Idiopathic inferior mesenteric arteriovenous fistula with bleeding diarrhea: A case report.

RATIONALE: The inferior mesenteric arteriovenous fistula (IMAV AVF) is an anomalous connection between the arteries and veins of the mesentery, bypassing the capillary network and typically involving the hepatic, superior mesenteric, and splenic arteries. PATIENT CONCERNS: A 64-year-old previously healthy male presents with a 2-month history of bloody and watery diarrhea with lower abdominal pain, and a notable 10-kg weight loss. DIAGNOSES: A diagnosis of ischemic colitis (IC) was supported by a colonoscopy that revealed diffuse ulcerations and stenosis from the sigmoid-descending colon junction to the upper rectum. The nidus of the inferior mesenteric artery (IMA)V AVF was observed by digital subtraction angiography to emerge from the IMA and empty into the inferior mesenteric vein. IC and IMAV AVF were confirmed pathologically. INTERVENTIONS: We performed a low anterior resection to completely resect the AVM and postoperative pathology confirmed IMAV AVF. An end colostomy was created. OUTCOMES: The patient was ultimately diagnosed with IMAV AVF. LESSONS: The diagnosis of exclusion is commonly used for idiopathic IMAV AVF. Clinicians should consider patients exhibiting gastrointestinal symptoms similar to those associated with IC as potential candidates for the diagnosis of this disease. Based on the patient's condition, rational selection of endovascular and surgical treatment is necessary.