First trimester USG finding in Down syndrome-
Nuchal thickening
Nuchal translucency
Cardiac anomalies
GI anomalies
Ans. is 'b' i.e., Nuchal translucency Maternal serum screeningo 1st trimesterMaternal beta hCGo Higher than chromosomal ly normal fetuseso Difference increases with gestationPAPP-Ao Lower than chromosomally normal fetuseso Difference decreases with gestation: therefore not commonly used as a second-trimester testo 2nd trimesterTriple screeningMaternal free beta hCG: higher than chromosomally normal fetusesAFP: lower than chromosomally normal fetusesUnconjugated oestriol (uE3): lower than chromosomally normal fetusesUltrasoundo First trimesterNuchal translucency: thickness depends on the size of the fetus (CRL), but in general it is considered abnormal if >3 mm.There is recent evidence thai the inclusion of nasal bone measurement improves the specificity of 1st trimester datao Second trimesterApproximately 30% of babies with Down syndrome have detectable abnormalities on the mid-trimester ultrasound 1.
Genetics of Common Disorders