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 > or = 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 <3 mm in seven cases (17%); no hydrops was present and only one had an abnormal karyotype (47 + 18). Eight babies with CH without aneuploidy or hydrops were born alive, seven among them were without malformations and are developing normally at 1 to 18 months of age, the remaining one presented with CHARGE syndrome.

Conclusions: CH is an independent entity from NT and its association with increased NT carries a poor prognosis.