First trimester USG finding in Down syndrome-
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.
Nuchal thickening
Nuchal translucency
Cardiac anomalies
GI anomalies
Genetics of Common Disorders