First trimester diagnosis of cystic hygromata using transvaginal ultrasound and cytogenetic evaluation.

We studied the outcome of fetuses in whom cystic hygroma was diagnosed in the first and early second-trimester of pregnancy using transvaginal ultrasonography. The purpose of this study was to evaluate the association between fetal cystic hygroma and fetal cytogenetic abnormalities, and the long-term prognosis. Thirty-five consecutive fetuses between 9.1 and 13.4 weeks of gestation diagnosed as having a nuchal hygroma were evaluated ultrasonographically and karyotyped. Those with a normal chromosome complement were ultrasonographically monitored throughout the remainder of the pregnancy to document the resolution of the hygroma. Eighteen of thirty-five fetuses were found to have a normal karyotype and five of these were aborted electively. The hygromas resolved in ten of these karyotypically normal fetuses within four weeks of initial diagnosis and they were phenotypically normal at birth. Seventeen fetuses were karyotypically abnormal with trisomy twenty-one being the most common abnormality. Prenatal cytogenetic analysis should be offered to women with fetal cystic hygroma diagnosed in the first trimester. A normal outcome is likely in those without chromosome abnormalities.