A colostomy is an opening (stoma) in the large intestine (colon), or the surgical procedure that creates one. The opening is formed by drawing the healthy end of the colon through an incision in the anterior abdominal wall and suturing it into place. This opening, often in conjunction with an attached stoma appliance, provides an alternative channel for feces to leave the body. Thus if the natural anus is not available for that job (for example, in cases where it has been removed in the fight against colorectal cancer or ulcerative colitis), an artificial anus takes over. It may be reversible or irreversible, depending on the circumstances.
There are many reasons for this procedure. Some common reasons are:
Placement of the stoma on the abdomen can occur at any location along the colon, but the most common placement is on the lower left side near the sigmoid where a majority of colon cancers occur. Other locations include the ascending, transverse, and descending sections of the colon.
People with colostomies must wear an ostomy pouching system to collect intestinal waste. Ordinarily the pouch must be emptied or changed a couple of times a day depending on the frequency of activity; in general the further from the anus (i.e., the further 'up' the intestinal tract) the ostomy is located the greater the output and more frequent the need to empty or change the pouch.
People with colostomies who have ostomies of the sigmoid colon or descending colon may have the option of irrigation, which allows for the person to not wear a pouch, but rather just a gauze cap over the stoma, and to schedule irrigation for times that are convenient. To irrigate, a catheter is placed inside the stoma, and flushed with water, which allows the feces to come out of the body into an irrigation sleeve. Most colostomates irrigate once a day or every other day, though this depends on the person, their food intake, and their health.
A man in the UK has been given a remote-controlled bowel. Colostomy or ileostomy is now rarely performed for rectal cancer, with surgeons usually preferring primary resection and internal anastomosis, e.g. an ileo-anal pouch. In place of an external appliance, an internal ileo-anal pouch is constructed using a portion of the patient's lower intestine, to act as a new rectum to replace the removed original.
Pouches and the stick-on appliances to which they attach must be changed regularly. Sometimes an odor neutralizer and lubricant is squirted into a new pouch before it is attached. Two types of pouches are available: one disposable and one drainable. Most pouches are opaque and filter out air through a charcoal filter. The recommended practice is to empty such pouches when one-third full.  Appliances, in contrast with pouches, are usually replaced every three to seven days except in cases where their seals have broken contact with the skin, when they should be replaced immediately.
Even as long ago as the 1940s, surgeons conducting a review at the Cleveland Clinic (Jones and Kehm, 1946) could summarize the routine care of the permanent colostomy as usually quite satisfactory, stating that after patients recover from the initial worry prompted by the need for a colostomy, most of them learn to manage their colostomy quite well. "These patients come from all walks of life and carry on their daily work as usual. One patient stated that he could see no advantage of the normal anus over a colostomy. While this may be somewhat overstated, it is true that most people with a permanent colostomy can live a useful, happy life." They found that, just as in anyone else, dietary indiscretion was the usual factor in occasional bowel habit disruption. This historical experience has been borne out, as today the conclusion still stands that most patients can successfully manage a colostomy as part of their activities of daily living.
Jones and Kehm preferred tissue paper as a colostomy cover (held in place with a band or garment) rather than a colostomy bag. They found that irrigation of the colostomy varied with each patient's bowel habit but that most patients developed a routine of every-other-day irrigation, whereas a few needed no irrigation.
Parastomal hernia (PH) is the most common late complication of stomata through the abdominal wall, occurring in about 48% of the patients.Prolapse of bowel wall through the stoma occasionally happens and can require reoperation to repair.
Other common complications of colostomy are high output, skin irritation, prolapse, retraction, and ischemia.