<prompt> What is the commonest aneuploidy seen in neonates born with single umbilical aery?Trisomy 18Trisomy 13Trisomy 21Trisomy 15  <response>: Single umbilical aery: - It is seen in 5-101,000 bihs its frequency increases in twin bihs - 30 of these infants are associated with more than one congenital abnormalities; among which Trisomy 18 is most commonest - Though it is associated with increased risk for occult renal anomaly, if no other anomalies are present, need for renal USG is controversial 