Hemorrhoids are swollen, inflamed veins or vascular cushions (arteriovenous plexuses) in and around the anus and lower portion of the rectum.
Internal hemorrhoids are cushions of subepithelial connective tissue located near the beginning of the anal canal, about 1 inch inside the rectum, and are a normal part of the anorectum known to be present in the developing fetus and in healthy individuals. These cushions are made up of vascular tissue (arterioles, venules, and arteriolar-venular connections), connective tissue, and smooth muscle and are covered with a mucous membrane. When the cushions become enlarged, inflamed, thrombosed or prolapsed, they produce symptoms and are then referred to as hemorrhoids. Internal hemorrhoids are not innervated by cutaneous nerves and therefore do not produce pain and can remain asymptomatic.
External hemorrhoids are tiny veins located under the skin surrounding the anal opening. They are covered with epithelial layers and receive sensory impulses from the rectal nerve, making them subject to pain.
Internal and external hemorrhoids can occur at the same time or separately.
Internal hemorrhoids can also become enlarged and protrude from the anus (prolapsed), becoming external hemorrhoids.
Symptomatic hemorrhoids can be acute or chronic; recurrence is common.
http://www.mdguidelines.com/hemorrhoidsHemorrhoids are one of the most common human diseases. The disease has two main forms (acute and chronic) and manifests itself as thrombosis, inflammation, bleeding, and prolapse of hemorrhoids. Two main causes of the disease are identified; there are vascular disorders and mechanical damages.
Chronic and acute forms are identified in the course of the disease. Internal, external, and mixed types are distinguished by the form of the disease. Its chronic course is divided into four stages. Acute hemorrhoids are a complication of the chronic course and classified into three grades according to the degree of thrombosis and inflammation. This classification corresponds to the pathogenesis of hemorrhoids, is rather convenient, and provides a possibility of objectively defining indications and choosing the required treatment option in practical work in accordance with the stage and degree of the disease.
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