The umbilical vessels have two arteries and one vein, and thrombosis rarely occursin the umbilical vein and arteries. Umbilical artery thrombosis (UAT) has a low incidence ratecompared with umbilical venous thrombosis. Discordant umbilical arteries (DUAs), wherein thesize of the arteries is different, has rarely been reported, and the smaller umbilical artery has alsobeen described as the hypoplastic umbilical artery (HUA). UAT and HUA/DUAs can be relatedto poor perinatal outcomes or fetus malformation. We herein present a case of a nulliparous andprimigravid 37-year-old Japanese pregnant woman, with sonographic diagnosis of single umbilicalartery at 24 weeks of gestation by the loss of left-sided umbilical artery. Subsequently, serologicaltest showed elevated serum immunoglobulin M (IgM) and IgG antibodies for cytomegalovirus(CMV). Neither morphological nor growth abnormality of the fetus was sonographically found,and no CMV DNA was detected in the vaginal discharge. Clinical follow-up was performed, andthe fetus was small for gestational age during the course of the observation. At 40 and 5/7 weeksof gestation, vaginal delivery was attempted, but cesarean delivery was performed because fetaldistress was suspected by cardiotocography. An appropriate-for-age female neonate withoutanomaly was born, and the Apgar score was 8 and 9 after 1 and 5 min, respectively. Neitherelevated serum anti-CMV IgM antibodies nor presence of CMV DNA in the urine was found inthe neonate. Six days after cesarean section, the mother and neonate were discharged withoutany problems. A thin and hypercoiled umbilical cord was found macroscopically, and pathologyconfirmed that the umbilical cord had one vein and two arteries, which included an HUA showingocclusive thrombosis. The placenta showed no apparent abnormalities except for a small infarctionat the marginal zone. CMV infection was not found in the umbilical cord and placenta. Thepathogenesis of UAT was speculated to be related to the hypercoiled umbilical cord. This is thefirst case of a healthy, appropriate-for-age, full-term neonate born with UAT.
