[Role of vascular disorders in the pathogenesis of ulcerative colitis and its complications].

Mucous membrane circulatory disorders in ulcerative colitis (UC) are accompanied by significant capillary plethora with endothelial nuclear swelling in the capillaries and minor veins. Some cases show the development of secondary endophlebitis with thrombi occurring in individual veins. Occasionally, there is deep vein thrombosis in the leg with pulmonary embolism. Portal vein thromboembolism is very rarely observed during autopsy. The development of extensive deep mucous membrane ulcers gives rise to destruction of the vessels of the submucous plexis and its recurrent branchlets feeding the circular muscle layer. Impaired microcirculation is confirmed by the presence of myocytic dystrophic or necrotic changes. There are large transmural ischemic necroses in the area of toxic dilatation. Connective tissue foci develop in chronic UC at the site of ischemic necroses. Long longitudinal ulcers seen in nonspecific UC and Crohn's disease are likely to be ischemic, the course of which is long contraction of tenia with vein compression.