Hi mam Only nuchal translucency is not confirmative of downs syndrome it may suggest a possibility For confirmation you need to do amniocentasis meaning ultrasound guided amniotic fluid aspiration and sent for karyotyping of cells If this is normal it rules out downs Done around 15-16 weeks of pregnancy For ruling out cardiac anomalies you can do fetal echo at or after 18-20 weeks

U can get triple test done by ur obstretician...repeat scan may help...need evaluation.