Abstract
We present the case of a 64-year-old woman who developed a postoperative small bowel-cutaneous enterocutaneous fistula (ECF) following excision of a large sigmoid mesenteric duplication cyst. Mesenteric duplication cysts are rare congenital anomalies, most frequently arising in the ileum, with sigmoid involvement being exceptionally uncommon in adults. They may present with abdominal pain, mass effect, or be discovered incidentally, and complete surgical excision is the treatment of choice. However, postoperative complications such as ECF formation are uncommon and can be challenging to manage. In this case, the patient underwent elective resection of a large sigmoid mesenteric duplication cyst, which was densely adherent to adjacent small bowel loops and the anterior abdominal wall. The immediate postoperative period was complicated by persistent purulent wound discharge and localised abdominal wall erythema. Contrast-enhanced computed tomography demonstrated a fistulous tract originating from a segment of small bowel and communicating with the anterior abdominal wall skin. Microbiological cultures from wound swabs grew mixed enteric organisms, guiding targeted antibiotic therapy. Given the patient's hemodynamic stability, absence of diffuse peritonitis, and low-to-moderate fistula output, a conservative management approach was adopted. This included total parenteral nutrition to achieve bowel rest and correct nutritional deficiencies, regular wound care, and intravenous broad-spectrum antibiotics adjusted according to microbiology results. Over subsequent weeks, the fistula output progressively decreased, wound healing improved, and inflammatory markers normalised. Follow-up imaging demonstrated near-complete closure of the fistulous tract. Surgical re-intervention was avoided. This case highlights that, in appropriately selected patients, conservative management of postoperative small bowel-cutaneous fistulas can lead to excellent outcomes. Factors favouring nonoperative treatment included the patient's clinical stability, controlled sepsis, adequate nutritional support, and the absence of distal obstruction. The role of multidisciplinary care, involving surgeons, radiologists, microbiologists, and nutrition specialists, was critical in achieving a favourable result. We also underscore the rarity of sigmoid mesenteric duplication cysts in the adult population and the importance of recognising fistula formation as a possible complication when the lesion is adherent to the small bowel and anterior abdominal wall. Individualised treatment planning remains essential, balancing the risks of surgery against the potential for spontaneous fistula closure under optimal conservative care.