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Dr.Niraj Mahajan
Dr.Niraj Mahajan
Dr.Niraj Mahajan


Ultrasound during Pregnancy

By AdminPosted On 05-Oct-2016

1. Expected fetal weight

In Ultrasound during Pregnancy, which of the following measurement is most reliable for expected fetal weight (EFW)?

a) Biperital diameter (BPD)
b) Abdominal circumference (AC)
c) Femur length (FL)
d) Length of radius
e) Head circumference (HC)
Correct Answer: b) Abdominal circumference. AC is not useful for dating but it is most useful in determining fetal weight in ultrasound during pregnancy. Combined with the BPD, with or without the fetal femur length, reliable formulas can be used to predict fetal weight.

2. Gestational Age - Dating Scan

Best indicator of gestational age on a Ultrasound during Pregnancy in the first trimester
a) Biparietal diameter
b) Crown rump length
c) Femur length
d) Gestational sac diameter
e) Head circumference
Correct Answer: b) Crown rump length. Biparietal diameter is appropriate after 14 weeks. Gestational sac measurements help in early pregnancy diagnosis in ultrasound during pregnancy.

3. Cardiac Activity

The cardiac activity can be seen first using transvaginal ultrasound during Pregnancy by how many weeks?
a) 5-6 weeks
b) 6-7 weeks
c) 7-8 weeks
d) 8-9 weeks
e) 9-10 weeks
Correct Answer: a) 5-6 weeks. By about 4.5 week, a small 2-3 mm gestational sac, which represents the chorionic cavity, can be visualized by transvaginal ultrasound during pregnancy (TVS). This is the first reliable sonographic evidence of pregnancy. Visualization of the yolk sac/embryo complex is diagnostic of an intrauterine pregnancy and excludes blighted ovum. The yolk sac should always be seen with TVS when the gestational sac reaches a mean diameter of 8 mm at 5 to 6 week. With TVS, embryos as small as 1 to 2 mm may be identified at similar stage of pregnancy. Although embryonic cardiac activity may be demonstrable in some pregnancies as early as 35 days after onset of last menstrual period, or in embryos as small as 1 mm, the absence of cardiac activity at such early stage could be normal.

4. Enlarged of Cisterna Magna

What is the clinical significance of isolated enlargement of Cisterna magna (>10 mm) in third trimester of pregnancy?
a) Dandy-Walker malformation
b) Trisomy 13
c) Trisomy 18
d) Turner syndrome
e) Other Aneuploidy
f) No clinical significance
Correct Answer: f) No clinical significance. Isolated enlargement of the cisterna magna to more than 10 mm is associated with normal pregnancy and neonatal outcome. Enlargement of the cisterna magna has been reported to be associated with aneuploidy. In studies of cisterna magna enlargement, however, those fetuses with abnormal chromosomes have had other sonographic abnormalities in addition to a large cisterna magna.But definitely we need to search for other abnormalities if it is enlarged in third trimester.

5. SEX chromosome disorder

All of the following conditions are SEX chromosome disorder EXCEPT
a) Turner syndrome
b) Klinefelter’s syndrome
c) Super female (47,XXX)
d) Down’s syndrome
e) XX gonadal dysgenesis
Correct Answer: d) Down’s syndrome. Sex chromosome disorders belong to a group of genetic conditions that are caused or affected by the loss or damage of sex chromosomes. Down’s syndrome (trisomy 21), is caused by the presence of all or part of a third copy of chromosome 21.

6. Congenital anomaly scan in first trimester

Which of the following congenital malformations can be diagnosed in the first trimester ?
a) Microcephaly
b) Anencephaly
c) Meningocele
d) Encephalocele
e) Omphalocele
Correct Answer: b) Anencephaly was the first fetal malformation to be diagnosed prenatally with the use of sonography. Exencephaly is characterized by a large amount of protruding, abnormally developed cerebral tissue. In both anencephaly and exencephaly, acrania is a constant finding. Rest all are diagnosed in second trimester.

7. Stomach Bubble

Visualisation of the "stomach bubble" on ultrasound is a significant sonographic observation after 14 weeks of gestation. What is responsible for the production of bubble in stomach?
a) Clostridium perfringens
b) E. coli
c) Clostridium difficile
d) Enterococcus faecalis
e) Other
Correct Answer: e) Other. Stomach or gastric bubble is normally seen in all fetuses beyond 14 weeks of gestation. It is not filled with gas. It is amnionitc fluid which is swallowed by fetus. The prenataly esophageal atresia can be diagnosed by absent fetal stomach bubble. In Tracheo-esophageal fistula it may or may not be seen. Fetus grows in sterile environment so there is no question of any micro-organism growing in fetus.

8. Prune belly syndrome

Prune belly syndrome can be diagnosed via ultrasound anomaly scan while a child is still in-utero. Which of the following organ/s can show abnormality on USG?
a) Liver
b) Kidney
c) Bladder
d) Lung
e) Heart
Correct Answer: b and c. An abnormally large abdominal cavity resembling that of an obese person is the key indicator, as the abdomen swells with the pressure of accumulated urine. Hydronephrosis from accumulation and backflow of urine from the bladder to the ureters and the kidneys. Prune belly syndrome is a rare, genetic birth defect of the urinary system. Partial or complete lack of abdominal muscles. If you are to select only one option then it would be bladder.

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Dr. Niraj Mahajan

MD- Gynecologist, Laparoscopic Surgeon, Uro-gynecologist , Infertility specialist & Cosmetic Gynecologist.

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