An intestinal obstruction is a partial or complete blockage of the small or large intestine. Surgery is sometimes necessary to relieve the obstruction.
Purpose
The small intestine is composed of three major sections: the duodenum just below the stomach; the jejunum, or middle portion; and the ileum, which empties into the large intestine. The large intestine is composed of the colon, where stool is formed; and the rectum, which empties to the outside of the body through the anal canal. A blockage that occurs in the small intestine is called a small bowel obstruction, and one that occurs in the colon is a colonic obstruction.
There are numerous conditions that may lead to an intestinal obstruction. The three most common causes of small bowel obstruction are adhesions, which are bands of scar tissue that form in the abdomen following injury or surgery; hernias, which develop when a portion of the intestine protrudes through a weak spot in the abdominal wall; and cancerous tumors. Adhesions account for approximately 50% of all small bowel obstructions, hernias for 15%, and tumors for 15%. Other causes include volvulus, or formation of kinks or knots in the bowel; the presence of foreign bodies in the digestive tract; intussusception, which occurs when a portion of the intestine telescopes or pulls over another portion; infection; and congenital defects. While most small bowel blockages can be treated with the administration of intravenous (IV) fluids and decompression of the bowel by the insertion of a nasogastric (NG) tube, surgical intervention is necessary in approximately 25% of patients with a partial obstruction, and 50%–65% of patients with a complete obstruction.
An obstruction of the large intestine is less common than blockages of the small intestine. Blockages of the large bowel are usually caused by colon cancer; volvulus; diverticulitis (inflammation of sac-like structures called diverticula that form in the intestines); ischemic colitis (inflammation of the colon resulting from insufficient blood flow); Crohn's disease (a disease that causes chronic inflammation of the intestines); inflammation due to radiation therapy; and the presence of foreign bodies. As in the case of small bowel obstruction, most patients with a blockage of the large intestine can be treated with IV fluids and bowel decompression.
Demographics
Approximately 300,000 intestinal obstruction repairs are performed in the United States each year. Among patients who are admitted to the hospital for severe abdominal pain, 20% have an intestinal obstruction. While bowel obstruction can affect individuals of any age, different conditions occur at higher rates in certain age groups. Children under the age of two, for example, are more likely to present with intussusceptions or congenital defects. Elderly patients, on the other hand, have a higher rate of colon cancer.
Description
After the patient has been prepared for surgery and given general anesthesia, the surgeon usually enters the abdominal cavity by way of a laparotomy, which is a large incision made through the patient's abdominal wall. This type of surgery is sometimes referred to as open surgery. An alternative to laparotomy is laparoscopy, a surgical procedure in which a laparoscope (a thin tube with a built-in light source) and other instruments are inserted into the abdomen through small incisions. The internal operating field is then visualized on a video monitor that is connected to the scope. In some patients, the technique may be used for abdominal exploration in place of a laparotomy. Laparoscopy is associated with faster recovery times, shorter hospital stays, and smaller surgical scars, but requires advanced training on the part of the surgeon as well as costly equipment. Moreover, it offers a more limited view of the operating field.
Treating an intestinal obstruction depends on the condition causing the blockage. Some of the more common surgical procedures used to treat bowel obstructions include:
Lysis of adhesions. The process of removing these bands of scar tissue is called lysis. After the abdominal cavity has been opened, the surgeon locates the obstructed area and delicately dissects the adhesions from the intestine using surgical scissors and forceps.
Hernia repair. This procedure involves an incision placed near the location of the hernia through which the hernia sac is opened. The herniated intestine is placed back in the abdominal cavity and the muscle wall is repaired.
Resection with end-to-end anastomosis. "Resection" means to remove part or all of a tissue or structure. Resection of the small or large intestine, therefore, involves the removal of the obstructed or diseased section. Anastomosis is the connection of two cut ends of a tubular structure to form a continuous channel; the anastomosis of the intestine is most often accomplished with sutures or surgical staples.
Resection with ileostomy or colostomy. In some patients, an anastomosis is not possible because of the extent of the diseased tissue. After the obstruction and diseased tissue is removed, an ileostomy or colostomy is created. Ileostomy is a surgical procedure in which the small intestine is attached to the abdominal wall; waste then exits the body through an artificial opening called a stoma and collects in a bag attached to the skin with adhesive. Colostomy is a similar procedure with the exception that the colon is the part of the digestive tract that is attached to the abdominal wall.
Diagnosis/Preparation
To diagnose an intestinal obstruction, the physician first gives a physical examination to determine the severity of the patient's condition. The abdomen is examined for evidence of scars, hernias, distension, or pain. The patient's medical history is also taken, as certain factors increase a person's risk of developing a bowel obstruction (including previous surgery, older age, and a history of constipation). A series of x rays may be taken of the abdomen, as a definitive diagnosis of obstruction can be made by x ray in 50–60% of patients. Computed tomography (CT; an imaging technique that uses x rays to produce two-dimensional cross-sections on a viewing screen) or ultrasonography (an imaging technique that uses high-frequency sounds waves to visualize structures inside the body) may also be used to diagnosis intestinal obstruction.
Unless a patient presents with symptoms that indicate immediate surgery may be necessary (high fever, severe pain, a rapid heart beat, etc.), a course of IV fluids, NG decompression, and antibiotic therapy is usually prescribed in an effort to avoid surgery.
Aftercare
After surgery, the patient's NG tube remains until bowel function returns. The patient is closely monitored for signs of infection, leakage from an anastomosis, or other complications.
Risks
Complications associated with intestinal obstruction repair include excessive bleeding; infection; formation of abscesses (pockets of pus); leakage of stool from an anastomosis; adhesion formation; paralytic ileus (temporary paralysis of the intestines); and reoccurrence of the obstruction.
Normal results
Most patients who undergo surgical repair of an intestinal obstruction have an uneventful recovery and do not experience a recurrence of the obstruction.
Morbidity and mortality rates
The mortality rate of small bowel obstruction ranges from 2% for a simple obstruction to 25% for a strangulation obstruction that compromises the blood supply and is treated after a lapse of 36 hours. Large bowel obstruction carries a mortality rate of 2% for volvulus to 40% if part of the bowel is gangrenous.
Alternatives
Such nonsurgical techniques as the administration of IV fluids and bowel decompression with a NG tube are often successful in relieving an intestinal obstruction. Patients who present with more severe symptoms that are indicative of a bowel perforation or strangulation, however, require immediate surgery.
BOOKS
Bitterman, Robert A., and Michael A. Peterson. "Large Intestine." In Rosen's Emergency Medicine. 5th ed. St. Louis, MO: Mosby, Inc., 2002.
Evers, B. Mark. "Small Bowel." In Sabiston Textbook ofSurgery. Philadelphia, PA: W. B. Saunders Company, 2001.
"Mechanical Intestinal Obstruction." In The Merck Manual ofDiagnosis and Therapy, edited by Mark H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 1999.
Torrey, Susan P., and Philip L. Henneman. "Small Intestine." In Rosen's Emergency Medicine. 5th ed. St. Louis, MO: Mosby, Inc., 2002.
PERIODICALS
Basson, Marc D. "Colonic Obstruction." eMedicine, September 26, 2001 [cited May 2, 2003]. <http://www.emedicine.com/med/topic415.htm>.
Khan, Ali Nawaz, and John Howat. "Small-Bowel Obstruction." eMedicine, April 18, 2003 [cited May 2, 2003]. <http://www.emedicine.com/radio/topic781.htm>.
ORGANIZATIONS
American Society of Colon and Rectal Surgeons. 85 W. Algonquin Rd., Suite 550, Arlington Heights, IL 60005. (847) 290-9184. <www.fascrs.org>.
United Ostomy Association, Inc. 19772 MacArthur Blvd., Suite 200, Irvine, CA 92612-2405. (800) 826-0826. <www.uoa.org>.
Stephanie Dionne Sherk
WHO PERFORMS THE PROCEDURE AND WHERE IS IT PERFORMED?
Ileoanal anastomoses are usually performed in a hospital operating room. Surgery may be performed by a general surgeon or a colorectal surgeon, a medical doctor who focuses on the surgical treatment of diseases of the colon, rectum, and anus.
