Angiodysplasia
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In medicine (gastroenterology), angiodysplasia is a small vascular malformation of the gut. It can be a source of gastrointestinal bleeding and anemia.
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[edit] Signs, symptoms and diagnosis
Although some cases present with black, tarry stool (melena), the blood loss can be subtle, with the anemia symptoms predominating. Fecal occult blood testing is positive when bleeding is active. If bleeding is intermittent the test may be negative.
Diagnosis of angiodysplasia is often accomplished with endoscopy, either colonoscopy or esophagogastroduodenoscopy (EGD). Although the lesions can be notoriously hard to find, the patient usually is diagnosed by endoscopy. A new technique, pill enteroscopy, has been a major advance in diagnosis. With 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. In cases with negative endoscopic findings and high clinical suspicion, selective angiography of the mesenteric arteries is sometimes necessary.
[edit] Pathophysiology
Its predilection locus is the cecum, although it can develop at other places. Histologically, it resembles telangiectasia. Development is related to age and strain on the bowel wall, which is thought to influence the caliber change and proliferation of the vascular tissue.
Although angiodysplasia is probably quite common, the risk of bleeding is increased in disorders of coagulation. A classic association is Heyde's syndrome (coincidence of aortic valve stenosis and bleeding from angiodysplasia). In this disorder, von Willebrand factor (vWF) is proteolysed due to high shear stress in the highly turbulent blood flow around the aortic valve. vWF is most active in vascular beds with high shear stress, including angiodysplasias, and deficiency of vWF increases the bleeding risk from such lesions.
Warkentin et al argue that apart from aortic valve stenosis, some other conditions that feature high shear stress might also increase the risk of bleeding from angiodysplasia.
[edit] Therapy
If the anemia is severe, blood transfusion is required before any other intervention is considered. Endoscopic treatment is an initial possibility, where cautery is applied through the endoscope. Resection of the affected part of the bowel may be needed. However, the lesions may be widespread, making such treatment impractical. Embolisation through angiography is occasionally contemplated with severely bleeding lesions that cannot be visualised on colonoscopy.
Estrogens can be used to stop bleeding from angiodysplasia. Estrogens cause mild hypercoaguability of the blood. Estrogen side effects can be dangerous and unpleasant in both sexes. Changes 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/HRT, however, apply here as well.)
[edit] References
- Warkentin TE, Moore JC, Anand SS, Lonn EM, Morgan DG. Gastrointestinal bleeding, angiodysplasia, cardiovascular disease, and acquired von Willebrand syndrome. Transfus Med Rev. 2003 Oct;17(4):272-86. PMID 14571395.
