Hemorrhoids are dilated or enlarged veins in the area of the anal canal. Sometimes hemorrhoids are referred to as piles. This swelling of tissue can be classified as internal or external depending upon the exact location of the area that is affected. Hemorrhoids are further classified as either prolapsing or non-prolapsing.

Both types of hemorrhoids are very common and may be associated with straining at stool, pregnancy, or with cirrhosis. When internal hemorrhoids enlarge, they are generally not associated with pain. The most common complaint is bright red blood on the toilet tissue or coating the stool, and the individual may have a vague feeling of anal discomfort. It is not until an internal hemorrhoid is thrombosed, infected, or when there has been erosion of the mucosal surface that pain is a feature.

Internal hemorrhoids may be classified additionally by degree of severity. First-degree internal hemorrhoids enlarge but do not prolapse.(1) Second-degree hemorrhoids bleed and prolapse with defecation, but return spontaneously.(2) Third-degree hemorrhoids prolapse with each bowel movement and sometimes with exertion related to work or simply when standing. They can be replaced with manual manipulation.(3) Fourth-degree hemorrhoids prolapse with profuse bleeding, and great pain.(4) When prolapse is not treated, hemorrhoids will usually becomes chronic as the tissue stays stretched.