Karyotype and outcome of fetuses diagnosed with cystic hygroma in the first trimester in relation to nuchal translucency thickness

Objectives To determine the incidence and to examine the karyotype and the outcome of fetuses diagnosed with cystic hygroma (CH) at 11–14 weeks of gestation. Methods The presence of bilateral cystic anechoic cavities in the neck, nuchal translucency (NT), malformations and hydrops was prospectively recorded in 6894 ultrasound examinations in the first trimester, between 2001 and 2004. Results Forty‐two fetuses (0.62%) were diagnosed with CH in the first trimester of pregnancy and 60% of these had an abnormal karyotype. NT was ≥3 mm in 83% and hydrops was present in 40% of the cases. The karyotype was abnormal in 25 (69%) of these, showing trisomy 18 and 45,XO more often than trisomy 21. NT was