BACKGROUND: Bartter syndrome (BS) is a rare autosomal recessive renal disease. There are relatively few reports on fetal Bartter syndrome, but it has been documented that the condition can increase the incidence of prematurity and hypovolemia. Umbilical vein thrombosis (UVT) is a rare obstetric complication that poses a serious threat to fetal safety, potentially leading to acute fetal distress and even intrauterine fetal death. Consequently, early identification and intervention of UVT are crucial.

CASE PRESENTATION: We present a case of an emergency cesarean section prompted by ultrasound findings of intrahepatic segment of umbilical vein thrombosis and polyhydramnios. After birth, the newborn was admitted to the Department of Neonatology for observation and further treatment due to persistent, uncorrected hypokalemia. Genetic testing diagnosed the infant with Bartter syndrome type 4b. We hypothesize that the umbilical vein thrombosis and polyhydramnios in this case may be associated with fetal Bartter syndrome.

CONCLUSION: This case highlights a suspected instance of umbilical vein thrombosis and polyhydramnios potentially linked to fetal Bartter syndrome. Currently, the causes of umbilical vein thrombosis primarily focus on abnormalities in umbilical cord structure or mechanical injury to the cord, with few cases involving fetal genetic conditions. The purpose of this report is to enhance medical professionals' understanding of Bartter syndrome and to consider it as a possible cause of fetal umbilical vein thrombosis and polyhydramnios. Further research should explore the link between fetal Bartter syndrome, umbilical vein thrombosis, and polyhydramnios. Additionally, strengthening case collection and analysis will help accumulate experience, optimize management strategies, and improve maternal and fetal outcomes.