Colon cancer and small bowel obstruction are two common reasons for surgery in the abdomen. Colon cancer is the fourth most common cancer in the United States, according to the National Institutes of Health. Small bowel obstruction is a blockage in the small intestine that prevents passage of the contents of the small bowel. Complications resulting from surgery include ileus, anastomotic leak and GI bleed.
An ileus is described by "Sabiston's Textbook of Surgery" as distension of the small bowel and a loss of the normal peristalsis that moves the contents forward. Peristalsis is the wavelike contraction that normally occurs in the small bowel and colon to move contents along the digestive tract. Normally after surgery, normal function of the bowel returns in approximately 24 to 72 hours. An ileus occurs because of drugs, metabolic disorders, neurological problems and infections. Narcotics slow peristalsis of the small and large bowel. Constipation of the large bowel is common in patients taking narcotics. An ileus of the small bowel is not uncommon in hospitalized patients taking pain medicine. Derangements of the natural chemicals of the body after surgery can lead to an ileus. If the magnesium, sodium or potassium that naturally occurs is low, there is a potential for an interruption of peristalsis. The body needs an adequate supply of these chemicals to maintain active contractions of the digestive system. Patients with spinal cord injuries can have neurological reasons for an ileus, and pneumonia or a sepsis infection can cause an ileus.
An anastomosis is the sewing together of two sections of bowel that have been resected. A leak occurs when the two ends separate. This allows bowel contents to leak into the stomach. Resections of the rectal colon are at high risk for leakage, according to Sabiston. The circulation to this area of the bowel is not as profuse as other areas and may compromise the tissue making up the anastomosis. Obesity is an independent risk factor for increased anastomotic leaks. Steroids affect healing by decreasing the availability of necessary healing factors and can cause leaks.
Significant gastrointestinal bleeding secondary to a stess ulceration occurs in less than 5 percent of cases, according to Sabiston. A stress ulcer occurs when a patient has had major surgery and cannot eat. The stomach continues to produce acid in large quantities due to stress and can eat a hole into the lining of the stomach, which will bleed. Patients who have a GI bleed and who have low blood pressure, require blood transfusion and also re-operation for the bleed, have the highest associated rate of mortality.