Umbilical cord hemangiomas are rare, and the natural history is poorly understood. We present a case where the clinical course was complicated by distal umbilical cord edema, episodes of proximal obstruction of umbilical artery blood flow, transient fetal pleural and pericardial effusions, and position-dependent abnormal fetal heart rate monitoring with periods of sustained fetal tachycardia. Delivery was performed for fetal growth restriction with abnormal fetal surveillance. This case highlights possible mechanisms for fetal decompensation as well as the importance of a multifaceted approach to the management of an umbilical cord mass using multiple tools for fetal assessment. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound, 2016.