Veins around the anus tend to stretch under pressure.
Hemorrhoids are one of the most common problems of the lower digestive tract.
Internal hemorrhoids are painless and sometimes cause a lot of bleeding. The vein may then become irritated and painful. External hemorrhoids can easily be seen or felt. When the swollen veins are scratched or broken by straining or rubbing, they begin to bleed. External hemorrhoids may also protrude, or prolapse, through the anus.