Histologically, it resembles telangiectasia and development is related to age and strain on the bowel wall. 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. As time 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 characterized by a small tuft of dilated vessels. Although<unk>  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<unk> . 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<unk> s, 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<unk> .
Angiodysplasia
Gastric varices
Chorangiosis
Anorectal varices
Diverticulosis
Varicose veins
Arteritis
Rectitis