Population‐based study of the outcome following the prenatal diagnosis of cystic hygroma

Objective To identify the population prevalence, pregnancy outcome, and the pattern of associated anomalies with a prenatal diagnosis of cystic hygroma. Design We analysed the pregnancy outcomes from 99 cases of prenatally diagnosed cystic hygroma reported to the Trent Congenital Anomalies Register from 1 January 1997 to 31 December 1999, by means of an outcome reporting form completed by the notifying centre. Results We identified a population prevalence of 1 in 1775 livebirths for prenatally diagnosed cystic hygroma. There were 64 terminations of pregnancy, 19 spontaneous pregnancy failures, and 16 livebirths. Of the 87 pregnancies karyotyped, 53 (61%) demonstrated aneuploidy with Turner syndrome being the most common, 29 (33%). There were a large variety of structural malformations identified, however, only 14 out of 83 terminations of pregnancy and spontaneous pregnancy failures had post-mortem examinations. Termination of pregnancy for Turner syndrome not complicated by identified structural malformations was the norm. Of the 16 livebirths, only 6 were normal at birth, 1 other has had successful hygroma surgery. Four of the liveborn infants have since died. Conclusions The ‘normal outcome’ rate from pregnancies complicated by prenatally diagnosed cystic hygroma is less than 10% in this study (6/99). Prenatal diagnosis of cystic hygroma requires careful assessment of the fetus, with regard to both karyotyping and ultrasound. Post-mortem examination should be encouraged after termination of pregnancy, or spontaneous pregnancy loss. This is important not just to the current pregnancy but also for future pregnancies. Copyright © 2005 John Wiley & Sons, Ltd.