Umbilical artery thrombosis is a rare but clinically important finding: a series of 7 cases with clinical outcomes.

Umbilical artery thrombosis is a rare occurrence and is associated with poor neonatal outcomes. We present a series of 7 cases occurring over a 13-year period. The National Maternity Hospital is a tertiary referral center with approximately 10,000 births per annum. Cases were identified by a keyword search on the laboratory computer system. Seven cases were retrieved over a 13-year period (from an estimated 116,000 births): 5 cases from 7306 placentas and 2 cases from 1174 autopsies performed. Only cases with isolated umbilical artery thrombosis were included in the study. Placental histology from all cases was examined, placental gross findings were recorded, and clinical information and Doppler findings were obtained. Two infants were stillborn, and an additional 3 of the 7 cases were small for dates. All liveborn infants had a complicated neonatal course: 1 infant had a caudate infarction, 1 was born with partial acrania and schizencephaly, and 1 had a prolonged intensive care unit admission for low birth weight and jaundice. One case had absent end diastolic flow on Doppler ultrasound. Three cases had a cord diameter narrower than that expected for gestational age. All cases showed evidence of placental hypoperfusion. Umbilical artery thrombosis is a rare occurrence and carries a poor prognosis.