Infected Haematoma Fistulating Through Adjacent Colorectal Anastomosis Mimicking an Anastomotic Leak

Anastomotic leakage is a well-understood major complication of colorectal surgery and carries significant implications for patient morbidity and mortality. However, an infected collection fistulating through an otherwise healthy colorectal anastomosis can mimic an anastomotic leak and warrants different management to a primary anastomotic leak. Such a presentation is undocumented in the current literature. A 42-year-old man underwent an elective perineal rectosigmoidectomy (Altemeier's procedure) for full-thickness rectal prolapse. Early postoperative computed tomography (CT) imaging demonstrated a large haematoma in the rectovesical pouch. He represented 13 days later with fevers and lower abdominal pain. CT revealed that the known haematoma had evolved into an infected collection. At this stage, there was an intact anastomosis on imaging with no evidence of fistula formation or an anastomotic leak. There was a four-day delay between diagnosis and drainage of the abscess. By then, the collection had developed gas and a subsequent CT fistulogram confirmed a fistula had formed between the colorectal anastomosis and abscess, resembling an anastomotic leak. The patient was treated successfully with a diverting ileostomy and percutaneous drainage. We present a unique case of an infected haematoma fistulating rapidly through an otherwise healthy colorectal anastomosis, mimicking an anastomotic leak 17 days after an Altemeier procedure.