A colostomy is a surgical procedure that brings the bowel, or colon, to the surface of the abdomen to eliminate waste. The colon, (also called large intestine or large bowel), is a long tube-like organ that transports waste from digested food to the rectum, which acts as a storage pouch. Bowel movements (wastes) are stored in the rectum until they are passed out of the body. The large bowel is approximately 5 feet long, and serves the purpose of removing water from the waste of digested food as it travels through the body. This is why when the bowel is irritated and waste moves through the colon too quickly for the extra water to be removed, diarrhea occurs. Usually in cases of appendix cancer half of the right side of the large colon, where the appendix is attached, is removed. The name for this procedure is a right hemicolectomy.
In some cases, though, when appendix cancer has spread extensively into the abdomen and affected a greater portion of the large colon, more of the large colon may be removed. In most cases, the two remaining ends of the bowel are sewn or stapled back together; they are reconnected and no colostomy is necessary. The medical word for the reconnection of the two remaining ends of the bowel is "anastamosis". In some cases, though, the two ends are not reconnected and instead a the segment of the colon carrying the waste products is brought to the outside surface of the abdomen, this is called a colostomy. The part of the colon that extends to the surface of the abdomen is called a colostomy stoma. A bag is attached to the area of the abdomen where wastes products come out of the stoma, and the waste products are collected in the bag. The bag can be emptied or changed when needed. In some cases the colostomy is only temporary, and after several months the two ends of the colon are surgically reconnected in another procedure, and bowel movements are again eliminated in the normal way. In other cases, the colostomy is permanent and the patient will have the colostomy the rest of his or her life.
In cases where the entire large colon needs to be removed, the stoma will be created from the end of the small intestine (ileum) and brought to the outer surface of the abdomen. In this case, the bowel movements, or waste, will always be liquid as there is no colon to remove the water. Instead of being called a colostomy, the term ileostomy is used as the ileum and not the colon is brought to the surface of the abdomen. Sometimes a surgical procedure can be done which creates a "continent ileostomy". In this case a pouch is created from small bowel inside of the abdomen to hold the liquid waste and a valve prevents the waste from escaping. In this case an external bag does not have to be worn and a tube is inserted several times a day into the stoma to drain the liquid bowel movement from the pouch.
See the diagram below of a colostomy from the National Cancer Institute: http://visualsonline.cancer.gov/retrieve.cfm?imageid=3900&dpi=72&fileformat=jpg
The colostomy stoma is normally dark, pink, and moist; it looks like the normal tissue on the inside of your mouth. It is usually no bigger than the size of a silver dollar. In some cases the bowel movements coming through the colostomy will be solid, as they are normally when they are passed out of the body, but in cases where a very large portion or all of the large intestine has been removed, water will not be able to be removed from the waste, so the waste will remain liquid.
Many people live a normal and long life with a colostomy. Many people continue to work and enjoy sports, including swimming, while wearing a colostomy bag. In some cases a colostomy can be regulated so that bowel movements can be anticipated and a bag may not be worn for periods of time, but instead the stoma covered with gauze pad or a "stoma cap". In some cases, an ornamental stoma cover may even be worn at times of intimacy.