Severe loin pain following renal biopsy in a high-risk patient: a case report of a rare combination of pseudoaneurysm and arterio-venous fistula.

We report a 50-year-old male patient with diabetes mellitus and hypertension who presented with low-grade fever, anuria and renal failure. He had no prior history of nephropathy and retinopathy. Since anuria persisted, a renal biopsy was performed using automated gun, under ultrasound guidance. Two hours after the renal biopsy was performed, the patient developed severe left loin pain that required analgesics and sedatives. Ultrasound of the abdomen performed immediately, two hours and four hours after the biopsy, did not reveal any hematoma. The hemoglobin was stable when the patient developed loin pain, but after eight hours decreased to 9.1 g/dL, and computed tomography scan of the abdomen revealed a big peri-nephric hematoma around the left kidney. He was managed with blood transfusions and a selective angiogram was done. It revealed a pseudoaneurysm and arterio-venous fistula from the segmental artery of lower pole of the left kidney; both were closed by using microcoils and liquid embolic agent N-butyl-cyanoacrylate (NBCA). The only risk factor the patient had at the time of renal biopsy was severe renal failure. Our case suggests that severe loin pain immediately after renal biopsy in a patient with renal failure warrants careful follow-up of hemoglobin and imaging, even if initial imaging is normal. Further fall of hemoglobin necessitates early evaluation with angiogram, which helps in diagnosing the treatable, although rare, complications like pseudoaneurysm and arterio-venous fistula.