Diversion of the faecal stream with the distal colon left in situ can occur following both elective and emergency surgery for colonic disease. Whether the excluded colon is subsequently removed or continuity restored is variable. In patients undergoing subtotal colectomy for colitis, the majority will undergo a further procedure, either a restorative ileroectal anastomosis or completion proctectomy, with or without an ileoanal pouch. Amongst those patients who undergo Hartmann’s procedure, the rates of reversal varies widely, but a significant proportion will not undergo further surgery and remain with a permanent colostomy and rectal stump. In patients undergoing elective anterior resection of the rectum for adenocarcinoma, a significant proportion of patients will have a permanent stoma with distal colon in situ. Both acute and chronic complications may result from the redundant distal colon. In the acute postoperative period, such complications include pelvic sepsis resulting from rectal stump dehiscence. Chronic complications, which are more common in those in whom the original surgery was for inflammatory bowel disease, include on-going disease activity in the rectum, and in the long term, dysplastic changes and carcinoma. Where the original pathology was not inflammatory, those with a rectal stump may develop non-specific inflammatory changes in the rectum, so-called diversion colitis, as a consequence of diversion of the faecal stream. Diversion colitis may present with abdominal pain, bleeding and discharge. Here, we describe the late presentation of inflammatory change within a rectal stump resulting in massive distension of the rectum and significant haemorrhage. The rectal distension caused bladder outflow obstruction, bilateral hydronephrosis and acute renal failure requiring bilateral nephrostomies. At the age of 29, a male patient underwent investigation for life-long constipation. A barium enema showed gross colonic distension. It was decided to proceed with a subtotal colectomy, and in light of the technical difficulties anticipated as a consequence of the gross colonic distension, this was planned as a two-stage procedure. He initially underwent a difficult subtotal colectomy with an end ileostomy, though when he was readmitted for planned reversal of his stoma and an ileorectal anastomosis, the rectum was, during laparotomy, found to be distended. It was, therefore, not felt safe to perform an anastomosis; the rectum was left in place, and the ileostomy was refashioned. The patient was content not to pursue any further surgical intervention. Fifteen years later, the patient presented as an emergency complaining of rectal bleeding and anal pain. On this occasion, his symptoms settled spontaneously, and outpatient flexible sigmoidoscopy of the rectum was planned. He was readmitted in the interim complaining of abdominal distension, difficulty passing urine and further rectal bleeding. On examination, he was normotensive and pyrexial with a temperature of 41°C. His abdomen was distended, with a palpable tender bladder. He was unable to tolerate rectal examination. His blood tests revealed acute renal impairment, with a creatinine of 220, a urea of 16.7, potassium of 5.6, WCC 12.9, and CRP 166. He was catheterised and drained 1,800 ml of urine; urinalysis was positive for blood and nitrates. He was started on broad spectrum intravenous antibiotics. An ultrasound of the renal tract demonstrated bilateral hydronephrosis. He went on to have bilateral nephrostomies, with a consequent improvement in his renal function. A CT of Int J Colorectal Dis (2008) 23:1143–1144 DOI 10.1007/s00384-008-0491-3