the AIUM standard practice guidelines, what is the
minimum frequency recommended for transvaginal sonography in early
pregnancy assessment?
A. 2.5 MHz
B. 3.5 MHz
C. 5.0 MHz
D. 7.5 MHz
CORRECT ANSWER: C. 5.0 MHz
Rationale: The AIUM recommends a minimum frequency of 5.0 MHz for transvaginal
sonography to achieve the necessary spatial resolution for evaluating early gestational
structures. Higher frequencies provide better near-field resolution, which is critical for
transvaginal imaging due to the proximity of the transducer to the target anatomy.
Question 2: In spectral Doppler analysis of the umbilical artery, a persistently
absent or reversed end-diastolic flow (AREDF) is most commonly associated
with which of the following conditions?
A. Maternal pre-eclampsia
B. Placental insufficiency
C. Fetal tachycardia
D. Polyhydramnios
CORRECT ANSWER: B. Placental insufficiency
Rationale: Absent or reversed end-diastolic flow in the umbilical artery indicates high
placental resistance, which is the hallmark of placental insufficiency. This finding is
associated with intrauterine growth restriction (IUGR) and fetal hypoxia, often requiring
close antenatal surveillance.
Question 3: Which of the following ultrasound findings is considered a major
criterion for the diagnosis of Polycystic Ovarian Syndrome (PCOS) according to
the Rotterdam criteria?
A. Ovarian volume less than 5 cm³
B. Presence of a single dominant follicle
,C. 12 or more follicles measuring 2-9 mm in diameter in one ovary
D. Unilocular anechoic cyst measuring 3 cm
CORRECT ANSWER: C. 12 or more follicles measuring 2-9 mm in diameter in
one ovary
Rationale: The Rotterdam criteria for PCOS include the presence of 12 or more follicles
(2-9 mm) or an ovarian volume >10 cm³ in at least one ovary, along with clinical or
biochemical hyperandrogenism and/or oligo-ovulation.
Question 4: What is the primary sonographic feature that differentiates a
hydatidiform mole from a missed abortion?
A. Presence of a fetal pole
B. "Snowstorm" or vesicular pattern with no identifiable fetus
C. Increased amniotic fluid volume
D. Decreased maternal serum beta-hCG levels
CORRECT ANSWER: B. "Snowstorm" or vesicular pattern with no identifiable
fetus
Rationale: A complete hydatidiform mole typically presents with a characteristic
"snowstorm" appearance on ultrasound due to the hydropic swelling of chorionic villi,
without an identifiable fetus. A missed abortion usually shows a gestational sac with a
non-viable embryo.
Question 5: To accurately measure the fetal biparietal diameter (BPD) after 14
weeks of gestation, the correct plane of section must include which of the
following?
A. Cavum septum pellucidum and thalami
B. Cisterna magna and cerebellum
C. Transverse view of the fetal abdomen
D. Four-chamber view of the heart
CORRECT ANSWER: A. Cavum septum pellucidum and thalami
Rationale: The standard plane for BPD measurement is the transthalamic plane, which
should include the midline falx, the cavum septum pellucidum in the anterior third, the
thalami, and the third ventricle. The cerebellum and cisterna magna are used for the
transcerebellar plane.
Question 6: In the first trimester, the crown-rump length (CRL) measurement is
most accurate for dating between which gestational age range?
A. 5 to 6 weeks
B. 7 to 10 weeks
C. 11 to 13 weeks + 6 days
D. 14 to 16 weeks
CORRECT ANSWER: B. 7 to 10 weeks
,Rationale: The CRL is most accurate for dating between 7 and 10 weeks of gestation,
with an accuracy of ±3 to 5 days. Before 7 weeks, it is less reliable; after 13 weeks, other
parameters like BPD and head circumference (HC) are preferred.
Question 7: Which of the following congenital anomalies is characterized by
the absence of the corpus callosum, often resulting in a "steer-horn" or "Viking
helmet" configuration of the lateral ventricles?
A. Dandy-Walker malformation
B. Holoprosencephaly
C. Agenesis of the corpus callosum
D. Chiari II malformation
CORRECT ANSWER: C. Agenesis of the corpus callosum
Rationale: Agenesis of the corpus callosum leads to parallel, widely separated lateral
ventricles with a "steer-horn" appearance in the coronal plane. Dandy-Walker involves
the posterior fossa, and holoprosencephaly involves failure of the forebrain to divide.
Question 8: A patient with acute pelvic pain presents for a transvaginal
ultrasound. The right adnexa shows a complex, ring-like structure with
peripheral vascularity ("ring of fire" sign). What is the most likely diagnosis?
A. Ovarian cyst
B. Ectopic pregnancy
C. Tubo-ovarian abscess
D. Ovarian torsion
CORRECT ANSWER: B. Ectopic pregnancy
Rationale: The "ring of fire" sign on Doppler represents high-velocity, low-resistance
flow around an extrauterine gestational sac, which is highly suggestive of an ectopic
pregnancy. This is distinct from a corpus luteum cyst, though similar flow may be seen.
Question 9: What is the normal sonographic appearance of the first-trimester
yolk sac?
A. A thin-walled, echogenic ring within the chorionic sac
B. A thick-walled, irregular, calcified structure
C. A large, septated cystic structure adjacent to the embryo
D. A small, echogenic, mobile focus within the amniotic cavity
CORRECT ANSWER: A. A thin-walled, echogenic ring within the chorionic sac
Rationale: The yolk sac appears as a thin-walled, spherical, echogenic ring structure
located within the chorionic cavity. It is the first structure visible within the gestational
sac and provides nourishment to the embryo before the placental circulation is
established.
, Question 10: In a patient with suspected deep vein thrombosis (DVT) of the
lower extremity, which of the following Doppler findings is most indicative of
acute thrombus formation?
A. Complete collapse of the vein with probe pressure
B. Absent flow and a non-compressible vein
C. Respiratory phasicity in the iliac veins
D. Monophasic flow pattern with augmentation
CORRECT ANSWER: B. Absent flow and a non-compressible vein
Rationale: The inability to completely compress the vein with transducer pressure is the
most sensitive and specific gray-scale criterion for acute DVT. This is often accompanied
by absent or diminished spectral Doppler flow.
Question 11: During a fetal echocardiogram, the "V-sign" is a sonographic
landmark used to identify which of the following?
A. The aortic and pulmonary valves
B. The descending aorta and inferior vena cava
C. The left ventricular outflow tract
D. The four-chamber view
CORRECT ANSWER: A. The aortic and pulmonary valves
Rationale: The "V-sign" is formed by the simultaneous visualization of the aortic and
pulmonary valves in a short-axis view of the fetal heart. It is a useful marker to confirm
the normal relationship of the great arteries.
Question 12: Which of the following parameters is NOT a standard component
of the biophysical profile (BPP)?
A. Fetal breathing movements
B. Fetal tone
C. Amniotic fluid volume
D. Placental grading
CORRECT ANSWER: D. Placental grading
Rationale: The biophysical profile includes fetal breathing movements, fetal tone, fetal
movement, amniotic fluid volume, and the non-stress test (NST). Placental grading is a
separate assessment of placental maturity and is not part of the BPP scoring system.
Question 13: The "double bleb" sign, seen in early pregnancy, refers to which
two structures?
A. The yolk sac and the embryo
B. The chorionic cavity and the amniotic cavity
C. The yolk sac and the chorionic cavity
D. The decidua basalis and the decidua capsularis
