Snapshot A 62-year-old man is brought to the emergency room for blood in his stool this afternoon. He denies any prior episodes, straining, trauma, colon cancer, or alcohol abuse. His medical history is significant for stage 3 chronic renal failure. A physical examination yields hemoccult positive stool. Introduction Clinical definition describes small vascular malformations frequently found in the gastrointestinal (GI) tract most common vascular anomaly within the GI tract and a common cause of unexplained GI bleeding and anemia lesions are composed of ectatic, dilated, thin-walled vessels lined by endothelium alone or endothelium with small amounts of smooth muscle small arteriovenous communications may be present often multiple lesions that frequently involve the cecum or ascending colon Associated conditions end-stage renal disease von Willebrand disease aortic stenosis Epidemiology Demographics most often seen in patients older than 60 years of age ETIOLOGY Pathogenesis pathogenesis of the condition is not well understood though its development is probably related to age and strain on the bowel wall degenerative lesion that is probably a result from the venous obstruction secondary to the chronic and intermittent contraction of the colon obstruction of the submucosal veins at the level of muscularis propria leads to dilation and tortuosity of the draining areas precapillary sphincters become incompetent, which allows for the formation of arteriovenous malformations Presentation Symptoms hematochezia melena fatigue hematemesis if present in the upper GI tract shortness of breath weakness dizziness Physical exam pallor hemoccult positive stool tachycardia imaging Endoscopy preferred method options include upper endoscopy, colonoscopy, wireless video capsule endoscopy, and deep small bowel enteroscopy a combination of the methods may be necessary characteristic appearance of small (5-10mm), flat, cherry-red lesions with a fern-like pattern Computed tomography (CT) angiography may be especially useful in detecting angiodysplasias with an active hemorrhage Angiography indicated in patients with negative endoscopic/CT angiography results and high clinical suspicion allows for treatment Studies Diagnostic testing diagnostic approach diagnosis is primarily based on endoscopy done for the evaluation of gastrointestinal bleeding studies laboratory studies CBC and iron studies for evaluation of possible anemia intaoperative enteroscopy indicated in patients with significant bleeding but negative evaluation Differential Diverticulosis differentiating factors will be visible on endoscopic studies of the colon Colon/rectal cancer differentiating factors may complain of symptoms (e.g., stool changes) and will be present on colonoscopy Treatment Treatment is dependent on the level bleeding, if the lesion is not actively bleeding or is discovered incidentally on screening colonoscopy, no treatment is needed First-line endoscopic treatment with cautery or argon plasma coagulation (APC) supportive care IV fluids blood transfusion if severe anemia Second-line angiography and embolization with particles antifibrinolytics (e.g., tranexamic acid or aminocaproic acid) indicated in patients with bleeding from multiple or inaccessible sites estrogen used in patients with end-stage renal disease and von Willebrand disease other drugs such as thalidomide or octreotide Third-line surgery indicated in patients not responsive to either endoscopic or medical treatment resection of the affected part of the bowel Complications Anemia Bleeding/hemorrhage Exsanguination