Background: Thrombosis of umbilical vessels is a rare but life-threatening pregnancy complication. The correct diagnosis and clinical management of umbilical cord thrombosis remain a challenge. This study aimed to evaluate the meaningful clinical manifestations and features of umbilical cord thrombosis and its optimal management options.Methods: This retrospective study analyzed umbilical cord thrombosis cases enrolled from January 1, 2011, to May 31, 2021. Data were collected from medical

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... ves where the diagnoses of all patients were established by histopathology.Results: A total of 66 patients with umbilical cord thrombosis were enrolled, including 20 patients with intrauterine fetal death and 6 with fatal labor induction in the second trimester. The overall incidence of umbilical cord thrombosis was 0.05% (66/123,746), and the incidence increased significantly in the last 2 years, reaching 0.19% in 2021. The chief complaint was decreased fetal movement (25/60) or nonreactive nonstress test (NST) (19/40). In the 20 patients with intrauterine stillbirth, 8 patients had ignored fetal movement and were referred to the hospital because of ultrasound findings of intrauterine stillbirth. Five patients were misdiagnosed with a single umbilical artery on prenatal ultrasound. Twenty patients underwent emergency cesarean section due to decreased fetal movement and unresponsive fetal monitoring; all neonates were alive. The gross examination of the placenta and cord revealed umbilical cord abnormalities in 26 patients (39.4%, 26/66). The pathological examination revealed venous, venous and arterial, and arterial thrombosis in 74.2%, 12.1%, and 13.6% of patients, respectively.Conclusions: The main manifestation of umbilical cord thrombosis was decreased or disappeared fetal movement. The importance of self-counting fetal movement should be emphasized to patients. The abnormalities in the umbilical cord are the main cause of this phenomenon. Focus on counting fetal movements, electronic fetal monitoring, and specific signs during a prenatal ultrasound can help early identification of umbilical cord thrombi. Emergency cesarean section is recommended to reduce the risk of interrupting the umbilical cord blood flow.