A bowel obstruction is a partial or complete blockage of the intestines that prevents the normal passage of substances, including gas, fluids and solids, through the intestines.

A bowel obstruction is characterized by an inability to defecate properly. The urge to defecate is typically present, but something is blocking the stool from exiting the anus. Other symptoms of a bowel obstruction include bloating, abdominal pain, nausea, vomiting and constipation.

A bowel obstruction may result from a mechanical (physical) blockage. A similar condition is an ileus, which is the loss of intestinal peristalsis (movement). Both of these are serious conditions. that requires immediate medical attention. If left untreated, the intestine may rupture and leak its contents, causing inflammation and infection of the abdominal cavity and its lining (peritoneum), a condition called peritonitis.

Common causes of mechanical intestinal obstruction include adhesions, hernias, foreign bodies and fecal impaction, among others. Factors that can increase a patient’s risk of mechanical bowel obstruction include laparotomy (abdominal surgery), inflammatory bowel disease (especially Crohn's disease), diverticular disease, cancer and radiation therapy.

The diagnosis of a bowel obstruction typically involves an evaluation of the patient’s medical history, a physical examination and a series of diagnostic imaging tests (e.g., x-ray, CAT scan). Hospitalization of the patient is always required for the treatment of bowel obstruction.

Treatment will depend on the underlying cause and type of obstruction. In the case of partial obstructions, nonsurgical treatments (e.g., nasogastric aspiration) are usually the first line of treatment. These measures allow the bowel to decompress. Other types of treatment for a partial obstruction include the use of liquids (enemas), small mesh tubes (stents for malignancy) or medications to open up the blockage. 

Abdominal surgery, called laparotomy, is generally necessary for a complete or strangulating obstruction (when blood flow is cut off to the intestine). Procedures to prevent recurrence of a bowel obstruction are also performed during laparotomy. These include the repair of hernias and removal of foreign bodies and adhesions if present.

A bowel obstruction is a partial or complete blockage of the intestines that prevents the normal passage of substances, including gas and food (both fluid and solid), through the intestines. When blockage occurs in the small intestine, it is called small intestine obstruction and when it occurs in the large intestine, it is referred to as large intestine or colonic obstruction.

When food is consumed, it enters the mouth and travels through the esophagus, stomach, small intestine and finally the large intestine, before waste (stool) is expelled through the anus. A patient with a bowel obstruction is unable to defecate properly. The urge to defecate is typically present, but something is blocking the stool from exiting the body.

The small intestine is composed of the duodenum, jejunum and ileum. Obstruction of this organ most commonly occurs in the top and middle sections, the duodenum and jejunum. Obstruction can occur in all three sections of the large intestine (the cecum, colon and rectum).

When a bowel obstruction occurs, the part of the intestine above the obstruction continues to function. The intestine then enlarges as it fills up with food, fluid, digestive secretions and gas, causing its lining to become swollen and inflamed. Stool is unable to move through and becomes trapped. Bowel obstructions may be partial or complete.

Intestinal pseudo obstruction is a condition that causes similar symptoms, but upon examination no obstruction can be found. It is caused by a problem in the muscles or nerves of the intestines, and may result from disease (e.g., Parkinson’s disease) or the use of certain medications (e.g., narcotic pain relievers, antidepressants).

Bowel obstructions may occur during the advanced stages of cancer. The most common cancers that cause bowel obstruction include colon, stomach and ovarian cancer. Other types of cancer (e.g., lung cancer) can spread to the abdomen and cause obstruction. Sometimes bowel function may be altered in cancer without actual spread of the cancer to the intestines (paraneoplastic syndrome). 

A bowel obstruction may result from either a mechanical (physical) blockage or the loss of intestinal peristalsis (movement), a condition known as ileus. When ileus occurs, the intestinal muscles are unable to contract and as a result, food cannot move through the intestines normally.

Ileus commonly occurs for one to three days following abdominal surgery, after which normal bowel function returns. Temporary ileus does not normally cause any problems. However, ileus may also develop after surgical complications (e.g., infection, blood clot), following an injury to an intestinal artery or vein, or as a result of atherosclerosis (hardening of the arteries) that reduces the blood supply to the intestine.

Known risk factors for ileus include kidney or thoracic disease, an underactive thyroid gland and metabolic imbalances, such as low potassium or high calcium levels. The use of medications, especially opioid analgesics (narcotic pain relievers) and anticholinergic drugs, may also cause ileus.

In newborns and infants, a mechanical bowel obstruction may be caused by a birth defect, such as occurs in intussusception (when one part of the intestine folds into another) and Hirschsprung's disease (condition in which the colon lacks some nerves), or a hard mass of intestinal contents (meconium).

Common causes of mechanical intestinal obstruction in adults include:

• Adhesions. The most common cause of small bowel obstruction. These are bands of scar tissue that can bind normally separate organs together, especially the intestines. Adhesions can develop following an inflammatory infection, abdominal surgery or injury.
  
  
• Hernias. Blockage can occur when a portion of the intestine bulges through an abnormal opening (hernia), such as a weakness in the abdominal wall, and becomes trapped or pinched. The most common type of hernia resulting in obstruction is an inguinal hernia. In severe cases, it may cut off blood supply to the small intestine.
  
  
• Neoplasms (benign or cancerous tumors). These lesions can cause blockage of the small or large intestine either by pressing on the outside of the intestine and pinching it closed, or by growing within the wall of the intestine and slowly blocking its passageway.
  
  
• Foreign bodies (including bezoars). Undigestible objects can impair the digestive process and result in a bowel obstruction.
  
  
• Fecal impaction. A trapped mass of hardened feces in the colon or rectum can result in blockage. This occurs more frequently in older adults and pregnant women.
  
  
• Volvulus. An abnormal twisting of a segment of the intestine around itself. This twisting typically results in blockage of the intestine.
  
  
• Gallstones. Hard masses formed from substances in bile, these stones usually contain cholesterol and/or bilirubin (substance that results from the breakdown of red blood cells), and they can develop in the gallbladder or bile ducts. These can sometimes result in obstruction of the small intestine if they enter the organ by an abnormal inflammatory passage (fistula).  
  
  
• Peptic Ulcers. The narrowed outlet from the stomach that may develop due to ulcers can result in obstruction.
  

  

Known risk factors for a mechanical bowel obstruction include:

• Laparotomy. Patients who have undergone abdominal surgery are at increased risk of developing scar tissue (adhesions), which can cause obstruction in the small intestine.
  
  
• Inflammatory bowel disease (e.g., Crohn's disease). The chronic inflammation and irritation of tissue in the alimentary canal can result in narrowing (stenosis) of the intestines, causing them to become blocked or obstructed.
  
  
• Diverticular disease. When small pouches form in the colon and become inflamed due to infection, scars can form in the wall of the colon as it heals. This scar tissue can gradually narrow the colon, causing it to become blocked or obstructed.
  
  
• Cancer and radiation therapy. In the large intestine, obstruction may be caused by cancer. The most common cancers that cause bowel obstruction include colon, stomach and ovarian cancer. Other types of cancer, such as lung and breast cancer, can spread to the abdomen and cause obstruction. Bowel obstructions are most common during the advanced stages of cancer. Patients who undergo radiation are also at increased risk of developing a bowel obstruction due to any resulting injury.

A bowel obstruction is characterized by an inability to defecate properly. The urge to defecate is typically present, but something is blocking the stool from exiting the anus. Patients with a bowel obstruction may also experience:

• Abdominal pain. Pain is associated with both small and large intestinal obstructions. The pain tends to start suddenly in small intestine obstruction and more gradually in large intestine obstruction. However, pain may be severe if the blood supply is cut off to any part of the intestines. This is called a strangulating obstruction and requires emergency medical treatment.
  
  
• Diarrhea (only during a partial obstruction), sometimes accompanied by gastrointestinal bleeding which may be indicated by bloody stools.
  
  
• Halitosis (bad breath). A bowel obstruction can cause the breath to smell like feces.

Other signs and symptoms of bowel obstruction include fever, abdominal distention (swelling), nausea and vomiting, bloating, constipation and loss of appetite.

A bowel obstruction is a serious condition that requires immediate medical attention. Patients experiencing any signs or symptoms indicative of an intestinal obstruction should promptly contact their physician for a health evaluation.

A bowel obstruction may be diagnosed by a physician during a physical examination that includes a medical history. Patients may also be referred to a gastroenterologist (a physician that specializes in the function and disorders of the digestive system).

During the physical examination, the physician may press on the abdomen to check for fullness or tenderness, and may use a stethoscope to listen for sounds in the intestines. A physician may also perform a digital rectal exam. This exam involves inserting a gloved, lubricated finger into the rectum to check for bleeding, blockage or tenderness. During the evaluation of medical history, patients will typically be asked about their bowel habits, symptoms, diet and any medications they may be taking, both prescription and nonprescription. Blood tests and urinalysis will usually be ordered to rule out infection and check electrolyte levels.

The symptoms of bowel obstruction and other gastrointestinal conditions, especially intestinal pseudo obstruction (causes similar symptoms, but no obstruction can be found), are very similar. Because of this, the diagnosis of bowel obstruction occurs only after imaging tests are performed. Depending on the suspected location of the obstruction (small or large intestine) these may include:

• X-ray. An image may be taken of the chest and abdomen on film paper or fluorescent screens. It is produced by using low doses of radiation. X-rays may show dilated loops of intestine that indicate the location of the obstruction. These images may also show air around the intestine or under the diaphragm. Air, which is not normally found in these areas, is a sign of a ruptured intestine, which will require immediate medical treatment.
  
  
• Computed axial tomography (CAT) . A test that allows for multiple x-rays to be taken from different angles around the patient. It creates images of organs and bones within the body. A CAT scan is useful in detecting if strangulation is present (when blood supply to the small intestine is impaired).
  
  
• Endoscopy. A diagnostic exam in which a tube containing an optical camera (endoscope) is fed through the mouth, passing though the esophagus into the stomach. This exam allows a physician to view the inside of hollow organs or body cavities and locate the obstruction site.
  
  
• Upper GI series. A test in which an x-ray is taken after the patient ingests liquid barium. Typically, images are taken of the stomach along with the esophagus, duodenum or both. An upper GI series can reveal the cause of obstruction to the small intestine, but is not performed when a large intestine obstruction is suspected.
  
  
• Colonoscopy. If a physician suspects blockage in the colon, this exam may be ordered. During a colonoscopy, a physician uses a long, slender tube attached to a video camera and monitor (called a colonoscope). The tube is inserted in the patient’s rectum and guided up through the colon, which allows the physician to view the patient’s entire colon and rectum.
  
  If the obstruction is caused by a volvulus (abnormal twisting of a segment of the intestine around itself), a physician can use the colonoscope not only to confirm a diagnosis, but also to attempt to untwist the intestine and relieve the obstruction. The procedure takes 15 minutes to an hour and requires a sedative. In rare cases, though, a colonoscopy may cause bleeding or perforation of the colon wall.
  
  
• Lower GI series. During this type of x-ray testing, a chemical compound containing barium is administered into a patient’s rectum via a tube (enema). The barium outlines the colon and rectum, which can help reveal the cause of a large intestine obstruction.

A bowel obstruction is a serious condition that requires immediate medical attention. If left untreated, the intestine can rupture and leak its contents, causing inflammation and infection of the abdominal cavity and its lining (peritoneum), a condition called peritonitis.

Treatment of a bowel obstruction usually begins immediately after a diagnosis has been confirmed, and hospitalization of the patient is always required. Treatment will depend on the underlying cause and type of obstruction. In the case of partial obstructions, nonsurgical treatments are usually the first line of treatment.

For a partial obstruction, a physician will typically perform a nasogastric aspiration. During this procedure, a long, thin nasoenteral tube is inserted through a patient’s nose and placed in the stomach or intestine. Suction is then applied to the tube to remove substances (e.g., food, gas, fluids) that have accumulated above the blockage. If the obstruction is in the colon, however, a physician will insert a colorectal tube through the rectum into the colon to relieve pressure. The nasoenteral or colorectal tube may decrease swelling and remove fluid and gas build-up.

Other types of treatment for a partial obstruction include the use of liquids (enemas), small mesh tubes (stents for malignancy) or medications (e.g., dexamethasone for inflammation) to open up the blockage. For example, fecal impaction is often treated by moistening and softening the stool with an enema. Sometimes, patients may need to have stool manually removed from the rectum after it is softened. Glycerin suppositories may also be administered to assist in the manual removal of feces. In some cases, a bowel obstruction resolves without further treatment. The patient is also administered fluids and electrolytes intravenously (into a vein) to restore water and salts lost through vomiting or diarrhea. It should be noted that the patient is not allowed to eat or drink anything until intestinal function normalizes or resumes. Patients are provided nutrition through a vein (parenteral nutrition) until the bowel function returns.

Surgery (laparotomy), however, is almost always necessary for a complete or strangulating obstruction (when blood flow is cut off to the intestine). Surgery is performed while the patient is under general anesthesia (agent that eliminates pain and sensation and induces unconsciousness). A physician will make an incision in the patient’s abdomen. Then the site of the bowel obstruction is located and the obstruction is relieved. Procedures to prevent recurrence of a bowel obstruction are also performed during laparotomy. These include the repair of hernias, removal of foreign bodies and complete removal of adhesions if present.

During a laparotomy, a physician will also examine the intestine for any signs of injury or ischemia (lack of blood flow). If necessary, the surgeon will remove injured or strangulated sections of the intestine and stitch the healthy ends of the intestine together, a procedure that is called resection. If resection is not possible, a physician will perform ostomy surgery, a procedure that involves bringing out the ends of the intestine through an opening created in the abdomen. Stool can then pass through this hole into an ostomy pouch.

In the case of patients with advanced cancer with chronic bowel obstruction, a physician may insert a gastrostomy tube through the wall of the abdomen directly into the stomach. A gastrostomy can relieve excess gas and fluid in the stomach.

Some patients who undergo surgery for bowel obstruction will experience complications including bowel leaks, formation of scar tissue (adhesions) and temporary paralysis of the bowels (pseudo-obstruction). In some cases, surgery to repair bowel obstruction can cause bowel obstruction. Surgery for bowel obstruction also carries the typical risks associated with any surgery, such as bleeding and infection. Patients also may have a reaction to anesthesia, including breathing problems.

Recovery time after surgery for bowel obstruction varies from patient to patient and will depend greatly on the type of procedure performed.

Prognosis is generally favorable for patients who receive proper – and timely – diagnosis and treatment of a bowel obstruction, especially if they are otherwise healthy.

Though many cases of bowel obstruction cannot be prevented, a patient may be able to reduce risk factors for some forms of bowel obstruction by practicing the following:

• Eating a diet high in fiber (whole-grain cereals and breads, beans, fresh fruits and vegetables). Fiber helps bulk up and soften stool, stimulating intestinal contractions that help move food through the digestive system. Gradually adding fiber to a diet can help to avoid problems with gas or bloating.
  
  It is important to drink increased amounts of fluids while increasing fiber intake. These increases should be gradual. Suddenly eating large amounts of fiber when the body is not used to it may cause constipation.
  
  
• Avoiding excessive fats and sugar. Maintaining a balanced diet by avoiding excessive fats and sugar can help promote normal bowel function.
  
  
• Drinking plenty of fluids. Water and other fluids add bulk to stool, making bowel movements softer and easier to pass. The recommended daily amount of fluid is eight 8-ounce glasses. Caffeine (e.g., coffee, soda) and alcohol should be avoided since they have a dehydrating effect on the body.
  
  
• Exercising regularly. Exercise helps to stimulate intestinal activity, speeding the passage of food through the digestive system. Swimming, walking or engaging in other forms of exercise for at least 30 minutes on most days of the week can help promote normal bowel movements.
  
  
• Not ignoring the urge to defecate. Recognizing and responding to the body’s signals to defecate can help prevent constipation. Bowel movements that are purposefully withheld or delayed may lead to hard, dry stool that is painful to pass or becomes obstructed.

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions regarding bowel obstruction:

1. How can I tell if I have a bout of constipation or a bowel obstruction?
   
   
2. Which diagnostic tests will you perform to determine the cause of my bowel obstruction?
   
   
3. Might I have another condition with similar symptoms?
   
   
4. Does this bowel obstruction pose any danger to my overall health?
   
   
5. Does a bowel obstruction always require treatment or will it sometimes resolve on its own?
   
   
6. What are my treatment options?
   
   
7. Will my bowel obstruction require surgical treatment?
   
   
8. How long will my recovery from treatment take?
   
   
9. How can I reduce my risk for bowel obstruction?
   
   
10. Are there certain dietary changes I can make to prevent another bowel obstruction in the future?