Sigmoid-gluteal fistula: a rare complication of fistulating diverticular disease.

A rare complication of diverticular disease is the formation of fistulas, most commonly either colo-vesical or colo-vaginal. We present the unusual case of a perforated sigmoid diverticulum forming a colo-gluteal fistula and presenting initially as a gluteal abscess in an otherwise asymptomatic patient. After drainage of the gluteal abscess, the patient re-presented with faecal loss from the abscess drainage site. Imaging revealed fistulous communication between the sigmoid and the left obturator internus muscle, tracking to the gluteus maximus with associated abscess and cutaneous communication to the site of previous drainage. The patient underwent an emergency Hartmann's procedure with lay open/abscess drainage of the gluteal cavity. Post-operatively the patient experienced continuing discharge from the gluteal fistula despite repeated drainage and debridement causing considerable morbidity, inconvenience and misery. Clinicians should maintain a high index of suspicion when presented with a gluteal abscess and should consider the possibility of an intra-abdominal source.