Cancer Health Center

Description and Causes

A bowelobstruction may be caused by a narrowing of the intestine from inflammation or damage to the bowel, tumors, scar tissue, hernias, twisting of the bowel, or pressure on the bowel from outside the intestinal tract. It can also be caused by factors that interfere with the function of muscles, nerves, and blood flow to the bowel. Most bowel obstructions occur in the small intestine and are usually caused by scar tissue or hernias. The rest occur in the colon (large intestine) and are usually caused by tumors, twisting of the bowel, or diverticulitis. Symptoms will vary depending on whether the small or large intestine is involved.

The most common cancers that cause bowel obstructions are cancers of the colon, stomach, and ovary. Other cancers, such as lung and breast cancers and melanoma, can spread to the abdomen and cause bowel obstruction. Patients who have had abdominalsurgery or radiation are at a higher risk of developing a bowel obstruction. Bowel obstructions are most common during the advancedstages of cancer.

Assessment of Bowel Obstruction

The doctor will do a physical examination to find out whether the patient has abdominal pain, vomiting, or any movement of gas or stool in the bowel. Blood and urine tests may be done to detect any fluid and blood chemistry imbalances or infection. Abdominal x-rays and a barium enema may also be done to find the location of the bowel obstruction.

Treatment of Acute Bowel Obstruction

Patients who have abdominal symptoms that continue to become worse must be monitored frequently to prevent or detect early signs and symptoms of shock and constricting obstruction of the bowel. Medical treatment is necessary to prevent fluid and blood chemistry imbalances and shock.

A nasogastric tube may be inserted through the nose and esophagus into the stomach, or a colorectal tube may be inserted through the rectum into the colon to relieve pressure from a partial bowel obstruction. The nasogastric tube or colorectal tube may decrease swelling, remove fluid and gas build-up, or decrease the need for multiple surgical procedures; however, surgery may be necessary if the obstruction completely obstructs the bowel.

Treatment of Chronic, Malignant Bowel Obstruction

Patients who have advanced cancer may have chronic, worsening bowel obstruction that cannot be removed with surgery. Sometimes, the doctor may be able to insert an expandable metal tube called a stent into the bowel to open the area that is blocked.

When neither surgery nor a stent placement is possible, the doctor may insert a gastrostomy tube through the wall of the abdomen directly into the stomach by a very simple procedure. The gastrostomy tube can relieve fluid and air build-up in the stomach and allow medications and liquids to be given directly into the stomach by pouring them down the tube. A drainage bag with a valve may also be attached to the gastrostomy tube. When the valve is open, the patient may be able to eat or drink by mouth without any discomfort because the food drains directly into the bag. This gives the patient the experience of tasting the food and keeping the mouth moist. Solid food should be avoided because it may block the tubing to the drainage bag.

If the patient's comfort is not improved with a stent or gastrostomy tube, and the patient cannot take anything by mouth, the doctor may prescribe injections or infusions of medications for pain and/or nausea and vomiting.

Current Clinical Trials

Check NCI's list of cancer clinical trials for U.S. supportive and palliative care trials about constipation, impaction, and bowel obstruction that are now accepting participants. The list of trials can be further narrowed by location, drug, intervention, and other criteria.

General information about clinical trials is also available from the NCI Web site.