Ischemia a New Cause of Colovesical Fistula Resulting from Internal Iliac Artery Aneurysm Coil Embolization

Abstract

Diverticular disease is the most common cause of colovesical fistula. Colvesical fistulae are observed in postoperative settings or as a consequence of Crohn's disease. Iatrogenic fistulae are caused by surgical procedures, radiation, cancer, or infection. Other causes include foreign bodies, like swallowed chicken bones or toothpicks, in the bowel. This is the first report of an endovascular coil causing a colovesical fistula by an ischemic mechanism. A 76-year-old man with a contained rupture of a 12 cm left internal iliac artery aneurysm was treated endovascularly with coil embolization and stent placement. He had a right hemicolectomy for a colon cancer; prostate cancer treated with hormonal therapy and had undergone a Billroth II anastamosis with vagotomy for PUD in the past. A colonoscopy two years ago was normal. Eleven days post procedure he had four episodes of hematochezia with a drop in his hemoglobin and hematocrit. Coagulation profile and platelet count were normal. He denied melena, hematemesis, abdominal pain or constipation. Some feces were reported inside his urinary catheter bag but no pneumaturia was reported. His vital signs were stable. Abdomen was nontender with a central surgical scar. His rectal exam showed heme positive formed stools. Abdominal CT scan revealed no extravasation of IV contrast into the gastrointestinal tract or leak from the vascular stent. On colonoscopy, at 20 cm from the anal verge, a 4 cm fistulous opening was seen with visualization of urinary bladder wall. Cystoscopy confirmed a large fistula between the bladder and rectum at the level of the trigone distal to the ureteral orifices. During surgery a wire from the iliac artery aneurysm coils was seen sitting in the bladder causing a vesiculoaneurysmal fistula as well. The patient made an uneventful recovery post-surgical repair of the fistulas and removal of the vascular coils. Patients with colovesical fistulas may have suprapubic pain, irritative voiding symptoms, urinary tract infections and hematuria. Pneumaturia and fecaluria are seen in 40–60%. CT scanning of the abdomen and pelvis is the most sensitive test for detecting a colovesical fistula. Colonoscopy is helpful in determining the nature of the bowel disease. Treatment of the fistulas depends on the cause. Connections between the colon and urinary bladder can result from ischemia caused by coils placed for embolization.