The arteries and veins around the anus are named the hemorrhoidal arteries and veins. They can swell and enlarge because of increased pressure. Causes of increased pressure are constipation, pregnancy, obesity, regular heavy lifting, chronic diarrhea or eating a low fiber diet. And large swollen hemorrhoids on the outside of the anus are called external hemorrhoids and enlarged hemorrhoids inside the anus are called internal hemorrhoids.
The most common symptoms are painless bleeding, burning and itching. Hemorrhoidal pain comes with a thrombosed hemorrhoid which is a hemorrhoid that bleeds
Although hemorrhoids are the most common cause of rectal bleeding other causes such as cancer, polyps and inflammatory bowel disease need to be considered. In order to eliminate these possibilities a colonoscopy, which is a flexible telescope to view the inside of the colon and rectum, is performed.