An ostomy is a surgical procedure that creates a new pathway for the body to eliminate waste when the natural route through the rectum is compromised due to injury or disease. This operation involves bringing a section of the bowel through the abdominal wall to form an opening, known as a stoma. A collection pouch is worn over the stoma to gather the diverted waste. The specific section of the digestive tract used determines whether the procedure is an ileostomy or a colostomy, leading to fundamental differences in function and management.
Understanding the Ileostomy Procedure
An ileostomy is created when the final section of the small intestine, the ileum, is brought through the abdominal wall to form the stoma. This procedure is performed when the entire large intestine, or colon, must be bypassed or removed due to disease, and the stoma is usually situated on the lower right side of the abdomen.
Since the waste bypasses the colon, which normally absorbs water and electrolytes, the output from an ileostomy is characteristically liquid or very pasty in consistency. This continuous, high-volume output results from significantly reduced water absorption.
The ileostomy stoma often protrudes slightly from the skin, which helps direct the liquid output into the collection pouch and protects the surrounding skin.
Understanding the Colostomy Procedure
A colostomy involves bringing a portion of the large intestine, or colon, through the abdominal wall to create a stoma. Unlike an ileostomy, the location of a colostomy stoma can vary significantly depending on which part of the colon is used to create the opening. The most common types are named for the section of the colon involved, such as ascending, transverse, descending, or sigmoid colostomies.
A colostomy is most frequently placed on the left side of the abdomen, specifically when the descending or sigmoid colon is utilized. However, a colostomy in the transverse colon, which runs across the upper abdomen, would result in a stoma higher up.
Because some or most of the colon remains in the digestive circuit, the waste has more time for water absorption. This means the output from a colostomy is generally semi-solid to solid and more formed than ileostomy output. The more distal the colostomy (closer to the rectum, such as a sigmoid colostomy), the more formed the stool will be, reflecting near-normal bowel function.
Functional Differences in Output and Stoma Management
The origin of the stoma dictates the nature of the output, which determines the daily management requirements. An ileostomy produces an effluent that is high in volume and consistently liquid or very thick and pasty. Conversely, a colostomy yields a lower-volume output that ranges from soft to fully formed stool. This difference in consistency directly impacts the collection system, or appliance, needed for each procedure.
Ileostomy output contains digestive enzymes that can be highly irritating and damaging to the surrounding skin. Therefore, ileostomy appliances must incorporate skin barriers that are particularly resilient and protective against enzymatic breakdown to prevent severe skin irritation.
The high fluid output of an ileostomy poses a constant risk of dehydration and electrolyte imbalance, particularly sodium and potassium loss. Patients with an ileostomy must be diligent about fluid and salt intake to compensate for the bypassed water-absorbing function of the large intestine. This risk is less pronounced with a colostomy because water and electrolytes are still absorbed by the remaining colon.
A significant difference in management is the potential for irrigation, a technique exclusively available for certain colostomies, specifically those of the descending and sigmoid colon. Irrigation involves introducing water into the stoma to stimulate a bowel movement at a predictable time. This potentially allows the patient to wear a small stoma cap instead of a full pouch between irrigations. This level of regulated emptying is not possible with the continuous, liquid output of an ileostomy.
Surgical Indications and Permanence
The medical condition requiring the diversion is the primary factor in a surgeon’s decision to perform an ileostomy or a colostomy. An ileostomy is often necessary when diseases affect the entire colon or rectum, such as severe Ulcerative Colitis, Crohn’s disease, or familial adenomatous polyposis. The procedure ensures that the diseased section of the bowel is completely bypassed or removed.
A colostomy is more commonly indicated for conditions like colorectal cancer, diverticulitis, or trauma to the lower colon or rectum. The goal of the surgery is often to divert the stool stream to allow the affected distal part of the colon or a surgical connection to heal. The specific location of the stoma is chosen to provide the maximum time for water absorption based on the extent of the disease.
Both procedures can be temporary or permanent, depending on the reason for the surgery. A temporary ostomy is created to give the downstream bowel a chance to rest and heal, with the expectation that the continuity will be surgically restored later. An ileostomy is frequently temporary, particularly when created as a protective measure following a complex rectal or pouch surgery. Conversely, a permanent ostomy is needed when the lower bowel, rectum, or anus is either removed or permanently non-functional.