we are presenting a newborn baby born with an isolated single umbilical artery ( sua ) . second trimester ultrasound done at 27 weeks showed a sua and there were no other associated anomalies in the fetus as well as in the placenta . this was a preterm female baby with a birth weight of 2.2 kg . on examination , the baby was normal , and there were no dysmorphic features or obvious congenital anomalies . cut section - umbilical cord of the baby two vessel cord of the baby - macroscopic and microscopic view prenatal ultrasound evaluation for sua should be done during the second and third trimester of pregnancy . in this case , the second trimester ultrasound which was done at 27 weeks showed a sua with no other associated anomalies . there is also an increased risk of intrauterine growth restriction , prematurity and mortality among neonates with sua when compared with those with a three - vessel cord . the most common congenital anomalies associated with sua are renal , followed by cardiovascular and musculoskeletal . a significant proportion of infants with isolated sua may have occult renal malformations like vesico - ureteric reflux ( vur ) grade 2 or more . hence , these infants need to be followed up regularly , and we need to maintain a low threshold for diagnosing and managing urinary tract infections ( utis ) . once the uti is treated a micturating cystourethrogram needs to be done to rule out vur .
the umbilical cord usually contains two arteries and one vein . 
 the vein carries the oxygenated blood from the placenta to the fetus . 
 the arteries carry the deoxygenated blood and the waste products from the fetus to the placenta . 
 occasionally , primary agenesis or secondary atrophy of one of the arteries occurs resulting in single umbilical artery .