Vascular Anomalies of the Umbilical Cord
· Single umbilical artery- SUA has a 0.2-1.0% incidence; 14-62% cases have other fetal malformations. A SUA is diagnosed on ultrasound when two vessels instead of the normal three are seen in the umbilical cord. Confusion may occur when one umbilical artery is severely hypoplastic.Sonographically SUA may be as large as the umbilical vein.
· Multivessel umbilical cord-This may be an antenatal indication of conjoined twinning.
· Umbilical vein varix-these normally have no sequelae.
· Giant dilatation of the umbilical vein- This has been reported as causing a cystic fetal abdominal mass. The cyst showed slow moving particles within it, presumably due to turbulent blood flow and clot. Doppler/color evaluation shows flow.
· Umbilical cord hemangioma- This may present as an umbilical cord mass. Doppler may be useful in diagnosis.
· Umbilical cord knot, umbilical cord prolapsed or nuchal cord- These are fetal life threatening situations.
· Persistent right umbilical vein- This is rare finding with 13 or so cases reported. The anomaly is usually associated with lethal malformation. Two cases have been reported with no associated abnormalities.
NB- Color flow mapping and duplex Doppler are useful adjuncts to diagnosis in all the above conditions.