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C) Triangular
D) Flattened
Explanation:
A normal gestational sac is round or ovoid with a well-defined echogenic border. Irregular or flattened sacs may indicate a failing pregnancy or implantation issues.
Answer: B) Ovoid or round
2. Which of the following is an ultrasound sign of an abnormal gestational sac?
A) Double decidual sac sign
B) Regular, well-defined borders
C) Irregular shape and poorly defined borders
D) Central implantation of the sac
Answer: C) Irregular shape and poorly defined borders
Explanation:
An abnormal gestational sac appears irregular, with a thin or poorly defined echogenic border. A normal gestational sac exhibits a double decidual sign, which confirms an intrauterine pregnancy.
3. A gestational sac should be visible on transvaginal ultrasound at what β-hCG level?
A) 500 mIU/mL
B) 1000-1500 mIU/mL
C) 2500-3000 mIU/mL
D) 4000-5000 mIU/mL
Explanation:
The discriminatory zone for detecting a gestational sac on transvaginal ultrasound is typically when β-hCG is ≥ 1500 mIU/mL. If no gestational sac is seen above this level, ectopic pregnancy or early pregnancy failure should be considered.
Answer: B) 1000-1500 mIU/mL
4. What is considered an abnormally large yolk sac measurement on ultrasound?
A) >2 mm
B) >5 mm
C) >7 mm
D) >10 mm
Explanation:
A yolk sac >5 mm is associated with an increased risk of pregnancy failure. The yolk sac provides nutrients to the embryo, and an abnormally large yolk sac often indicates poor embryonic development.
Answer: B) >5 mm
5. What is a concerning feature of a gestational sac in early pregnancy?
A) Double decidual sign
B) Echogenic ring around the sac
C) Absence of yolk sac with mean sac diameter >25 mm
D) Increased vascularity
Explanation:
A gestational sac with MSD (mean sac diameter) ≥25 mm without a yolk sac or embryo is diagnostic of pregnancy failure (anembryonic pregnancy). A normal yolk sac should be visible when the MSD reaches ≥10 mm.
Answer: C) Absence of yolk sac with mean sac diameter >25 mm
6. Which of the following is NOT a feature of an anembryonic pregnancy?
A) Large gestational sac without an embryo
B) Mean sac diameter >25 mm with no fetal pole
C) Normal yolk sac and fetal heartbeat
D) Absence of fetal pole after expected development period
Explanation:
An anembryonic pregnancy (blighted ovum) is characterized by a gestational sac without an embryo. The presence of a yolk sac and fetal heartbeat confirms an ongoing pregnancy.
Answer: C) Normal yolk sac and fetal heartbeat
7. What is the typical ultrasound feature of a blighted ovum?
A) Normal yolk sac and fetal heartbeat
B) Enlarged, empty gestational sac
C) Thick-walled cystic mass
D) Hypervascular ring
Explanation:
A blighted ovum (anembryonic pregnancy) appears as a large, empty gestational sac without a fetal pole. It occurs when the embryo fails to develop despite implantation.
Answer: B) Enlarged, empty gestational sac
8. Which feature on ultrasound suggests a failed early pregnancy?
A) Gestational sac without a yolk sac at 5 weeks
B) No fetal heartbeat at 6 weeks
C) Mean sac diameter of 25 mm with no embryo
D) Normal growth of the gestational sac over a week
Explanation:
An MSD ≥ 25 mm without an embryo is a definitive sign of pregnancy failure. A yolk sac is typically seen at MSD ≥10 mm, and an embryo with cardiac activity should be present by MSD ≥25 mm.
Answer: C) Mean sac diameter of 25 mm with no embryo
9. Which of the following is an abnormal feature of a gestational sac on ultrasound?
A) Central implantation
B) Double decidual ring
C) Mean sac diameter increasing by 1 mm/day
D) Round or oval shape
Explanation:
A normally implanted gestational sac should be eccentrically located within the endometrial cavity. Central implantation may indicate an abnormal pregnancy, such as a cesarean scar pregnancy or a failed pregnancy.
Answer: A) Central implantation
10. When should a fetal heartbeat be detected on transvaginal ultrasound?
A) At 4 weeks
B) At 5 weeks
C) At 6 weeks
D) At 8 weeks
Explanation:
A fetal heartbeat is typically detectable by 6 weeks of gestation on transvaginal ultrasound. If no heartbeat is detected at 7 weeks with a crown-rump length (CRL) ≥7 mm, pregnancy failure is suspected.
Answer: C) At 6 weeks
11. What is the earliest ultrasound sign of an intrauterine pregnancy?
A) Fetal pole
B) Yolk sac
C) Double decidual sac sign
D) Cardiac activity
Explanation:
The double decidual sac sign (DDSS) is the first reliable ultrasound feature of an intrauterine pregnancy, appearing as two echogenic rings surrounding the gestational sac. It helps differentiate a normal intrauterine pregnancy from a pseudogestational sac seen in ectopic pregnancy.
Answer: C) Double decidual sac sign
12. Which measurement is considered diagnostic of early pregnancy failure in the absence of cardiac activity?
A) Crown-rump length (CRL) ≥7 mm
B) Mean sac diameter (MSD) ≥15 mm
C) Yolk sac >3 mm
D) MSD growing <1 mm/day
Explanation:
A CRL ≥7 mm without cardiac activity is diagnostic of pregnancy failure. The MSD criterion is ≥25 mm without an embryo. These cutoffs help avoid misdiagnosing a viable pregnancy as a failed one.
Answer: A) Crown-rump length (CRL) ≥7 mm
13. A gestational sac located in the lower uterine segment is concerning for which condition?
A) Normal pregnancy
B) Ectopic pregnancy
C) Cervical pregnancy
D) Molar pregnancy
Explanation:
A cervical pregnancy is an abnormally implanted pregnancy in the cervix instead of the uterine cavity. It can be mistaken for a spontaneous abortion in progress but is diagnosed when the gestational sac is seen within the cervical canal on ultrasound.
Answer: C) Cervical pregnancy
14. What is the normal growth rate of the gestational sac in early pregnancy?
A) 0.5 mm/day
B) 1 mm/day
C) 2 mm/day
D) 3 mm/day
Answer: B) 1 mm/day
Explanation:
A normally developing gestational sac grows at an average rate of 1 mm per day in early pregnancy. Failure of normal sac growth is a sign of early pregnancy failure.
15. A gestational sac without an embryo is normal up to which gestational age?
A) 5 weeks
B) 6 weeks
C) 7 weeks
D) 8 weeks
Explanation:
A gestational sac without an embryo is normal before 6 weeks of pregnancy. By 6 weeks, a fetal pole should be visible, and by 7 weeks, cardiac activity should be detected. Persistent absence of an embryo at MSD ≥25 mm is diagnostic of an anembryonic pregnancy.
Answer: B) 6 weeks
16. What ultrasound sign is associated with a threatened miscarriage?
A) Increased amniotic fluid
B) Normal fetal heartbeat with subchorionic hemorrhage
C) Irregularly shaped gestational sac
D) Empty gestational sac with a large yolk sac
Explanation:
A threatened miscarriage is diagnosed when there is vaginal bleeding but with a viable embryo and fetal heartbeat. Subchorionic hemorrhage (SCH), seen as a hypoechoic area near the gestational sac, is commonly associated with this condition.
Answer: B) Normal fetal heartbeat with subchorionic hemorrhage
17. Which ultrasound finding suggests a nonviable pregnancy?
A) Gestational sac located in the fundus
B) MSD 16 mm without a yolk sac
C) Gestational sac with a well-defined decidual reaction
D) CRL of 4 mm with detectable cardiac activity
Explanation:
A MSD ≥16 mm without a yolk sac suggests pregnancy failure. Definitive criteria for nonviability include MSD ≥25 mm without an embryo or CRL ≥7 mm without cardiac activity.
Answer: B) MSD 16 mm without a yolk sac
18. Which ultrasound finding is most suggestive of an ectopic pregnancy?
A) Double decidual sac sign
B) Empty uterus with β-hCG >2000 mIU/mL
C) Yolk sac without an embryo
D) MSD >25 mm without a fetal pole
Explanation:
An empty uterus despite β-hCG >2000 mIU/mL is highly suggestive of an ectopic pregnancy. A normal intrauterine pregnancy should be seen by this hCG level on transvaginal ultrasound.
Answer: B) Empty uterus with β-hCG >2000 mIU/mL
19. Which of the following is a poor prognostic sign in early pregnancy?
A) Yolk sac measuring 3 mm
B) Gestational sac located in the fundus
C) Irregular gestational sac with a thin decidual reaction
D) Double decidual sac sign
Explanation:
A thin decidual reaction (<2 mm) with an irregular sac is a poor prognostic sign and suggests impending pregnancy failure. A strong decidual reaction is needed for proper implantation and support of the embryo.
Answer: C) Irregular gestational sac with a thin decidual reaction
20. What does the "trophoblastic ring sign" indicate in early pregnancy?
A) Ectopic pregnancy
B) Normal intrauterine pregnancy
C) Blighted ovum
D) Molar pregnancy
Explanation:
The trophoblastic ring sign refers to a hyperechoic ring surrounding a gestational sac in an ectopic pregnancy. This is different from the double decidual sac sign seen in normal intrauterine pregnancies.
Answer: A) Ectopic pregnancy
21. In cases of early pregnancy failure, what is the recommended follow-up interval for repeat ultrasound?
A) 24 hours
B) 48 hours
C) 7-10 days
D) 2-3 weeks
Explanation:
In cases of uncertain viability, a repeat ultrasound in 7-10 days is recommended to confirm progression or pregnancy failure. If there is no growth or heartbeat, the pregnancy is considered nonviable.
Answer: C) 7-10 days
22. A "collapsed gestational sac" on ultrasound is a feature of which condition?
A) Threatened miscarriage
B) Incomplete abortion
C) Ectopic pregnancy
D) Anembryonic pregnancy
Explanation:
A collapsed gestational sac with retained products of conception (POC) suggests an incomplete abortion. It is seen when fetal demise has occurred, and the sac begins to break down or expel.
Answer: B) Incomplete abortion
23. What is the earliest structure seen within the gestational sac on ultrasound?
A) Embryo
B) Yolk sac
C) Amniotic sac
D) Placenta
Explanation:
The yolk sac is the first structure seen within the gestational sac, usually by 5-6 weeks of gestation. The yolk sac provides early nutrition to the embryo.
Answer: B) Yolk sac
24. What is an important sonographic feature distinguishing a pseudogestational sac from a true gestational sac?
A) Round shape
B) Location within the uterine cavity
C) Double decidual sac sign
D) No yolk sac
Explanation:
A true gestational sac has a double decidual sac sign (DDSS) and is eccentrically placed within the endometrium. A pseudogestational sac, often seen in ectopic pregnancy, is centrally located and lacks the DDSS.
Answer: C) Double decidual sac sign
25. What is the normal sonographic appearance of the gestational sac at 5 weeks?
A) An anechoic sac with a thick echogenic border
B) A solid hyperechoic structure
C) A cystic structure with an internal embryo
D) A hypoechoic ring-like structure
Explanation:
At 5 weeks, the gestational sac appears as a round, anechoic structure with a thick echogenic border (representing the decidua).
Answer: A) An anechoic sac with a thick echogenic border
26. What is the normal relationship between the yolk sac and amniotic sac?
A) The yolk sac is inside the amniotic sac
B) The amniotic sac is inside the yolk sac
C) They are separate structures, but the yolk sac disappears as the amniotic sac enlarges
D) The yolk sac remains visible throughout pregnancy
Explanation:
The yolk sac and amniotic sac are separate. As pregnancy progresses, the yolk sac shrinks and eventually disappears, while the amniotic sac enlarges to surround the embryo.
Answer: C) They are separate structures, but the yolk sac disappears as the amniotic sac enlarges
27. What is the normal mean sac diameter (MSD) for a 6-week gestation?
A) 5-10 mm
B) 10-15 mm
C) 16-20 mm
D) 25 mm
Explanation:
At 6 weeks, the MSD is usually 10-15 mm. The gestational sac should grow approximately 1 mm per day.
Answer: B) 10-15 mm
28. What is an ultrasound feature of a gestational sac in an ectopic pregnancy?
A) Double decidual sign
B) Central location in the uterus
C) Empty uterine cavity with an adnexal mass
D) Presence of a fetal pole in the endometrial cavity
Explanation:
An ectopic pregnancy is suggested when no intrauterine gestational sac is seen, and an adnexal mass (often with a ring-like structure) is present.
Answer: C) Empty uterine cavity with an adnexal mass
29. If a yolk sac is absent when the MSD is >10 mm, what is the likely diagnosis?
A) Normal pregnancy
B) Molar pregnancy
C) Early pregnancy failure
D) Cervical pregnancy
Explanation:
A yolk sac should be present when the MSD reaches ≥10 mm. Absence of a yolk sac at this size increases the risk of early pregnancy failure.
Answer: C) Early pregnancy failure
30. What does an enlarged and calcified yolk sac suggest?
A) Ectopic pregnancy
B) Normal pregnancy progression
C) Fetal demise
D) Molar pregnancy
Explanation:
An enlarged (>5 mm) and calcified yolk sac is an ominous sign, often indicating fetal demise or pregnancy failure.
Answer: C) Fetal demise
31. The presence of a gestational sac in the cornual region of the uterus is concerning for what condition?
A) Normal intrauterine pregnancy
B) Molar pregnancy
C) Cornual (interstitial) ectopic pregnancy
D) Cervical pregnancy
Explanation:
A cornual ectopic pregnancy occurs when the gestational sac implants in the interstitial (cornual) portion of the fallopian tube. This is a high-risk pregnancy due to potential rupture and massive hemorrhage.
Answer: C) Cornual (interstitial) ectopic pregnancy
32. What is the expected location of a normal gestational sac on ultrasound?
A) Within the endometrial stripe
B) Eccentric position in the endometrium
C) Low in the cervix
D) Near the myometrium
Explanation:
A normal gestational sac is eccentrically positioned in the endometrium (not in the center). A centrally placed sac may suggest a pseudogestational sac (common in ectopic pregnancies).
Answer: B) Eccentric position in the endometrium
33. Which of the following findings is most suggestive of a molar pregnancy?
A) Normal gestational sac with a yolk sac
B) Enlarged, echogenic placenta with multiple cystic spaces
C) Empty gestational sac with a small yolk sac
D) Adnexal mass with no intrauterine sac
Explanation:
A molar pregnancy (gestational trophoblastic disease) appears as an enlarged placenta with multiple small cystic spaces, sometimes described as a "snowstorm" appearance.
Answer: B) Enlarged, echogenic placenta with multiple cystic spaces
34. If a fetal heartbeat is absent at 7 weeks with a CRL of 8 mm, what is the most likely diagnosis?
A) Normal early pregnancy
B) Missed miscarriage
C) Threatened miscarriage
D) Blighted ovum
Explanation:
A missed miscarriage is diagnosed when an embryo with CRL ≥7 mm has no detectable cardiac activity.
Answer: B) Missed miscarriage
35. Which of the following factors increases the risk of an anembryonic pregnancy?
A) Advanced maternal age
B) Multiple gestation
C) History of molar pregnancy
D) All of the above
Explanation:
Risk factors for anembryonic pregnancy (blighted ovum) include advanced maternal age, prior miscarriage, chromosomal abnormalities, multiple gestations, and trophoblastic disease.
Answer: D) All of the above
36. What is the purpose of serial β-hCG measurements in early pregnancy assessment?
A) To detect gestational diabetes
B) To evaluate fetal growth
C) To confirm a normal pregnancy trend
D) To assess placental function
Explanation:
Serial β-hCG measurements help determine pregnancy viability. In a normal pregnancy, β-hCG doubles every 48-72 hours. Failure to rise appropriately suggests ectopic pregnancy or early pregnancy failure.
Answer: C) To confirm a normal pregnancy trend
37. What is the most accurate way to determine early pregnancy failure using the mean sac diameter (MSD)?
A) MSD ≥10 mm with no yolk sac
B) MSD ≥16 mm with no embryo
C) MSD ≥25 mm with no embryo
D) MSD growing less than 1 mm per day
Explanation:
A mean sac diameter (MSD) of ≥25 mm without an embryo is diagnostic of early pregnancy failure. Prior to reaching this size, follow-up ultrasounds are required for confirmation.
Answer: C) MSD ≥25 mm with no embryo
38. Which of the following features is NOT suggestive of an abnormal gestational sac?
A) Irregular sac shape
B) Thin decidual reaction
C) Central implantation within the endometrium
D) Round and well-defined sac with a double decidual sign
Explanation:
A round, well-defined gestational sac with a double decidual sign is a reassuring feature of a normal intrauterine pregnancy. Abnormal features include an irregular shape, thin decidua, and central implantation.
Answer: D) Round and well-defined sac with a double decidual sign
39. A gestational sac with a disproportionately large yolk sac (>7 mm) is concerning for:
A) Normal pregnancy
B) Increased risk of miscarriage
C) Multiple gestation
D) Molar pregnancy
Explanation:
A yolk sac larger than 7 mm is an indicator of poor pregnancy prognosis and is associated with a higher risk of spontaneous miscarriage.
Answer: B) Increased risk of miscarriage
40. What ultrasound feature helps differentiate a gestational sac from a fluid-filled uterine cavity?
A) Echogenic border
B) Anechoic center
C) Location in the cervix
D) Irregular shape
Explanation:
A true gestational sac has a thick echogenic border due to trophoblastic reaction. A fluid-filled endometrial cavity (e.g., blood collection) does not have this feature.
Answer: A) Echogenic border
41. Which ultrasound sign indicates an impending miscarriage?
A) Expanding gestational sac with a thick decidual reaction
B) Large yolk sac with a collapsed gestational sac
C) Gestational sac growing at 1 mm/day
D) Well-formed yolk sac and fetal pole
Explanation:
A large yolk sac (>7 mm) with a collapsed gestational sac suggests pregnancy failure. Normally, the gestational sac should expand and remain well-defined.
Answer: B) Large yolk sac with a collapsed gestational sac
42. What is the normal cutoff for visualizing a fetal heartbeat on transvaginal ultrasound?
A) CRL ≥2 mm
B) CRL ≥4 mm
C) CRL ≥7 mm
D) CRL ≥10 mm
Explanation:
A fetal heartbeat should be detected when the CRL reaches ≥7 mm. If no cardiac activity is seen at this stage, pregnancy failure is confirmed.
Answer: C) CRL ≥7 mm
43. Which of the following is a classic ultrasound finding of a blighted ovum (anembryonic pregnancy)?
A) Empty gestational sac with MSD ≥25 mm
B) Double decidual sac sign
C) Gestational sac with fetal pole and cardiac activity
D) Thick echogenic trophoblastic ring
Explanation:
A blighted ovum (anembryonic pregnancy) occurs when the gestational sac forms, but no embryo develops. Diagnosis is confirmed if MSD ≥25 mm with no fetal pole.
Answer: A) Empty gestational sac with MSD ≥25 mm
44. What is the best next step if a gestational sac is seen but no yolk sac or fetal pole is present?
A) Immediate diagnosis of miscarriage
B) Repeat ultrasound in 7-10 days
C) Prescribe progesterone
D) Surgical evacuation
Explanation:
If the gestational sac is present but no yolk sac or fetal pole is visible, it may simply be too early. A repeat ultrasound in 7-10 days can confirm viability or failure.
Answer: B) Repeat ultrasound in 7-10 days
45. What is the most likely cause of an empty gestational sac with a thick trophoblastic ring and no embryo?
A) Blighted ovum
B) Normal early pregnancy
C) Ectopic pregnancy
D) Molar pregnancy
Explanation:
A blighted ovum appears as a gestational sac without an embryo but with a thick trophoblastic ring. The trophoblast continues growing despite embryonic arrest.
Answer: A) Blighted ovum
46. Which of the following is an indicator of an ectopic pregnancy?
A) Intrauterine gestational sac with a yolk sac
B) Empty uterus with β-hCG >2000 mIU/mL
C) MSD of 10 mm with no fetal pole
D) CRL of 5 mm with cardiac activity
Explanation:
An empty uterus with β-hCG >2000 mIU/mL is highly suggestive of an ectopic pregnancy because an intrauterine pregnancy should be visible at this hCG level.
Answer: B) Empty uterus with β-hCG >2000 mIU/mL
47. What is the characteristic ultrasound finding of a cervical pregnancy?
A) Gestational sac in the endometrial cavity
B) Empty uterus with an adnexal mass
C) Gestational sac within the cervical canal
D) Hypervascular "snowstorm" appearance
Explanation:
A cervical pregnancy is diagnosed when a gestational sac implants in the cervical canal, which can lead to severe bleeding if disrupted.
Answer: C) Gestational sac within the cervical canal
48. What is the normal range for the yolk sac diameter in early pregnancy?
A) 1-2 mm
B) 3-5 mm
C) 6-8 mm
D) 9-12 mm
Explanation:
The normal yolk sac diameter is 3-5 mm. A yolk sac >7 mm is abnormal and increases the risk of pregnancy loss.
Answer: B) 3-5 mm
49. If the gestational sac is growing <1 mm/day, what does it indicate?
A) Normal pregnancy
B) Risk of early pregnancy failure
C) Multiple gestation
D) Molar pregnancy
Explanation:
A normal gestational sac grows ~1 mm per day. A growth rate <1 mm/day suggests poor viability and possible pregnancy failure.
Answer: B) Risk of early pregnancy failure
50. What is the ultrasound sign of a complete molar pregnancy?
A) Snowstorm appearance with no embryo
B) Gestational sac with fetal pole
C) Normal amniotic sac with a yolk sac
D) Thin-walled empty sac
Explanation:
A complete molar pregnancy is characterized by a "snowstorm" appearance, with no embryo and numerous hydropic villi replacing normal placental tissue.
Answer: A) Snowstorm appearance with no embryo
51. What is the normal range for the embryonic heart rate (EHR) at 6-7 weeks gestation?
A) 60-90 bpm
B) 100-120 bpm
C) 120-160 bpm
D) 170-200 bpm
Explanation:
The normal embryonic heart rate (EHR) starts around 100-120 bpm at 6-7 weeks and increases to 120-160 bpm by 8-10 weeks. A rate <90 bpm suggests a poor prognosis.
Answer: B) 100-120 bpm
52. A crown-rump length (CRL) of 7 mm with no cardiac activity is diagnostic of:
A) Normal early pregnancy
B) Threatened miscarriage
C) Embryonic demise
D) Blighted ovum
Explanation:
A CRL of ≥7 mm without a heartbeat confirms embryonic demise (missed miscarriage) on ultrasound. A repeat scan in a few days may be done to confirm.
Answer: C) Embryonic demise
53. What is the earliest structure visible in a developing embryo on ultrasound?
A) Fetal pole
B) Yolk sac
C) Amniotic sac
D) Placenta
Explanation:
The yolk sac is the first structure seen inside the gestational sac (by 5-6 weeks). The fetal pole follows at 5.5-6 weeks.
Answer: B) Yolk sac
54. A CRL measurement of 10 mm corresponds to which gestational age?
A) 5 weeks
B) 6 weeks
C) 7 weeks
D) 8 weeks
Explanation:
A CRL of ~10 mm corresponds to 7 weeks gestation. CRL is the most accurate measurement for dating pregnancy in the first trimester.
Answer: C) 7 weeks
55. A large nuchal translucency (NT) measurement in the first trimester is associated with:
A) Normal pregnancy
B) Fetal neural tube defects
C) Chromosomal abnormalities (e.g., Down syndrome)
D) Amniotic band syndrome
Explanation:
Increased NT (>3 mm) at 11-14 weeks suggests trisomies (e.g., Down syndrome), Turner syndrome, or congenital heart defects.
Answer: C) Chromosomal abnormalities (e.g., Down syndrome)
56. Which of the following is NOT a feature of anencephaly on ultrasound?
A) Absence of cranial bones
B) Frog-eye appearance
C) Increased amniotic fluid (polyhydramnios)
D) Presence of normal brain tissue
Explanation:
Anencephaly is a neural tube defect where the cranial vault and brain tissue are absent. It shows a "frog-eye" appearance and polyhydramnios due to impaired swallowing.
Answer: D) Presence of normal brain tissue
57. What is the most common congenital heart defect detected in the first trimester?
A) Tetralogy of Fallot
B) Hypoplastic left heart syndrome
C) Atrioventricular septal defect (AVSD)
D) Ventricular septal defect (VSD)
Explanation:
AVSD is the most common congenital heart defect seen in the first trimester and is strongly associated with Down syndrome (Trisomy 21).
Answer: C) Atrioventricular septal defect (AVSD)
58. What is the sonographic feature of a cystic hygroma in early pregnancy?
A) Small anechoic sac in the uterine cavity
B) Fluid-filled structure in the fetal neck
C) Thickened placenta with cysts
D) Enlarged kidneys with multiple cysts
Explanation:
A cystic hygroma appears as a fluid-filled, septated mass in the fetal neck, often linked to Turner syndrome and chromosomal abnormalities.
Answer: B) Fluid-filled structure in the fetal neck
59. What is the most common ultrasound finding in fetal acrania?
A) Absence of cranial bones with brain tissue present
B) Normal skull with small ventricles
C) Enlarged amniotic sac
D) Polyhydramnios with a small fetus
Explanation:
Acrania is a lethal neural tube defect where the skull bones fail to form, leaving exposed brain tissue. It often progresses to anencephaly.
Answer: A) Absence of cranial bones with brain tissue present
60. What is the best ultrasound marker for detecting spina bifida in early pregnancy?
A) Lemon sign
B) Clenched fists
C) Absent nasal bone
D) Single umbilical artery
Explanation:
The lemon sign (frontal skull flattening) is an early marker of spina bifida. Later in pregnancy, the banana sign (cerebellar compression) is also seen.
Answer: A) Lemon sign
61. What is a key ultrasound finding in gastroschisis?
A) Abdominal wall defect with free-floating bowel
B) Herniated liver into the umbilical cord
C) Thickened nuchal translucency
D) Enlarged fetal kidneys
Explanation:
Gastroschisis is a paraumbilical abdominal wall defect where the bowel herniates outside without a covering membrane.
Answer: A) Abdominal wall defect with free-floating bowel
62. What is the earliest gestational age at which holoprosencephaly can be detected?
A) 5 weeks
B) 6 weeks
C) 9-10 weeks
D) 14 weeks
Explanation:
Holoprosencephaly (failure of the forebrain to divide) can be detected by 9-10 weeks as an abnormally shaped head and absent midline structures.
Answer: C) 9-10 weeks
63. Which of the following ultrasound findings is associated with trisomy 18 (Edwards syndrome)?
A) Omphalocele
B) Clenched fists
C) Choroid plexus cysts
D) All of the above
Explanation:
Trisomy 18 (Edwards syndrome) shows multiple anomalies, including clenched fists, omphalocele, and choroid plexus cysts.
Answer: D) All of the above
64. What is the ultrasound feature of an omphalocele?
A) Herniation of bowel covered by a membrane
B) Free-floating intestines outside the abdomen
C) Cystic mass in the fetal neck
D) Enlarged bladder with hydronephrosis
Explanation:
Omphalocele is an abdominal wall defect where bowel and sometimes liver herniate into the umbilical cord and are covered by a membrane.
Answer: A) Herniation of bowel covered by a membrane
65. What is the best method to evaluate early skeletal anomalies on ultrasound?
A) Transvaginal ultrasound
B) Doppler imaging
C) 3D ultrasound
D) Amniocentesis
Explanation:
3D ultrasound provides detailed skeletal imaging and is particularly useful for detecting anomalies like dwarfism, limb deformities, and cranial defects.
Answer: C) 3D ultrasound
66. Which of the following is a characteristic ultrasound finding in Turner syndrome during the first trimester?
A) Increased nuchal translucency
B) Omphalocele
C) Polyhydramnios
D) Cystic hygroma
Explanation:
Turner syndrome (45,X) is commonly associated with the presence of a cystic hygroma during the first trimester. This appears as a fluid-filled, septated mass in the fetal neck region on ultrasound. While increased nuchal translucency can also be observed, the presence of a cystic hygroma is more characteristic of Turner syndrome.
Answer: D) Cystic hygroma
67. At what gestational age is the fetal stomach typically visible on ultrasound?
A) 5 weeks
B) 6 weeks
C) 8 weeks
D) 11 weeks
Explanation:
The fetal stomach becomes visible on ultrasound around 11 weeks of gestation as a fluid-filled structure in the upper abdomen. Its visualization is an important indicator of normal fetal development and swallowing.
Answer: D) 11 weeks
68. Which ultrasound finding is indicative of a molar pregnancy?
A) Double decidual sac sign
B) Snowstorm appearance
C) Yolk sac larger than 7 mm
D) Absent nasal bone
Explanation:
A molar pregnancy is characterized by a "snowstorm" appearance on ultrasound, representing a mass of cystic structures without a viable fetus. This appearance is due to the presence of numerous swollen chorionic villi.
Answer: B) Snowstorm appearance
69. What is the significance of an absent nasal bone on first-trimester ultrasound?
A) It is a normal variant with no clinical significance.
B) It indicates a high risk for trisomy 21 (Down syndrome).
C) It suggests neural tube defects.
D) It is associated with Turner syndrome.
Explanation:
An absent nasal bone on first-trimester ultrasound is a soft marker associated with an increased risk of trisomy 21 (Down syndrome). However, it is not diagnostic, and further testing, such as non-invasive prenatal testing (NIPT) or invasive diagnostic procedures, may be recommended.
Answer: B) It indicates a high risk for trisomy 21 (Down syndrome).
70. Which of the following conditions is associated with echogenic intracardiac focus (EIF) on ultrasound?
A) Trisomy 21 (Down syndrome)
B) Trisomy 18 (Edwards syndrome)
C) Turner syndrome
D) Patau syndrome
Explanation:
An echogenic intracardiac focus (EIF) is a small bright spot seen in the heart on ultrasound and is considered a soft marker for trisomy 21 (Down syndrome). While it can be seen in normal fetuses, its presence may warrant further evaluation for chromosomal abnormalities.
Answer: A) Trisomy 21 (Down syndrome)
71. What does an increased nuchal translucency measurement indicate in a first-trimester ultrasound?
A) Increased risk of chromosomal abnormalities
B) Neural tube defects
C) Congenital diaphragmatic hernia
D) Fetal anemia
Explanation:
Increased nuchal translucency (NT) measurement in the first trimester is associated with a higher risk of chromosomal abnormalities, such as trisomy 21, trisomy 18, and trisomy 13. It may also indicate other genetic syndromes and congenital heart defects.
Answer: A) Increased risk of chromosomal abnormalities
72. Which of the following ultrasound findings is most suggestive of trisomy 18 (Edwards syndrome)?
A) Single umbilical artery
B) Choroid plexus cysts
C) Clenched hands with overlapping fingers
D) Echogenic bowel
Explanation:
Clenched hands with overlapping fingers observed on ultrasound are characteristic findings associated with trisomy 18 (Edwards syndrome). This finding, along with other anomalies, aids in the prenatal diagnosis of this condition.
Answer: C) Clenched hands with overlapping fingers
73. What is the significance of a single umbilical artery (SUA) detected on ultrasound?
A) It is a normal variant with no associated risks.
B) It is associated with an increased risk of chromosomal abnormalities and congenital anomalies.
C) It indicates fetal anemia.
D) It suggests neural tube defects.
Answer: B) It is associated with an increased risk of chromosomal abnormalities and congenital anomalies.
Explanation:
A single umbilical artery (SUA) is
Explanation:
Ian Donald, a Scottish obstetrician, is known as the father of medical ultrasound. He was the first to introduce ultrasound in obstetrics in the 1950s. His pioneering work led to the development of ultrasound imaging for fetal assessment.
- John Campbell → Contributed to ultrasound research but not specifically in obstetrics.
- Jal Nelson & Bennett → No significant historical contributions in the introduction of obstetric ultrasound.
The correct answer is:
(a) Ian Donald
Explanation:
Guidelines for obstetric ultrasound imaging are provided by various national and international organizations, but AERB (Atomic Energy Regulatory Board) is not directly related to obstetric ultrasound.
- PCPNDT Act (Pre-Conception and Pre-Natal Diagnostic Techniques Act) → Governs the use of ultrasound to prevent female feticide in India.
- AIUM (American Institute of Ultrasound in Medicine) → Provides guidelines on safe and effective ultrasound use.
- ACOG (American College of Obstetricians and Gynecologists) → Issues guidelines for obstetric ultrasound practices.
- AERB (Atomic Energy Regulatory Board) → Regulates radiation safety for equipment like X-ray and CT, but not specific to ultrasound.
The correct answer is:
(d) AERB (Atomic Energy Regulatory Board)
Explanation:
A routine fetal ultrasound scan (such as a standard second-trimester anomaly scan) typically requires at least 20 minutes to thoroughly assess the fetal anatomy, amniotic fluid, placenta, and other structures.
- 10 minutes → Too short for a detailed evaluation.
- 20 minutes → Minimum recommended time for a complete scan.
- 30–40 minutes → May be needed for more detailed scans, high-risk pregnancies, or difficult fetal positions.
The correct answer is: (b) 20 min
77. The best time for fetal anomaly Scan is:
(c) 28 wks
Explanation:
The fetal anomaly scan (also called the mid-trimester or level 2 ultrasound) is best performed at 18 to 22 weeks, with 20 weeks being the ideal time. This scan is done to check the baby's anatomy, including the brain, heart, spine, kidneys, limbs, and other organs, to detect any congenital abnormalities.
- 12 weeks → Too early for detailed anatomical assessment.
- 20 weeks → Best time for detecting structural anomalies.
- 28 weeks → More useful for growth scans rather than anomaly detection.
- 36 weeks → Late pregnancy scan; mainly assesses fetal position and well-being.
The correct answer is:
(b) 20 weeks
78. The best time for fetal nuchal translucency Scan is:
Explanation:
The fetal nuchal translucency (NT) scan is best performed between 11 to 14 weeks of gestation. This ultrasound measures the fluid-filled space at the back of the fetal neck and is used to assess the risk of chromosomal abnormalities such as Down syndrome (Trisomy 21), Trisomy 18, and Trisomy 13.
- Before 11 weeks → The fetal structures are too small for accurate measurement.
- After 14 weeks → The nuchal translucency starts to reduce or may no longer be detectable.
The correct answer is:
(a) 11 to 14 weeks
79. 'Trouser' sign in
fetal ultrasound is for:
Explanation:
The "trouser sign" in fetal ultrasound refers to the bifurcation of the ascending aorta into the right and left coronary arteries, resembling the shape of trousers. This sign is typically seen in the LVOT (Left Ventricular Outflow Tract) view, which helps assess the aorta's origin from the left ventricle.
- RVOT view (Right Ventricular Outflow Tract) → Assesses the pulmonary artery.
- LVOT view (Left Ventricular Outflow Tract) → Evaluates the aorta and its origin.
- Four-chamber view → Assesses the atria and ventricles.
- Two-chamber view → Primarily evaluates the left atrium and ventricle.
The correct answer is:
(b) LVOT view (Left Ventricular Outflow Tract view)
80. Fetal Bradycardia means (Heart rate):
Explanation:
Fetal bradycardia is defined as a sustained fetal heart rate (FHR) below 110 bpm.
- Normal fetal heart rate → 110–160 bpm
- Mild bradycardia → 100–110 bpm
- Severe bradycardia → <100 bpm
The correct answer is:
(b) <100 bpm
81. Fetal tachycardia means (Heart rate):
Explanation:
Fetal tachycardia is defined as a sustained fetal heart rate (FHR) of more than 160 bpm. However, mild tachycardia is considered between 160–180 bpm, and severe tachycardia is >180 bpm.
- Normal fetal heart rate → 110–160 bpm
- Mild tachycardia → 160–180 bpm
- Severe tachycardia → >180 bpm
The correct answer is:
(d) >180 bpm
82. The standard fetal anatomic survey done in:
Explanation:
The standard fetal anatomic survey (also known as the mid-trimester or level 2 ultrasound) is typically performed during the second trimester, between 18 to 22 weeks of pregnancy.
- First trimester → Early scans focus on confirming pregnancy, viability, and nuchal translucency screening.
- Second trimester → This is the ideal time for a detailed fetal anatomy scan, assessing organs, limbs, spine, and detecting any congenital anomalies.
- Third trimester → Ultrasounds may still be done but are usually for growth monitoring rather than a full anatomic survey.
The correct answer is:
(b) Second trimester
83. Which of the following technique? is not an ultrasound imaging
- EBUS (Endobronchial Ultrasound) → Uses ultrasound for imaging inside the airways and lungs.
- 2D ECHO (Two-Dimensional Echocardiography) → Uses ultrasound to create images of the heart.
- HSG (Hysterosalpingography) → Uses X-rays and contrast dye to evaluate the uterus and fallopian tubes. (Not an ultrasound technique)
- EUS (Endoscopic Ultrasound) → Uses an endoscope with ultrasound to examine internal organs.
(b) HSG (Hysterosalpingography)
84. Which of the
following is an ultrasound technique?
Explanation:
-
Hystero sonography (also called saline infusion sonography) is an ultrasound technique used to examine the uterus and endometrial cavity. It involves injecting a sterile saline solution into the uterus while performing transvaginal ultrasound to get a clearer view of abnormalities such as polyps, fibroids, or adhesions.
-
Hystero salpingography (HSG) is an X-ray-based technique that uses contrast dye to evaluate the uterine cavity and fallopian tubes. It is not an ultrasound technique.
-
Hysteroscopy is a minimally invasive endoscopic procedure that involves inserting a hysteroscope (a thin, lighted tube) into the uterus to directly visualize the uterine cavity. It is not an ultrasound technique.
-
None is incorrect because hystero sonography is an ultrasound technique.
85. Which of the
following Imaging? is not correct in ultrasound
Explanation:
-
A-scan (Amplitude scan) → Correct
- One-dimensional ultrasound technique used primarily in ophthalmology to measure distances (e.g., axial length of the eye).
-
B-scan (Brightness scan) → Correct
- Two-dimensional ultrasound imaging used for diagnostic purposes in various medical fields, including obstetrics and internal organ imaging.
-
C-scan (Colour Doppler scan) → Incorrect
- There is no standard ultrasound imaging technique called "C-scan."
- Colour Doppler ultrasound is a technique used to assess blood flow but is not termed "C-scan."
-
M-scan (Motion scan) → Correct
- Also known as M-mode (Motion mode), it is used to display moving structures, such as heart valves and fetal cardiac activity.
86. Epidemiological studies found associations from fetal ultrasound except:
Explanation:
Epidemiological studies have explored potential associations between fetal ultrasound exposure and certain neurological and developmental outcomes. However, no conclusive evidence links fetal ultrasound to malignancy (cancer).
-
(a) Dyslexia → Possible association
- Some studies suggest a weak correlation between prenatal ultrasound exposure and dyslexia, though evidence is not strong or definitive.
-
(b) Delayed speech → Possible association
- Some research indicates a potential link between fetal ultrasound and delayed speech development, but findings remain inconclusive.
-
(c) Malignancy → No established association
- There is no scientific evidence supporting a connection between fetal ultrasound and cancer development.
-
(d) Left-handedness → Possible association
- Some studies suggest a slightly increased incidence of left-handedness in individuals exposed to fetal ultrasound, but the clinical significance is uncertain.
87. Uterine cavity implantation of embryo completed by:
Explanation:
- Implantation of the embryo into the uterine cavity typically occurs 6–10 days after ovulation (which occurs around day 14 of a standard 28-day menstrual cycle).
- By day 20, the blastocyst is fully embedded in the endometrium, marking the completion of implantation.
Breakdown of the implantation timeline:
- Day 14 → Ovulation occurs
- Day 15-16 → Fertilization happens in the fallopian tube
- Day 18-19 → The blastocyst reaches the uterus and begins implantation
- Day 20 → Implantation is completed
Why other options are incorrect?
- (a) 17th day → Too early; the fertilized egg is still traveling through the fallopian tube.
- (c) 23rd day → By this time, implantation is already complete, and the embryo is developing.
- (d) 26th day → The placenta is already forming, and early pregnancy hormonal changes are well underway.
Correct answer: (b) 20th day
88. What is the earliest evidence of intrauterine pregnancy on ultrasound?
(c) Yolk sac
Explanation:
The earliest evidence of an intrauterine pregnancy (IUP) on ultrasound is the intradecidual sign, which appears around 4 to 4.5 weeks of gestation on transvaginal ultrasound.
Why is the intradecidual sign the earliest?
- It represents the gestational sac implanting within the endometrium before the yolk sac or fetal pole becomes visible.
- It appears as a small fluid-filled sac within the thickened decidua.
- It is detectable before the double decidual sac sign (DDS) and is used to confirm an intrauterine pregnancy early.
Why are the other options incorrect?
- (b) Corpus luteal cyst → A corpus luteal cyst is a functional ovarian cyst that supports early pregnancy by producing progesterone, but it is not a definitive sign of an intrauterine pregnancy.
- (c) Yolk sac → The yolk sac appears slightly later (around 5 weeks gestation), making it a later sign than the intradecidual sign.
- (d) Cardiac activity → Fetal cardiac activity is visible by 6-7 weeks gestation, much later than the first signs of pregnancy.
Explanation:
The intradecidual sign is an early marker of intrauterine pregnancy and can be seen on transvaginal ultrasound at approximately 4 to 4.5 weeks of gestation, but it is most commonly identified by 5 weeks.
- It appears as a small fluid-filled gestational sac implanted within the thickened decidua.
- It helps differentiate early intrauterine pregnancy (IUP) from an ectopic pregnancy before the yolk sac or fetal pole becomes visible.
Why are the other options incorrect?
- (a) 3 weeks → Too early; the embryo is still traveling through the fallopian tube.
- (c) 7 weeks → By this time, the yolk sac and fetal pole with cardiac activity should already be visible.
- (d) 9 weeks → The fetus is well-developed, with visible limb buds and a strong heartbeat.
Correct answer: (b) 5 wk
90. The foetal cardiac activity ultrasound as early as: is detected on abdominal fetal sonography
Explanation:
Fetal cardiac activity can be detected at different times depending on whether a transvaginal ultrasound (TVUS) or an abdominal ultrasound is used:
-
Transvaginal ultrasound (TVUS):
- Detects fetal heart activity as early as 5.5 to 6 weeks gestation.
-
Abdominal ultrasound:
- Fetal cardiac activity is typically detected later, around 8 weeks due to lower resolution and the need for a larger fetal size.
Why are the other options incorrect?
- (a) 4 weeks → Too early; the embryo is just implanting, and no heartbeat is visible.
- (b) 6 weeks → Possible with transvaginal ultrasound, but not always with abdominal ultrasound.
- (d) 10 weeks → By this time, cardiac activity is almost always detected, but it can usually be seen earlier (by 8 weeks with an abdominal scan).
Correct answer: (c) 8 wk
Explanation:
The double decidual sac sign (DDSS) is an important ultrasound finding that helps confirm an early intrauterine pregnancy (IUP) and distinguish it from other conditions like a decidual cast in an ectopic pregnancy.
Here’s why each statement is correct:
-
(a) Differentiates between early intrauterine pregnancy and decidual cast of ectopic pregnancy
- DDSS is a reliable indicator of an early intrauterine pregnancy, helping to rule out a pseudo-gestational sac seen in ectopic pregnancy.
-
(b) Its sonographic visualization of three layers of decidua
- The three layers of the decidua involved are:
- Decidua basalis (deep layer where implantation occurs)
- Decidua capsularis (surrounds the gestational sac)
- Decidua parietalis (lines the rest of the endometrial cavity)
- The three layers of the decidua involved are:
-
(c) One ring is created by the gestational sac and the other by echogenic endometrium
- The two concentric echogenic rings seen on ultrasound are:
- The inner ring (formed by the gestational sac and decidua capsularis)
- The outer ring (formed by the echogenic endometrium and decidua parietalis)
- The two concentric echogenic rings seen on ultrasound are:
Correct answer: (d) All
Explanation:
The yolk sac is the first anatomical structure visible within the gestational sac in an intrauterine pregnancy. It plays a crucial role in early fetal development by providing nutrients and aiding in blood cell formation before the placenta takes over.
- The yolk sac can typically be seen on transvaginal ultrasound (TVUS) by 5 weeks of gestation.
- It is most prominent between 5 to 11 weeks of pregnancy.
- After 11 weeks, the yolk sac starts shrinking and eventually disappears as the placenta takes over its functions.
Why are the other options incorrect?
- (b) 3 to 7 weeks → Too early; the yolk sac is usually not visible before 5 weeks.
- (c) 9 to 15 weeks → The yolk sac starts regressing around 11 weeks, so it is not typically seen as late as 15 weeks.
- (d) 10 to 16 weeks → The yolk sac is almost always gone by 12 weeks.
Correct answer: (a) 5 to 11 weeks
Explanation:
The yolk sac is the first visible structure inside the gestational sac and plays an essential role in early fetal development. Its diameter is an important parameter in assessing pregnancy viability.
- The normal yolk sac diameter ranges between 2 to 6 mm.
- A yolk sac diameter greater than 6 mm is considered abnormal and may indicate an increased risk of miscarriage or fetal abnormalities.
Why are the other options incorrect?
- (a) 3 mm → Within the normal range, but not the upper limit.
- (c) 9 mm → Too large; a yolk sac this size is often associated with poor pregnancy outcomes.
- (d) 12 mm → Extremely abnormal; suggests a non-viable pregnancy.
Correct answer: (b) 6 mm
Explanation:
A small yolk sac is not strongly associated with pregnancy failure, unlike other abnormalities such as a large, calcified, or irregular yolk sac.
Poor Prognostic Signs for Pregnancy Failure:
- (a) Large yolk sac (Poor prognosis)
- A yolk sac diameter >6 mm is linked to a higher risk of pregnancy loss.
- (b) Calcified yolk sac (Poor prognosis)
- A calcified or echogenic yolk sac is a sign of embryonic demise or fetal demise.
- (d) Irregular yolk sac (Poor prognosis)
- An abnormally shaped, collapsed, or fragmented yolk sac is associated with pregnancy failure.
Why is (c) Small yolk sac not a poor prognostic sign?
- A small yolk sac (<2 mm) is less commonly associated with pregnancy loss compared to a large or irregular yolk sac.
- Some cases of small yolk sacs can still lead to normal pregnancies.
Correct answer: (c) Small yolk sac
Explanation:
The Double Bubble Sign in early pregnancy ultrasound refers to the appearance of two adjacent fluid-filled structures within the gestational sac:
- Amnion → The thin membrane surrounding the developing embryo.
- Yolk sac → A round structure that provides early nutrition to the embryo.
This sign is typically seen around 5.5 to 7 weeks of gestation on transvaginal ultrasound (TVUS). It confirms an early intrauterine pregnancy and the presence of a developing embryo.
Why are the other options incorrect?
- (b) Amnion & chorion → The chorion surrounds the entire gestational sac but does not contribute to the double bubble appearance.
- (c) Chorion & yolk sac → The chorion is the outer membrane, and it does not form a distinct "bubble" in early ultrasound.
- (d) Primary & secondary yolk sacs → Only the secondary yolk sac is typically visible in normal embryonic development. The primary yolk sac regresses and is not seen on ultrasound.
Correct answer: (a) Amnion & yolk sac
Explanation:
The amniotic membrane is initially seen as a thin, separate structure from the chorion in early pregnancy. However, as the pregnancy progresses, the amnion and chorion fuse.
- The amniotic membrane remains separately visible on ultrasound until around 16 weeks of gestation.
- By 16–17 weeks, the amnion and chorion fuse to form a single membrane, making the amnion no longer separately distinguishable.
Why are the other options incorrect?
- (a) 8 weeks → The amnion is still distinctly visible but too early for fusion.
- (b) 12 weeks → The amniotic membrane is still separate at this stage.
- (c) 14 weeks → Fusion may begin around this time, but it is not complete.
Correct answer: (d) 16 weeks
Explanation:
Umbilical cord cysts are fluid-filled structures within the umbilical cord and can be classified as true cysts (lined with epithelium) or pseudocysts (caused by localized edema).
- First-trimester umbilical cord cysts are generally benign and have no clinical significance if they are isolated and disappear by the second trimester.
- Second- and third-trimester cord cysts may be associated with fetal anomalies (e.g., chromosomal abnormalities, omphalocele, or urinary tract defects).
Why are the other options incorrect?
- (b) Second trimester→ Cord cysts persisting into the second trimester may indicate fetal anomalies and require further evaluation.
- (c) Third trimester→ Third-trimester cord cysts are uncommon and may suggest fetal pathology, including genetic disorders.
- (d) All trimesters → Cord cysts in later trimesters may have clinical significance, whereas first-trimester cysts are usually benign.
Correct answer: (a) First trimester
Explanation:
The normal fetal umbilical cord consists of:
- Two umbilical arteries → Carry deoxygenated blood from the fetus to the placenta.
- One umbilical vein → Carries oxygenated blood from the placenta to the fetus.
This 2 arteries & 1 vein (2A:1V) structure is essential for fetal circulation and is surrounded by Wharton's jelly, which protects the vessels from compression.
Why are the other options incorrect?
- (b) One artery & two veins → Incorrect; this is not the normal umbilical cord structure.
- (c) Two arteries & two veins → Incorrect; the umbilical cord normally has only one vein.
- (d) One artery & one vein → Single umbilical artery (SUA) is an abnormality associated with congenital anomalies.
Correct answer: (a) Two arteries & one vein
Explanation:
On transvaginal ultrasound (TVS), an embryo can be visualized within the gestational sac as early as 5 weeks of gestation.
Key developmental ultrasound milestones:
- 4 weeks → Gestational sac may be seen, but no embryo yet.
- 5 weeks → Embryo first becomes visible as a fetal pole inside the gestational sac.
- 5.5 to 6 weeks → Yolk sac and fetal cardiac activity can be detected.
- 6-7 weeks → Clear visualization of the embryo with heartbeat.
Why are the other options incorrect?
- (a) 4 weeks → Too early; only a gestational sac may be seen, but no embryo.
- (c) 6 weeks → The embryo is definitely visible by now, but it can already be seen at 5 weeks.
- (d) 7 weeks → The embryo is fully visible by 7 weeks, but it first appears earlier (at 5 weeks).
Correct answer: (b) 5 weeks
Explanation:
Early pregnancy failure (also called missed abortion or embryonic demise) can be diagnosed using specific ultrasound criteria. However, the correct cutoff for mean sac diameter (MSD) without an embryo varies depending on whether transvaginal (TVS) or transabdominal (TAS) ultrasound is used.
Key Ultrasound Criteria for Early Pregnancy Failure:
- Embryo without cardiac activity on TVS (Suggests pregnancy failure)
- Embryo without cardiac activity on TAS (Suggests pregnancy failure)
- MSD ≥ 25 mm without an embryo on TVS (Confirms pregnancy failure)
- MSD ≥ 25 mm without an embryo on TAS (Incorrect cutoff; TAS is less sensitive than TVS)
- MSD ≥ 20 mm without a yolk sac on TVS (Suggests pregnancy failure)
Why is (c) incorrect?
- The correct threshold for diagnosing pregnancy failure using TAS is an MSD of 25 mm without a yolk sac or an embryo.
- Since TAS is less sensitive than TVS, MSD criteria are more reliable on TVS than TAS.
- If MSD is ≥ 25 mm without an embryo on TVS, it confirms pregnancy failure, but not necessarily on TAS.
Why are the other options correct?
- (a) Identify an embryo without cardiac activity on TVS → A non-viable embryo can be confirmed on TVS if there is no heartbeat.
- (b) Identify an embryo without cardiac activity on TAS → A non-viable embryo can also be seen on TAS, though it is less sensitive.
- (d) MSD of 20 mm without a yolk sac on TAS → Suggests a non-viable pregnancy, though TVS is preferred for confirmation.
Correct answer: (c) MSD of 25 mm without an embryo on TAS
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