Saturday, January 14, 2006

bowel obstruction (volvulus, strangulated hernia)

The most common cause of intestinal obstruction is cancer, occurring more frequently in older people. The tumor gradually grows until it completely obstructs the bowel. If the obstruction is partial, changes in bowel habits may be noted. These changes include alternating constipation and diarrhea. Prompt diagnosis and treatment may avert complete obstruction. Volvulus, a twisting or kinking of a portion of the intestines, and strangulated hernia are other causes of acute intestinal obstruction. With an obstruction symptoms may arise suddenly. The portion nearest to the obstruction becomes distended with intestinal contents, and the portion furthest away from the obstruction is empty. If the obstruction is complete, no gas or feces are expelled rectally. Peristalsis (movement of the intestine) becomes very forceful in the proximal portion as the body attempts to propel the material beyond the point of the obstruction. This can cause severe cramps, which tend to occur intermittently.
When the obstruction occurs high in the intestinal tract, vomiting usually results. If the obstruction is low in the colon vomiting usually does not occur. The patient becomes dehydrated due to an inability to take oral fluids and from losing water and electrolytes through vomiting. The failure of the mucosa to reabsorb the secretions contributes to the water and electrolyte imbalance.
The increased pressure on the bowel due to severe distention (expansion and swelling) and edema (swelling due to an accumulation of fluid) may impair circulation and lead to gangrene of a portion of the bowel. Perforation of the gangrenous bowel causes the intestinal contents to seep into the peritoneal (abdominal) cavity, resulting in peritonitis. Intestinal obstruction may prove fatal if prompt treatment is not given. Diagnosis is based on patient history and physical examination. X-ray of the intestinal tract is usually necessary.
Mechanical obstruction is usually treated surgically. The obstruction is relieved by a minor surgical procedure, such as a temporary colostomy (surgical opening between colon and surface of body) or cecostomy (surgical opening into the cecum). When the patient's condition has improved as a result of relief of the obstruction and supportive therapy, more extensive surgery may be undertaken.
A permanent colostomy may be necessary depending on the location and extent of the malignant process. Intestinal decompression, intravenous fluids, and antibiotics help stabilize the person's condition prior to surgery.
See also CANCER, COLON; AND RECTAL HERNIA.
Scherer, J. C. Introductory Medical-Surgical Nursing, 3rd ed. Philadelphia: J. B. Lippincott Co., 1982.
Steinberg, F. U. Care of the Geriatric Patient, 6th ed. St. Louis: C. V. Mosby Co., 1983.

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