Hemorrhoids, also called "piles," are swollen tissues that contain veins. They are located in the wall of the rectum and anus and may cause minor bleeding or develop small blood clots. Hemorrhoids occur when the tissues enlarge, weaken, and come free of their supporting structure. This results in a sac-like bulge that extends into the anal area.
Hemorrhoids are unique to humans - no other animal develops them. They are very common - up to 86% of people will report they have had hemorrhoids at some time in their life, though people often use this as a catch-all label for any ano-rectal problem including itching. They can occur at any age but are more common as people get older. Among younger people, they are most common in women who are pregnant.
Although they can be embarrassing to talk about, anyone can get hemorrhoids, even healthy young people in good shape. They can be painful and annoying but aren't usually serious. Hemorrhoids differ depending on their location and the amount of pain, discomfort, or aggravation they cause.
Internal hemorrhoids are located up inside the rectum. They rarely cause any pain, as this tissue doesn't have any sensory nerves. These hemorrhoids are graded for severity according to how far and how often they protrude into the anal passage or protrude out of the anus (prolapse):
- Grade I is small without protrusion. Painless, minor bleeding occurs from time to time after a bowel movement.
- A grade II hemorrhoid may protrude during a bowel movement but returns spontaneously to its place afterwards.
- In grade III, the hemorrhoid must be replaced manually.
- A grade IV hemorrhoid has prolapsed - it protrudes constantly and will fall out again if pushed back into the rectum. There may or may not be bleeding. Prolapsed hemorrhoids can be painful if they are strangled by the anus or if a clot develops.
External hemorrhoids develop under the skin just inside the opening of the anus. The hemorrhoids may swell and the area around it may become firm and sore, turning blue or purple in colour when they get thrombosed. A thrombosed hemorrhoid is one that has formed a clot inside. This clot is not dangerous and will not spread through the body, but does cause pain and should be drained. External hemorrhoids may itch and can be very painful, especially during a bowel movement. They can also prolapse.