Predicting fetal karyotype in fetuses with omphalocele: The current role of ultrasound

OBJECTIVE: To assess the ability of ultrasound in predicting abnormal karyotype in pregnancies with prenatally diagnosed omphaloceles and to compare its test characteristics to previously published studies. METHODS: A retrospective case-control study of omphaloceles diagnosed at one center was performed from 1995-2007. Cases were those with an abnormal karyotype and controls were those with a normal karyotype. Data collection included demographics, karyotype results, and ultrasound findings. The number and type of associated anomalies were compared between the cases and controls. The sensitivity, specificity, positive predictive value, and negative predictive value for predicting an abnormal karyotype were calculated from previously published studies. RESULTS: Of the 73 subjects, there were 12 cases and 61 controls. The majority of women were Caucasian and primigravida. The cases were less likely to have an isolated omphalocele [1 (8.3%) vs. 27 (42.6%), OR = 0.122; 95% CI: 0.02-0.08] but were more likely to have two or more major anomalies [8 (66.7%) vs. 17 (27.9%), OR = 5.18; 95% CI: 1.19-24.04)] compared to the controls. Cardiac anomalies and only one additional major anomaly were not different between the two groups, P > 0.05. The test characteristics for this study were similar to previously published studies. CONCLUSIONS: Isolated omphaloceles were more likely to have a normal karyotype; however fetuses with multiple anomalies were more likely to have an abnormal karyotype. Despite advances in ultrasound technology, its ability for predicting an abnormal karyotype in these fetuses has not improved.