Spontaneous Perirenal Hemorrhage Mimicking Renal Rupture in a Long-Term Hemodialysis Patient: A Case Report.

Spontaneous perirenal hemorrhage (SPH) and spontaneous renal rupture (SRR) are rare emergencies that can be radiologically indistinguishable when hematomas are large, especially in hemodialysis patients. We report a 53-year-old man on long-term hemodialysis who developed acute left flank pain 19 h after low-molecular-weight heparin. Contrast-enhanced CT suggested SRR without tumor. Urgent angiography revealed no active extravasation; empiric selective renal artery embolization was performed, but pain and anemia progressed (hemoglobin nadir 54 g/L), prompting emergency nephrectomy. Gross and microscopic pathology demonstrated an intact renal capsule with hemorrhage confined to perirenal fat and no neoplasm, cyst rupture, aneurysm, or vasculitis, confirming SPH. Uremia-associated vasculopathy and repeated anticoagulation likely increased vascular fragility; bleeding from perirenal fat with collateral supply (lumbar, adrenal, gonadal arteries) may explain embolization failure. Postoperatively, dialysis anticoagulation was temporarily switched to nafamostat mesylate and later safely resumed with low-molecular-weight heparin; at approximately 7 months after surgery, hemoglobin was 109 g/L with no recurrence. This case underscores the limits of CT specificity in large hematomas, the need to consider extracapsular bleeding when embolization fails, the role of pathology for definitive diagnosis, and the importance of early surgical exploration and individualized anticoagulation in hemodialysis patients.