Definition and Overview
A colostomy is a surgical procedure wherein a part of the large intestine (colon) is brought out to the abdominal wall so stools are able to pass and drain outside the body via an opening. This opening is known as a stoma and is connected to an appliance and a colostomy bag.
Who Should Undergo and Expected Results
A colostomy may be recommended to patients suffering from:
Obstructions of the large intestines and rectum - A colostomy may be necessary in cases of conditions that prevent stools from exiting through the normal route. These include colorectal masses, which may be due to cancer or an infection such as tuberculosis.
Congenital malformations – These refer to congenital abnormalities that prevent normal passage of stool such as imperforate anus, recto-vaginal fistulas and large pelvic tumours.
Medical problems affecting the colon – Patients who suffer from certain conditions that affect the large intestines, such as volvulus or twisting of the bowels, or those who have experienced trauma or injuries to the colon also qualify for the procedure.
Faecal incontinence – A colostomy can be recommended for this condition if the patient has already attempted all available conservative therapies but fail to adequately address the condition. In some instances, a colostomy may have to be performed as part of a more extensive bowel surgery. In cases wherein part of the large intestines is removed, such as in colorectal cancer surgery, a stoma may be necessary to give time for the bowel to rest and heal.
Depending on the pathology and circumstances, a colostomy may be permanent (will have to be maintained for life) or temporary or reversible, meaning that the bowel can be eventually repaired and returned inside the abdomen, and gastrointestinal continuity will be reestablished. Surgery is required for the closure of a colostomy, and can usually be performed several months after, once the initial condition has been resolved.
How is the Procedure Performed?
There are several kinds of colostomies, and although the basic principle of exteriorizing the bowel is the same, the segment of the bowel to be brought out and the techniques can be quite different. The different types of colostomies are:
- Loop colostomy – This is used for emergency situations, such as in cases of complete gut obstruction. A loop of intestine is pulled out, incised, and the opening sutured to the skin. In this procedure, the stoma is usually temporary and the bowel is still continuous posteriorly.
Double barrel colostomy. This is usually performed in conjunction with bowel resection operations. In contrast to the loop colostomy, the large intestine in this procedure is severed and separated. The two ends are then brought out to the skin.
End colostomy - In this procedure, only the proximal end of the bowel is brought out. The other end is either closed off (such as in a Hartmann’s pouch) or completely removed (such as in an abdominoperineal resection).
The general procedure of performing a colostomy begins with the identification of the stoma site. A circular incision is then made in the skin, which is taken down to the subcutaneous tissues to create a cruciate incision on the rectus sheath. The abdominal muscle is separated bluntly in order for the surgeon to access the abdominal cavity. Depending on the type of colostomy to be performed, a part of the large intestine is then brought out through the incision before the bowel is sutured and secured to the skin. If the colostomy is conducted as part of a bigger procedure, it is usually the last step performed.
A colostomy is performed under general anaesthesia. After the procedure, the stoma is connected to an appliance or a pouch, which collects the stool coming from the body. Care instructions are given by a stoma nurse before the patient is discharged from the hospital.
Possible Risks and Complications
Various complications can occur with colostomies, especially when they are maintained for long periods of time. These include:
- Mild irritation of the skin near the colostomy site following contact with stool
- Development of a parastomal hernia – This refers to the protrusion of the abdominal contents adjacent to the stoma tract usually due to the weakness of the abdominal wall muscles. This occurs in approximately 10 to 25% of colostomy patients and is typically repaired with another surgery.
- Necrosis of the stoma - This is an early postoperative complication and could be due to the poor blood supply of the exteriorized segment. In such cases, the colostomy may have to be revised.
- Stomal prolapse – This is a possible complication but is not frequently encountered. It occurs when a part of the colon falls out of the stoma.
Retraction of the stoma and obstruction – These are the less common complications of the procedure.
Cima RR, Pemberton JH. Ileostomy, colostomy, and pouches. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger & Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, PA: Elsevier Saunders; 2010:chap 113.
Fry RD, Mahmoud N, Maron DJ, Bleier JIS. Colon and rectum. In: Townsend CM, Beauchamp RD, Evers BM, Mattox KL, eds. Sabiston Textbook of Surgery. 19th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 52.