Mechanical Bowel Obstruction



A mechanical bowel obstruction is a partial or complete blockage in the intestine. It can happen at any point along the intestine tract but it is more common in the small bowel. The small bowel is the upper part of the intestines and the large bowel is the lower part.

When the bowel is blocked, food and liquid cannot pass through. Over time, food, liquid, and gas build up and cause pressure and pain. Some obstructions, when left untreated, can cut off the flow of blood to the intestine. This can lead to death of the intestine tissue and serious illness.

Mechanical Bowel Obstruction
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The bowel is a muscular tube that is constantly moving to push food through. Blockage may be caused by something blocking the inside of the tube or something that stops the intestine from working well.

Most small bowel blockages are due to scar tissue. This tissue connects the bowel to the abdominal wall or other organs. This makes it hard for the bowel to work as needed. Most large bowel obstructions are caused by tumors.

Other causes of bowel obstructions include:

  • Hernia—part of intestine pokes through abdominal wall and squeezes intestine shut
  • Bowel inflammation or swelling
  • Foreign matter in the intestines
  • Impacted feces—bulk of feces becomes trapped in the rectum
  • Volvulus—twisting of the intestine
  • Intussusception —when the intestine pulls inward into itself , most common cause in children
  • Scar tissue from a previous abdominal or pelvic surgery, particularly gynecologic or gastrointestinal operations

Risk Factors

A number of intestinal conditions can increase the risk of a bowel obstruction such as:

  • Previous gastrointestinal or gynecologic surgery—can lead to scarring
  • Diverticulitis
  • Crohn’s disease
  • Hirschsprung’s disease —in infants and children
  • Cancer of the gastrointestinal tract



Symptoms of a bowel obstruction include:

  • Abdominal pain
  • Abdominal swelling
  • Abdominal cramps
  • Nausea
  • Vomiting
  • Diarrhea
  • Severe constipation
  • Bloating
  • Fever
  • Foul breath odor


You will be asked about your symptoms and medical history. A physical exam will be done. A stethoscope will be placed on your abdomen to listen for bowel sounds. Absent, or abnormal signs may suggest a bowel obstruction.

Images will be needed to confirm the obstruction. This can be done with one or more of the following:

  • Abdominal x-ray
  • Barium enema
  • Ultrasound
  • CT scan of the abdomen



Bowel obstructions can be serious, even fatal. It will need hospitalization to provide support such as:

  • IV fluids to stop dehydration
  • Antibiotics to help clear any infections

The plan to remove the blockage will depend on where it is and what is causing it. Possible treatments include:

  • Nasogastric tube—a tube is passed through your nose and down into the stomach. Fluids that have become trapped can be removed through this tube.
  • Removal of fecal impaction—Feces trapped in the rectum can be manually loosened and removed.
  • Endoscopy—A thin, lighted tube is inserted through the rectum and into the large intestine to straighten out the intestines.
  • Surgery may be needed to:
    • Remove scar tissue, tumors, foreign matter, and other causes of the blockages
    • Repair hernias
    • Remove damaged tissue


Prevention of bowel obstruction depends on the cause. Some bowel obstructions cannot be prevented. The following actions may help reduce your risk of a bowel obstruction:

  • Treat hernias promptly before they can cause a blockage.
  • Decrease the chance of constipation by:
    • Eating plenty of fiber-rich foods
    • Drinking plenty of fluids
    • Exercising regularly

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.


American College of Gastroenterology 

National Institute of Diabetes and Digestive and Kidney Diseases 


Health Canada 

The College of Family Physicians of Canada 


Abdominal adhesions and bowel obstruction. University of California, San Francisco website. Available at: Accessed December 18, 2014.

Acute intestinal pseudo-obstruction. EBSCO DynaMed Plus website. Available at: . Updated July 12, 2014. Accessed December 18, 2014.

Jackson P, Raiji M. Evaluation and management of intestinal obstruction. Am Fam Physician. 2011;83(2):159-165.