Retroperitoneal bleeding is relatively rare and a potentially life-threatening condition with significant mortality. Early recognition requires a high index of suspicion. Increased life expectancy, the widespread use of anticoagulants, and the rise of endovascular interventions have caused an increase in the incidence of retroperitoneal bleeding. We present a case of a 74-year-old woman who died because of retroperitoneal bleeding caused by retroperitoneal metastasis of a sigmoid carcinoma with angioinvasive growth into a lumbar artery. In addition we discuss etiology, diagnostic management, and treatment strategy.