Understanding Two-Vessel Umbilical Cords: Causes, Risks & Implications

Question
What is the seriusness in having a 2 vesel cord instead of a 3 vesel cord?

Answer
A two vessel cord is the absence oof one umbilical aretery. This occurs about once in 500 deliveries and 6% of twin gestations.  The cause may be aplasia or atrophy of the missing vessel. The anomaly is more common in blacks than whites but equally frequent in primiparas and multiparas. About 30% of these infants will have structural defects. There is also a strong association between fetal structural anomalies and placental vascular occlusion or thrombosis. If we know about the cords early in the pregnancy, perinatal evaluation should be done. Usually we find out about it at delivery, and in the last 25 years in practice, I have not seen any untoward effects or structural abnormalities in any of the cases where I have noticed a 2 vessel cord. I would not worry about it. Certainly, a pediatric exam after delivery will show any structural anomalies.