EP105 - Retroperitoneal Fistula due to Diverticulitis Treated with Minimally Invasive Surgery

Purpose/Background: Despite diverticulosis being one of the most common benign abdominal diseases encountered, complicated diverticulitis is far less prevalent. Complications of diverticulitis include bleeding, perforation, fistula, stricture, and obstruction. Fistulizing disease is thought to occur in 17-27% of surgically treated diverticulitis. These fistulas or connections between two epithelized tissues can be a major cause of morbidity.  The most common fistulas include colovesicular and colovaginal. A case of complicated diverticulitis will be discussed hereafter regarding a colovesicular fistula and a coloretroperitnoeal fistula to the iliacus muscle.

Methods/Interventions: A 70-year-old female presented to her primary physician's office for left anterior hip pain and occasional crampy left lower quadrant abdominal pain. She underwent a left hip MRI showing fluid within the iliopsoas bursa and iliacus muscle with inflammatory changes to the sigmoid colon and left hip arthrosis with complex joint effusion concerning for septic arthritis. Clinically, she was otherwise stable, without laboratory abnormalities, and ambulating independently. She presented to the ER for further workup and endorsed pneumaturia.  She underwent a subsequent CT scan showing sigmoid diverticulitis with a 5cm iliopsoas abscess, left-sided hydronephrosis, and air within the bladder (Figure). She underwent percutaneous drainage of purulent fluid and was discharged on antibiotics. After undergoing endoscopic evaluation, she presented for elective robotic sigmoidectomy with takedown of the colovesicular and coloretroperitoneal fistula. Given multiple pelvic fistulas in the setting of chronic diverticulitis, a diverting ileostomy was also planned.

Results/Outcomes: Despite difficult anatomy, the visualization and dexterity offered by the robotic platform in combination with critical surgical principles facilitated a safe surgery and a good outcome. On initial evaluation, the pelvis was obscured with a thickened rectosigmoid colon adhered to the bladder dome, uterus, and within the pouch of Douglas. The proximal sigmoid colon was densely adherent within the left pelvic inlet adjacent to the iliac vessels and ureter. The colovesicular fistula was taken down and methylene blue the leak test was negative. The distal sigmoid and rectosigmoid colon were then freed from the uterus and pouch of Douglas, the presacral space was entered distal to the sacral promontory, and the coloretroperitoneal fistula was isolated circumferentially and carefully taken close to the bowel wall. The left ureter was intimately involved and partial ureterolysis was necessary before safely taking the fistula down. A sigmoidectomy with anastomosis and diverting loop ileostomy was then completed. On postoperative day one, she did have to undergo cystoscopy with ureteral stent placement due to anuria and acute kidney injury caused by ureteral orifice inflammation. Otherwise, she recovered well.

Conclusion/Discussion: A retroperitoneal fistula due to diverticulitis is rarely described in the literature. Although a thorough data search was performed, only a few case reports have been written and even fewer have utilized minimally invasive surgery. The robotic platform allows for excellent visualization, especially in difficult locations such as the pelvis. Robotic visualization combined with fundamental surgical principles including restoring normal anatomy and respecting surgical planes allowed our patient to have a safe outcome.

CT Scan of Coloretroperitoneal Fistula
Coronal view of sigmoid to iliacus muscle fistula with air seen within the iliacus muscle.

CT Scan of Coloretroperitoneal Fistula
Axial view of igmoid to iliacus muscle fistula with air seen within the iliacus muscle.