EP842 - Atypical Case of Spontaneous Rectal Mesenteric Hematoma

Purpose/Background: Mesenteric hematoma is a rare clinical condition which can be caused by blunt abdominal trauma, acute pancreatitis, vasculitis, aneurysm, connective tissue diseases, or anticoagulation. Presentation is often nonspecific, with symptoms including abdominal pain, vomiting, abdominal masses, diarrhea, and melena. Here, we present the case of a 27-year-old male who was found to have a spontaneous rectal mesenteric hematoma with no predisposing factors. To our knowledge, this is the only reported case of a spontaneous mesenteric hematoma of the rectum.

Methods/Interventions: A 27-year-old male with a past medical history of IBS-D presented to the emergency department with acute-onset bloody diarrhea, tenesmus, and severe abdominal and rectal pain. His vital signs and laboratory results were stable. In the emergency department, digital rectal examination revealed gross blood with a mucosal bulge palpable within the rectal lumen. He underwent further workup, including a CT of the abdomen and pelvis, which showed a distended rectum and rectosigmoid junction with hyperdense, asymmetric intraluminal contents concerning for mass versus hemorrhage, prompting hospital admission.

He was evaluated by GI and underwent colonoscopy, which demonstrated a large, non-circumferential, soft, and congested/bruised mass (submucosal versus prolapse) in the rectum and rectosigmoid colon. Biopsies were consistent with rectal mucosa with patchy active inflammation, focal ulceration, and focal ischemic-like changes, but no evidence of malignancy or dysplasia. At this time, he was referred to our service. On repeat digital rectal examination, he had a soft, ballotable mass; the distal end was estimated to be 2 cm from the anorectal ring.

Due to his unusual presentation, he underwent malignancy workup including CEA, CT chest, and pelvic MRI. CEA was within normal limits, and CT chest was negative. Pelvic MRI demonstrated a large, peripherally enhancing mass extending above and below the anterior peritoneal reflection, with the distal aspect measuring 2.6 cm from the anal verge. The mass demonstrated peripheral enhancement and central necrosis, measuring approximately 6.4 × 7.1 × 14.9 cm. There was circumferential involvement of the rectum and visible sigmoid colon, with extension through the colonic wall, fat stranding within the mesorectal fat, and mass effect on the distal sigmoid colon. The patient remained stable throughout his admission and was discharged home with close follow-up. Given persistent symptoms and a nondiagnostic evaluation, a decision was made to proceed with a low anterior resection.

Results/Outcomes: Final pathology of the resected specimen confirmed a predominantly circumscribed mesenteric hematoma (6.5 cm in greatest dimension), compressing the bowel wall with hemorrhage and clot extension into the muscularis propria. The patient did well postoperatively and was discharged home in stable condition.

Conclusion/Discussion: Our case of a spontaneous rectal mesenteric hematoma in an otherwise healthy young patient presented an interesting diagnostic challenge. Pathophysiology of mesenteric hematomas includes focal bleeding from mesenteric vessels into the mesenteric fat or connective tissue. This initial bleeding forms a circumscribed hematoma within the mesentery, which can expand and exert mass effect on the adjacent bowel wall, as seen in our patient. This case demonstrates the importance of considering a rectal mesenteric hematoma on the differential even in young patients when imaging and testing are inconclusive.

Colonoscopy Report
Multiple images depicting the mass in the rectum during performed colonoscopy.
MRI Pelvis T1 Coronal View
MRI pelvis (T1 weighted, coronal view) demonstrating T1 hyperintensity.