Aortoenteric fistula: a rare but critical cause of small bowel bleeding discovered on capsule endoscopy

Secondary aortoenteric fistula: a narrative review of the view of the surgeon

Aortoenteric fistula (AEF) is defined as the abnormal communication between the aorta and the gastrointestinal tract. AEFs are divided into primary and secondary usually after abdominal aortic aneurysm (AAA) recovery and are a rare but quite dangerous cause of gastrointestinal bleeding that the general surgeon may face during his/her career. Secondary AEF was first described in 1953 to a 44-year-old woman 3 months after an AAA operation. This review presents the role of the surgeon in the management of secondary aortoenteric fistulas. AEFs are a rare but fatal gastrointestinal bleeding cause that the general surgeon may be asked to manage. Diagnosis requires the combination of strong clinical suspicion and the presence of a history of AAA surgery. Although a vascular surgery case, general surgeons play a role in choosing the technique of restoring the intestinal tract, which seems to be significantly related to subsequent morbidity and mortality.

Enterocutaneous Fistula: A Simplified Clinical Approach

A “fistula” is an abnormal connection between two epithelial surfaces. Fistulae are named based on the two surfaces or lumens they connect to. Fistulae form due to loss of wall integrity from an underlying insult, leading to the penetrance of an adjacent organ or epithelized surface. Common causes of small bowel fistulae include sequelae of surgical intervention, foreign body, bowel diverticula, Crohn's disease, malignancy, radiation, and infection. A histopathological analysis displays acute and/or chronic inflammation due to the underlying pathology.

A thorough history and physical examination are important components of patient evaluation. Generally, patients will present with non-specific constitutional symptoms in addition to local symptoms attributed to the fistula. In rare instances, symptoms may be severe and life-threatening. Initial laboratory workup includes complete blood count, comprehensive metabolic panel, and lactate level. Radiologic imaging is useful for definitive diagnosis and helps delineate anatomy. In practice, computed tomography (CT) is the initial imaging modality. The addition of intravenous or enteric contrast may be helpful in certain situations. Magnetic resonance imaging (MRI) may also be used in special circumstances. Invasive procedures, such as endoscopy, can assist in the evaluation of mucosal surfaces to diagnose pathology such as inflammatory processes.

Appropriate management should include optimizing nutritional status, delineating fistulous tract anatomy, skincare, and managing the underlying disease. A non-operative approach is generally accepted as the initial approach especially in the acute/subacute setting. However, operative intervention is indicated in the setting of failed non-operative management. Successful management of small bowel fistulae requires a multidisciplinary team approach.

To conclude, a small bowel fistula is a complex clinical disease, with surgical intervention being the most common cause in developed countries. The non-operative approach should be trialed before an operative approach is considered.