Colostomy: An alternative exit from the colon created to divert waste through a hole in the colon and through the wall of the abdomen. A (colostomy is commonly performed by severing the colon to attach the end leading to the stomach to the skin through the wall of the abdomen. The end of the colon that leads to the rectum is closed off and becomes dormant. This is known as a "Hartmann's Colostomy". There are other types of colostomy procedures, but this one is the most common. Usually a colostomy is performed for infection, blockage, or in rare instances, severe trauma of the colon. This is not an operation to be taken lightly. It demands the close attention of both patient and doctor. A colostomy is often performed so that an infection can be stopped and/or the affected colon tissues can heal.