The location of a stoma on the abdomen is not a single fixed point but a carefully chosen site determined by surgical necessity and individual anatomy. A stoma is a surgically created opening, or diversion, that provides an exit point on the abdominal wall for waste products to leave the body. Its exact placement is unique to each person, yet it follows general anatomical guidelines based on the organ being diverted. This personalized approach ensures the stoma is functional and manageable.
Understanding What a Stoma Is
A stoma is created during an ostomy procedure, which becomes necessary when a portion of the digestive system or the urinary tract is diseased, damaged, or requires time to heal. This opening is formed by bringing a segment of the intestine or a conduit from the urinary system through the abdominal muscles and attaching it to the skin surface. The flow of feces or urine is diverted into a collection pouch worn externally on the abdomen.
The need for a stoma can be temporary, allowing the lower bowel or bladder to rest before a reversal procedure, or it may be permanent due to the removal of a diseased organ. The stoma allows the body to continue its necessary functions of waste elimination by bypassing the usual exit route.
Stoma Location Based on Ostomy Type
The general abdominal location of a stoma is primarily dictated by the specific organ being diverted, which categorizes the ostomy type. Stomas are typically situated in the lower half of the abdomen. An ileostomy, which diverts the small intestine (specifically the ileum), is most commonly placed on the lower right side. The output from an ileostomy is generally liquid or paste-like, as it bypasses the large intestine where water is absorbed.
A colostomy, which involves diverting the large intestine (colon), is usually located on the left side of the abdomen, often in the lower left quadrant. This is because the descending and sigmoid sections of the colon are naturally situated on the left. Since the waste travels further through the colon, a colostomy often yields a more solid output than an ileostomy.
The precise location of a colostomy is variable and depends on which part of the colon is brought to the surface. For example, a colostomy involving the ascending colon would be placed on the right side, similar to an ileostomy. A urostomy, which reroutes the urinary tract, is typically situated in the lower right quadrant of the abdomen, using a small segment of the small intestine to create a channel for urine.
Individual Factors Influencing Stoma Placement
While the organ determines the general side of the abdomen, the exact site is highly personalized and pre-determined by a surgeon or specialty nurse. This pre-operative marking process is performed while the patient is standing, sitting, and lying down to observe how the abdominal wall changes shape. The goal is to select a spot that remains flat and smooth in all positions.
The placement must avoid areas that could compromise the adherence of the collection pouch, such as skin folds, creases, scars, and bony prominences like the hip bone. Positioning the stoma within the rectus abdominis muscle, which runs vertically down the front of the abdomen, is preferred to offer muscle support and reduce the risk of a parastomal hernia. The chosen site must also be easily visible and reachable by the patient to ensure effective stoma care management.
Other lifestyle factors are considered, including where the patient’s beltline or clothing waistband rests, to prevent pressure or trauma to the stoma. For individuals with a more rounded abdomen, the stoma may be positioned slightly higher to ensure it sits on a flatter surface and is visible for self-care. This careful, individualized placement is fundamental to securing a reliable seal for the ostomy appliance and promoting independence.
Appearance and Sensation of the Stoma
Once surgically created, a healthy stoma presents a specific physical appearance. It is typically moist and a pink or reddish-pink color, similar to the mucous membrane lining the inside of the mouth. This color indicates a rich blood supply necessary for tissue health.
A stoma usually protrudes slightly from the skin, often about one inch, which helps direct waste into the collection pouch and away from the skin. It will be round or oval in shape. While it appears swollen immediately following surgery, it gradually shrinks to its final size over the first six to eight weeks. The stoma has no sensory nerve endings, meaning a person cannot feel it when it is touched.