Further tests such as colonoscopy or barium enema study are advised when the source of bleeding is not readily apparent from these examinations. There are two types of hemorrhoids, internal and external. Internal hemorrhoids, those occurring in the anus, can bleed and protrude during bowel movements. Their protrusion may spontaneously return or may require manual reduction. Sometimes these hemorrhoids protrude all the time.
External hemorrhoids occur in the veins underlying the skin outside the anus.
Although they may cause irritation and discomfort, a more frequent concern is developing a blood clot within the vein, termed a thrombosis. When this happens, a painful lump develops. This type of thrombosed hemorrhoid can be surgically removed in the office using a local anesthetic. Most ambulatory treatments are based on inducing inflammation and scarring of tissues in and around the hemorrhoids. The approach using an injection technique was first developed in the United States right after the Civil War.