Single umbilical artery

• Two vessel cord
• One umbilical artery and one umbilical vein
• In isolation, no adverse clinical outcome
• When accompanied by other anomalies, 50% chance for trisomy 13 and 18
• IUGR in 15% cases

Imaging

• Free loop of cord with 2 vessels
• 70% absent left umbilical artery
• Single umbilical artery is larger in size than 3 vessel umbilical artery, the single umbilical artery is >50% of diameter of umbilical vein
• Important to search for other anomlies – renal, cardiac, rule out trisomy 13 and 18