Unusual cause of retroperitoneal hemorrhage: Acute deep vein thrombosis.

Retroperitoneal hemorrhage is rarely associated with acute deep vein thrombosis (DVT). We present a case of retroperitoneal hemorrhage due to disruption of the external iliac vein associated with acute DVT, which was carefully treated with an anticoagulant. A 78-year-old woman complained of acute abdominal pain. Contrast-enhanced computed tomography (CT) showed left retroperitoneal hematoma and venous thrombosis from just above the bifurcation of the inferior vena cava to the left femoral vein. She was admitted for conservative treatment without an anticoagulant. The next day, she developed pulmonary embolism (PE), but administration of an anticoagulant was not started because of the possibility of rebleeding. Forty-four hours after the onset of PE, unfractionated heparin was administrated intravenously. After initiation of anticoagulation, retroperitoneal hemorrhage did not expand and PE did not get worse. Follow-up contrast-enhanced CT suggested May-Thurner syndrome (MTS). She was uneventfully discharged home on the 35th day with oral warfarin. Retroperitoneal hemorrhage is rarely caused by acute DVT in the case of potential causes such as MTS. In such cases, the timing of initiation of anticoagulation is difficult considering the possibility of rebleeding from retroperitoneal hemorrhage. We should start anticoagulation based on both the state of hemostatic and preventive procedures for PE. Learning objective: Retroperitoneal hemorrhage is rarely caused by acute deep vein thrombosis because of the iliac vein rupture. The subsequent occurrence of pulmonary embolism (PE) makes it more complicated and critical because treatment strategies for these two conditions are the opposite: hemostasis versus anticoagulation. The initiation of administration of an anticoagulant should be determined based on status of patients, the procedures of hemostasis, and prevention of PE.