Inferior mesenteric arteriovenous fistula: Progress in diagnosis and management.

Inferior mesenteric arteriovenous fistula (IMAV AVF) is a rare condition involving the inferior mesenteric artery (IMA) and inferior mesenteric vein (IMV), characterized by direct arteriovenous communication. There have been no more than 50 reported cases in the literature. The condition is categorized as congenital or acquired, with unclear pathogenesis for congenital IMAV AVF and a strong association with abdominal injuries for acquired IMAV AVF. Symptoms typically include abdominal pain, gastrointestinal bleeding, and abdominal masses. Digital subtraction angiography is considered the "gold standard" for diagnosis, revealing clusters and nodules of malformed blood vessels, thickened and increased arteries, and prematurely visible and dilated draining veins. Treatment is based on effectively eliminating or relieving venous hypertension and may involve endovascular techniques or surgery, depending on the patient's condition. This article provides a comprehensive review of the epidemiology, etiology, pathogenesis, pathophysiology, clinical manifestations, imaging performance, differential diagnosis, and treatments of IMAV AVF to enhance clinical awareness and minimize clinical underdiagnosis and misdiagnosis.