Objective To determine the outcome of all antenatally suspected cystic hygroma (CH) cases referred to the fetal medicine unit over a 11-year period in Wales.

Methodology A retrospective study of all pregnant women with suspected CH referred to the fetal medicine unit. Data were obtained from the Fetal Medicine, Cytogenetic and Fetal Morphology database. Neonatal outcomes for the survivors were obtained from the neonatal notes.

Results Out of 223 suspected cases referred there were 185 confirmed cases of CH between 1995 and 2006. 70% were diagnosed in the first trimester.

94 cases (50.8%) had an abnormal karyotype, nine of these were diagnosed at postmortem. The most common abnormal karyotype were 45X (40%), T21 (32%), T18 (17%), T13 (6%) and others (5%). The CMV IgM was positive in 2% of cases.

65 patients had a normal karyotype of which 43 (66%) continued their pregnancy. There were five intrauterine deaths and 17 underwent terminations.

The associated spontaneous spontaneous abortion rate was 14%. Associated cardiac defects were found in 9% of cases.

The authors could only trace the outcome of 29 live births of whom, only two had postnatal sequelae of CH. The other patients had returned to their original source hospitals and were not followed up.

Conclusion The study shows a 50% incidence of chromosomal abnormalities and a high spontaneous abortion and cardiac anomaly rate. It reveals that the prognosis is good for pregnancies complicated with CH with a normal karyotype and a normal anomaly scan.