Hemorrhoid

A hemorrhoid is an enlarged or inflamed vascular cushion in the anal canal or around the anus. It may cause bleeding, pain, itching, or no symptoms.

Anal cushions: Normal vascular and connective-tissue structures in the anal canal that help seal the anus. Hemorrhoids arise when these normal cushions enlarge or descend.
Rectal bleeding: Passage of blood from the rectum or anus, with causes ranging from benign disease to cancer. Hemorrhoids can cause bleeding, but blood should not automatically be attributed to them.
Constipation: Infrequent or difficult passage of stool, often involving hard stools or straining. Straining and hard stools can aggravate hemorrhoidal symptoms.
Anal fissure: A tear in the lining of the anal canal that commonly causes sharp pain during defecation. A fissure often causes severe defecation pain unlike uncomplicated internal hemorrhoids.
Internal hemorrhoid: An enlarged anal cushion above the dentate line, often causing painless bleeding or prolapse. Its position above the dentate line helps explain why it is often painless.
Anorectal pain: Pain arising from the anus or rectum, with causes including fissures, abscesses, and thrombosis. Pain patterns help distinguish uncomplicated hemorrhoids from other conditions.
Valsalva maneuver: Forced exhalation against a closed airway that raises pressure in the chest and abdomen. Repeated straining during defecation can increase pressure on anal cushions.
Perianal abscess: A localized collection of pus in tissue around the anus, usually causing persistent pain and swelling. An abscess can resemble a painful external hemorrhoid but requires prompt treatment.
External hemorrhoid: An enlarged vein beneath the skin around the anal opening, sometimes forming a painful clot. Its sensitive skin covering can make swelling or thrombosis painful.
Rubber band ligation: A procedure that places a tight band around an internal hemorrhoid to cut off its blood supply. It is a common office treatment for symptomatic internal hemorrhoids.

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