In medicine (gastroenterology), angiodysplasia is a small vascular malformation of the gut. It is a common cause of otherwise unexplained gastrointestinal bleeding and anemia. Lesions are often multiple, and frequently involve the cecum or ascending colon, although they can occur at other places. Treatment may be with colonoscopic interventions, angiography and emboliation, medication, or occasionally surgery.Contents ! "igns and symptoms # $iagnosis % &athophysiology ' Therapy ( )eferencesSigns and symptoms*lthough some cases present with blac+, tarry stool (melena), the blood loss can be subtle, with the anemia symptoms predominating. ,ecal occult blood testing is positive when bleeding is active. If bleeding is intermittent the test may be negative at times.Diagnosis$iagnosis of angiodysplasia is often accomplished with endoscopy, either colonoscopy or esophagogastroduodenoscopy (-.$). *lthough the lesions can be notoriously hard to find, the patient usually is diagnosed by endoscopy. * new technique, pill enteroscopy, has been a ma/or advance in diagnosis, especially in the small bowel which is difficult to reach with traditional endoscopy. 0ith this technique a pill that contains a video camera and radio transmitter is swallowed, and pictures of the small intestine are sent to a receiver worn by the patient. )ecently, multiphase 1T angiography (without positive oral contrast) has been shownto play a promising role in the diagnoses of small and large bowel angiodysplasia, especially when associated with active hemorrhage*ngiodysplasiae in the small bowel can also be diagnosed and treated with double2balloon enteroscopy, a technique involving a long endoscopic camera and overtube, both fitted with balloons, that allow the bowel to be accordioned over the camera.3!4In cases with negative endoscopic findings and high clinical suspicion, selective angiography of the mesenteric arteries is sometimes necessary, but this allows for interventions at time of the procedure. *n alternative is scintigraphy with red blood cells labeled with a radioactive mar+er5 this shows the site of the bleeding on a gamma camera but tends to be unhelpful unless the bleeding is continuous and significant.3#4Pathophysiology6istologically, it resembles telangiectasia and development is related to age and strain on the bowel wall.3%4 It is a degenerative lesion, acquired, probably resulting from chronic and intermittent contraction of the colon that is obstructing the venous drainage of the mucosa. *stime goes by the veins become more and more tortuous, while the capillaries of the mucosa gradually dilate and precapillary sphincter becomes incompetent. Thus is formed an arteriovenous malformation characteried by a small tuft of dilated vessels.3'43(4*lthough angiodysplasia is probably quite common, the ris+ of bleeding is increased in disorders of coagulation. * classic association is 6eyde7s syndrome (coincidence of aortic valve stenosis and bleeding from angiodysplasia).384 In this disorder, von 0illebrand factor (v0,) is proteolysed due to high shear stress in the highly turbulent blood flow around the aortic valve. v0, is most active in vascular beds with high shear stress, including angiodysplasias, and deficiency of v0, increases the bleeding ris+ from such lesions.3%40ar+entin et al. argue that apart from aortic valve stenosis, some other conditions that featurehigh shear stress might also increase the ris+ of bleeding from angiodysplasia.3%4TherapyIf the anemia is severe, blood transfusion is required before any other intervention is considered. -ndoscopic treatment is an initial possibility, where cautery or argon plasma coagulation (*&1) treatment is applied through the endoscope. ,ailing this, angiography and emoliation with particles is another microinvasive treatment option, which avoids the need for surgery and bowel resection. 6ere, the vessel supplying the angiodysplasia is selectively catheteried and emboliaed with microparticles.394 )esection of the affected part of the bowelmay be needed if the other modalities fail. 6owever, the lesions may be widespread, ma+ing such treatment impractical.If the bleeding is from multiple or inaccessible sites, systemic therapy with medication may be necessary. ,irst2line options include the antifibrinolytics tranexamic acid or aminocaproic acid. -strogens can be used to stop bleeding from angiodysplasia. -strogens cause mild hypercoaguability of the blood. -strogen side effects can be dangerous and unpleasant in bothsexes. 1hanges in voice and breast swelling is bothersome in men, but older women often report improvement of libido and perimenopausal symptoms. (The worries about hormone replacement therapy:6)T, however, apply here as well.)In difficult cases, there have been positive reports about octreotide 3;4 and thalidomide.3