Umbilical cord cysts in early pregnancy

OBJECTIVE: To assess the prevalence, morphologic characteristics, and natural history of umbilical cord cysts detected by ultrasound in the first trimester of pregnancy. METHODS: This was an ultrasound screening study for the presence of umbilical cord cysts in 859 pregnant women with singleton live fetuses at 7-13 weeks' gestation. In all cases of cord cysts the scan was repeated fortnightly until the cyst resolved or a fetal abnormality was detected. All patients with ongoing pregnancies had detailed scans at 20 weeks. Infants and umbilical cords were examined after delivery for the presence of structural abnormalities. RESULTS: Umbilical cord cysts were present in 29 (3.4%) of the 859 pregnancies. Fetal abnormalities were found in seven (26%) of the 27 cases with ongoing pregnancies. The fetus was more likely to be abnormal if the cyst was located near the placental or fetal extremity of the cord (relative risk [RR] 3.3; 95% confidence interval [CI] 1.3, 8.5) or paraxially (RR 3.8; 95% CI 1.2, 12.0) or if it persisted beyond 12 weeks' gestation (RR 7.7; 95% CI 3.2, 18.6). CONCLUSIONS: The prevalence of umbilical cord cysts at 7-13 weeks' gestation is approximately 3%, and in more than 20% of cases there are fetal chromosomal or structural defects.