Spontaneous resolution of neonatal umbilical vein thrombosis in the absence of anticoagulant therapy: a case report

BACKGROUND: Umbilical vein thrombosis (UVT) is an uncommon but potentially serious neonatal condition. While most cases are associated with risk factors such as catheterization or congenital anomalies, spontaneous resolution without anticoagulation remains rare. CASE PRESENTATION: A full-term Chinese female neonate, small for gestational age (birth weight 2670 g, < 10th percentile), was delivered via emergency cesarean section at 39 weeks and 1 day because of placental abruption and chorioamnionitis. The newborn presented with poor respiratory effort and cyanosis, with Apgar scores of 6, 10, and 10 at 1, 5, and 10 min, respectively. Initial postnatal ultrasonography revealed a moderately echogenic lesion in the intrahepatic umbilical vein, which was consistent with the results of UVT. The infant required initial respiratory support, empirical antibiotics, and myocardial protection therapy. Laboratory tests revealed mild metabolic acidosis, electrolyte imbalance, and elevated white blood cell count and elevated myocardial enzymes, with no evidence of coagulopathy or hereditary thrombophilia. During the first week, the patient's clinical status improved steadily with supportive care. Follow-up ultrasonography on day 5 confirmed a stable thrombus with no progression. By the 1-month follow-up, ultrasonography demonstrated complete thrombus resolution and obliteration of the umbilical vein lumen without residual blood flow. No anticoagulant therapy or surgical intervention was administered. The patient was discharged in good condition without complications. CONCLUSION: This case highlights the potential for spontaneous resolution of neonatal UVT under conservative treatment without the need for anticoagulation. Although UVT is rare and lacks standardized treatment guidelines, early detection via ultrasonography enables timely monitoring and intervention, reducing the risk of complications. In this case, perinatal risk factors such as placental abruption, chorioamnionitis, and neonatal asphyxia may have contributed to thrombus formation. Further studies are needed to explore the role of perinatal inflammatory conditions in neonatal thrombosis and to establish evidence-based management strategies.