Splenic injury is a common result of blunt trauma, and bleeding occurs mainly inside the splenic capsule and may leak into the peritoneal space. Herein, we report a case where active bleeding occurred in the splenic artery and only leaked into the extraperitoneal space. This is the first case of this phenomenon in a trauma patient in the English-language literature. Bleeding passed through the peritoneum, leaked into the anterior pararenal space, and continued along the extraperitoneal space to the prevesical space of the pelvis. Therefore, on the initial computed tomography (CT) scan, the bleeding appeared to be in the left paracolic gutter, so we suspected mesenteric bleeding. However, after the CT series was fully reconstructed, we accurately read the scans and confirmed splenic injury with active bleeding. If there had been a suspicion of bowel or mesenteric injury, surgery would have been required, but fortunately surgery could be avoided in this case. The patient was successfully treated with angioembolization.