An antenatal ultrasound done at 18-20 weeks of gestation is to detect:
Correct Answer: Fetal anomalies
Description: Ans: A (Fetal anomalies) Ref: DC Dutta's Textbook of Obstetricsf pg: 98Explanation:Advantages of 18- 20 weeks scan during pregnancyDetailed fetal anatomy survey to detect any structural anomalies.Placental localization.USG examination is performed as a routine at 18-20 weeks to rule out fetal anomalies.o Open spina bifida and Arnold Chiari malformationBanana sign - flattening of cerebellar hemispheres.Lemon sign- scalloping of frontal bones,o Anencephaly - frog's eye appearance (absence of calvarium).Stomach bubble seen normally by 20 weeks. Absent stomach bubbie-esophageal atresia.Gastroschisiso Paraumbilical defect.o Not covered by membrane - herniated smalt bowel loops floating free in ammotie fluid..o Not associated with chromosomal anomalies, prognosis is good..Omphaloceleo Midline defect, cord inserted on the herniated mass,o Covered by membrane-hernia contains intestines, liver or both,o 40-60% associated with chromosomal anomalies, prognosis is poor.Advantages of First Trimester Scan During PregnancyDetects early pregnancyo An intrauterine gestational sac should be seen by:TVS when maternal serum Beta hCG level is 1000-1200 mlU/ml.TAS when maternal serum Beta hCG level is 6000 mlUJml.Confirms intrauterine pregnancy - to rule out Ectopic and Molar pregnancy.o Ectopic pregnancy features in USG - pseudo gestational sac sign, echogenic fluid in POD, ring of fire {Echogenic ring) in Doppler.o Molar pregnancy in USG - snow storm appearance.Confirms viability of fetus - cardiac activity should appear by 7 weeks in TAS and 6 weeks in TVS.Accurate dating - USG is the best method to estimate gestational ageo CRL (crown rump length) is the most accurate parameter in first trimester,o Accuracy in estimating GA iso +/- 1 week in 1st: trimestero +/- 2 weeks in 2nd trimestero +/- 3 weeks in 3rd trimesterNumber of fetuses.Identifies any uterine or adnexal pathology.Fetal nuchal fold thickness of > 3 mm by USG is a strong marker for chromosomal anomalies in 1S1 trimester between 11-13 weeks.Advantages of 3rd Trimester Scan During PregnancyEstimated fetal weight - by measuring FL, BPD. HC. AC.Fetal growth profile - Abdominal circumference {AC) is die single most important parameter for assessment of fetal growth.
Category:
Gynaecology & Obstetrics
Get More
Subject Mock Tests
Practice with over 200,000 questions from various medical subjects and improve your knowledge.
Attempt a mock test nowMock Exam
Take an exam with 100 random questions selected from all subjects to test your knowledge.
Coming SoonGet More
Subject Mock Tests
Try practicing mock tests with over 200,000 questions from various medical subjects.
Attempt a mock test now