A rare case of inferior mesenteric arteriovenous fistula: diagnostic aspects

An arteriovenous fistula (AVF) is an abnormal connection between an artery and a vein, resulting in direct blood flow, bypassing the capillary network. Among the rarest forms is inferior mesenteric AVF, with fewer than 50 reported cases worldwide, according to recent studies. This vascular anomaly can be congenital, iatrogenic, traumatic, or idiopathic. Its clinical significance is associated with impaired intestinal hemodynamics - the development of ischemia, venous congestion, portal hypertension, and cardiac overload. This clinical observation describes a case of spontaneous inferior mesenteric AVF in a 72-year-old female patient with diabetes mellitus, hypertension, and obesity. Symptoms were limited to moderate lower abdominal pain without significant functional impairment. Computed tomography angiography (CTA) revealed early enhancement of the inferior mesenteric vein in the arterial phase - a pathognomonic sign of arteriovenous bypass grafting. Given the patient’s age, comorbidities, and the absence of significant hemodynamic disturbances, a watchful waiting approach with dynamic monitoring of laboratory and instrumental studies was chosen. This case highlights the diagnostic value of CTA as the “gold standard” for mesenteric fistulas and demonstrates the need for an individualized approach to treatment. In patients with asymptomatic cases and high surgical risk, conservative management of inferior mesenteric AVFs is a reasonable and safe solution.