An ostomy is a surgically created opening that provides a new exit route for bodily waste when the natural pathway cannot be used. This procedure is necessary due to conditions like disease, injury, or birth defects affecting the bowel or bladder.
The opening, brought out through the abdomen, is called a stoma; it is usually pink or red and moist. Because the stoma lacks a sphincter muscle, waste flow is involuntary and must be collected in an external pouch worn over the opening. Ostomy procedures are classified into three primary anatomical types, named for the section of the body from which the stoma is created.
Colostomy
A colostomy is formed from a portion of the large intestine (colon) to divert stool away from the lower digestive tract. The stoma’s location on the abdomen depends on the part of the colon utilized, which also determines the consistency of the output. Stomas created from the descending or sigmoid colon are typically placed in the lower-left quadrant of the abdomen.
Since the waste has traveled through most of the colon where water is absorbed, the output from a left-sided colostomy is usually semi-formed or solid. If the colostomy is created higher up, such as in the transverse colon, the output will be more liquid because less water has been absorbed. Colostomies are often created to allow a downstream section of the colon or rectum to heal after surgery or to bypass a blockage.
Ileostomy
An ileostomy is created from the ileum, the final section of the small intestine. This procedure is performed when the entire large intestine is diseased or removed, or when a temporary diversion is needed to protect a surgical connection. The stoma is most commonly situated in the lower-right quadrant of the abdomen.
Because an ileostomy bypasses the large intestine’s water-absorbing function, the output is significantly different from a colostomy. The waste drains as a continuous flow of liquid or porridge-like stool. This output is rich in digestive enzymes and can be highly irritating to the surrounding skin if not managed properly. Specialized pouches are required to collect the continuous flow, and patients must be vigilant about fluid and salt intake to avoid dehydration and electrolyte imbalance.
Urostomy
A urostomy is a surgical diversion of the urinary tract, allowing urine to exit the body when the bladder is removed or non-functional. This procedure is most commonly performed using a technique called an ileal conduit.
In this technique, a small segment of the ileum is surgically isolated and used to create a channel for the urine. The ureters are disconnected from the bladder and attached to one end of this segment. The other end of the ileal conduit is brought out through the abdominal wall, typically in the right lower quadrant, to form the stoma. Urine flows continuously through this conduit into an external pouching system. Because the conduit is formed from intestinal tissue, it is normal for the output to contain mucus, which is naturally secreted by the small bowel segment.
Temporary Versus Permanent Ostomies
Ostomy types are also classified by their intended duration, determined by the underlying medical condition and the extent of the surgery. A temporary ostomy is created with the intention of being reversed once the downstream tract has had sufficient time to heal. The duration can range from a few weeks to several months, allowing for recovery from issues like inflammation or infection.
A permanent ostomy is necessary when the diseased or damaged portion of the bowel or bladder, including the rectum or sphincter muscles, is removed and cannot be safely reconnected. While temporary ostomies are designed to be reversible, factors such as poor healing or disease progression may prevent reversal surgery. Urostomies, for example, are almost always permanent because they are typically performed after the bladder has been removed.