PRENATAL-DIAGNOSIS OF TRISOMY-21 IN MONOZYGOTIC TWINS WITH INCREASED NUCHAL TRANSLUCENCY AND ABNORMAL SERUM BIOCHEMISTRY

We present a case of a monozygotic twin pregnancy who underwent routin e screening for chromosomal abnormalities at 14 weeks of gestation by ultrasonographic measurement of nuchal translucency and biochemical an alysis of maternal serum alpha fetoprotein and free beta human chorion ic gonadotrophin levels. Both screening methods indicated the pregnanc y to be at increased risk of Down syndrome, with the ultrasound findin gs suggesting both fetuses to be affected, An amniocentesis was perfor med, and karyotype analysis revealed trisomy 21 in both fetuses; the m other subsequently opted for a termination of pregnancy, This case ill ustrates that screening for trisomy 21 in twin pregnancies is possible by both nuchal translucency measurement and maternal serum markers.