115 Sacrococcygeal Osteomyelitis as a Rare Complication in Patients With Ileal Pouch–Anal Anastomosis

Background: Restorative proctocolectomy with ileal pouch–anal anastomosis (IPAA) is the standard surgical approach for patients with inflammatory bowel disease or familial adenomatous polyposis requiring proctocolectomy. Although pouch-related complications, such as pouchitis, stricture, and fistula, are well recognized, sacrococcygeal osteomyelitis (SOM) has rarely been reported. The anatomical proximity of the ileal pouch to the sacrum predisposes it to direct spread or fistulizing infection in the presence of an abscess related to anastomotic leak or presacral sinus. Evidence regarding presentation, diagnosis, and treatment remains limited. Methods: We retrospectively identified 5 patients with IPAA who developed SOM using an institutional pouch registry. Patients who underwent primary IPAA between January 1, 2006, and December 31, 2024, were included. Clinical presentation, imaging, pouch disease features, management strategies, and outcomes were analyzed. Results: Five patients (3 females, 2 males) were diagnosed with sacral (3 patients) or coccygeal (2 patients) osteomyelitis after IPAA. All 5 patients underwent primary IPAA with a J-pouch configuration for ulcerative colitis. Diagnosis was confirmed using pelvic magnetic resonance imaging (MRI) in all 5 cases. The median age at diagnosis was 41 years (IQR, 37–59 years), and the median body mass index (BMI) was 27.0 kg/m2 (IQR, 23.3–27.7 kg/m2). The median time from pouch creation to SOM diagnosis was 11.6 years (IQR, 1.5–12.7). Three patients had pouch-related fistulas extending to the coccyx/sacrum, and 2 presented with pouch anastomotic leaks. Presacral fluid collection was observed in 4 cases. All 5 patients received prolonged intravenous antibiotic therapy, with 3 subsequently transitioned to oral antibiotics during the clinical course. One patient received conservative antibiotic treatment alone, 1 underwent surgery with takedown and repair of the J-pouch fistula, washout of the presacral cavity, and diverting loop ileostomy (DLI), 1 received CT-guided drainage of the fluid collection, and 2 were managed endoscopically with pigtail catheter drain placement and endoscopic clipping closure of the leak. Osteomyelitis resolved in 3 of the 5 cases, whereas it evolved into chronic osteomyelitis in 2 cases, which are still treated with prolonged antibiotics. All 5 patients maintained normal pouch function following treatment. Conclusions: Coccygeal and sacral osteomyelitis are rare but serious complications of IPAA, mostly arising from anastomotic leaks, fistulae, and presacral abscesses. Diagnosis is frequently delayed due to nonspecific symptoms, but MRI provides reliable confirmation of the diagnosis. While prolonged antibiotic therapy is the cornerstone of treatment, source control is required to preserve pouch function in patients with IPAA and SOM. Surgical source control, including fecal diversion, pouch excision, and debridement, may be required in severe SOM cases. Endoscopic management of leaks, fistulas, or abscesses in combination with antibiotic treatment of SOM is an attractive, low-risk, minimally invasive option that may be considered in selected cases, potentially avoiding more extensive surgery.