Hemorrhoids are enlarged veins located in the lower part of the rectum and the anus. The veins become swollen due to increased pressure within them, usually from constipation or profuse diarrhea, and during pregnancy because of the pressure of the enlarged uterus.
Internal hemorrhoids are located in the inside lining of the rectum and cannot be felt. They are usually painless and make their presence known because blood is seen with a bowel movement. Internal hemorrhoids can prolapse or protrude through the anus.
External hemorrhoids are located underneath the skin that surrounds the anus. They can be felt when they swell and may cause itching, pain, or bleeding with a bowel movement. A thrombosed external hemorrhoid occurs when blood within the vein clots, and may cause significant pain.
Hemorrhoids are associated with constipation and straining at bowel movements. Pregnancy is also associated with hemorrhoids. These conditions lead to increased pressure within the hemorrhoidal veins that causes them to swell. Other conditions, for example chronic liver disease, may also cause increased venous pressure and may be associated with hemorrhoids. Hemorrhoids are very common and are estimated to occur in up to one-half of the population by age 50.
Medically Reviewed by a Doctor on 2/26/2015
Bhupinder Anand, MD
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