A 62-year-old previously healthy man presented with left lower quadrant pain and fever. Physical examination showed left lower quadrant peritonitis. Computed tomography scan showed a pelvic abscess with extraluminal air (). Intravenous antibiotics were started, and CT-guided percutaneous drainage was performed. The drain was removed 1 week after discharge. One week later, he presented with dysuria and pneumaturia and was started on antibiotics. Colonoscopy confirmed diverticulosis with no other mucosal abnormalities. He underwent a successful laparoscopic sigmoidectomy with colovesical fistula takedown.