Best sonological marker for diagnosis of downs in 1st trimester:

Ans-A Ref: Dutta's Text Book of Obstetrics, 7th edition, pg 106. Williams Obstetrics, 23rd edition. Explanation: Antenatal Screening for Down's syndrome First-trimester screening for down's syndrome includes NT (nuchal translucency), PAPP-A, hCG Nuchal translucency > 3.5 mm is significant. It is done at 11-14 weeks Detection rate- 79-87% Triple test and quadruple tests are done in second trimesier at 15-20 weeks Triple test: hCG, AFP, unconjugated estriol. Quadruple test: triple test + inhibit! Integrated test: first trimester screening + quadruple test MSAFP|, UE3|, HCG|, Inhibin A| in down's syndrome. USG markers of Down's syndrome fetus (soft tissue markers) Nuchal fold thickening Mild renal pelvis dilatation Echogenic intracardiac focus Echogenic bowel Short femur Short humerus DOWN's syndrome around 40% congenital heart disease -Complete atrioventricular septal defect (CAVSD) - 37 percent -Ventricular septal defect (VSD) - 31 percent -ASD - 15 percent -Partial atrioventricular septal defect (PAVSD) - 6 percent -Tetralogy of Fallot (TOF) - 5 percent -PDA - 4 percent -Miscellaneous - 2 percent Reference: Uptodate; largest population based study on Downs done from UK