Blood vessels carry blood from the heart to all organs and tissues in the body. The rectum, anus and anal opening contain many blood vessels.
Sometimes increased pressure in the rectum causes the blood vessels of the anus to become swollen; the increased pressure can result from constipation, diarrhea, pregnancy, or aging. When the blood vessels become swollen, they are called hemorrhoids, or piles.
Hemorrhoids are a very common condition. The most common cause of hemorrhoids is straining during bowel movements. Hemorrhoids can be internal, occurring inside the anus; or they can be external, occurring just under the skin at the anal opening. They can also protrude from the anus.
Some symptoms of hemorrhoids include rectal bleeding after bowel movements, painful bowel movements, and anal itching.