Small Bowel Obstruction

Small bowel obstruction is a partial or complete blockage of the small intestine, which is a part of the digestive system. Small bowel obstruction can be caused by many things, including adhesions, hernia and inflammatory bowel disorders. Symptoms, diagnosis and treatment are discussed.


What is the small bowel?

The small bowel, also called the small intestine, ranges from 20 to 30 feet long and is about 1 inch in diameter. It has many folds that allow it to fit into the abdominal cavity. One end of the small bowel is connected to the stomach and the other to the large intestine.

The small intestine consists of 3 parts: the duodenum, the jejunum and the ileum. Partly digested food passes from the stomach to the small intestine, where the final digestive processes occur. Nutrients, vitamins, minerals and water are absorbed by its lining.


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What is small bowel obstruction?

Small bowel obstruction is a partial or complete blockage of the small intestine. If the small bowel is functioning normally, digested products will continue to flow onward to the large intestine. An obstruction in the small bowel can partly or completely block contents from passing through. This causes waste matter and gases to build up in the portion above the blockage. It could also interfere with the absorption of nutrients and fluids.

Symptoms and Causes

What causes small bowel obstruction?

Small bowel obstruction can occur in people of all ages. There are many common causes and risk factors, including:

  • Adhesions: These are bands of scar tissue that may form after abdominal or pelvic surgery. An earlier abdominal surgery is the leading risk factor for small bowel obstruction in the United States.
  • Hernias: Segments of the intestine may break through a weakened section of the abdominal wall. This creates a bulge where the bowel can become obstructed if it is trapped or tightly pinched in the place where it pokes through the abdominal wall. Hernias are the second most common cause of small bowel obstruction in the United States.
  • Inflammatory disease: Inflammatory bowel disorders such as Crohn’s disease or diverticulitis can damage parts of the small intestine. Complications may include narrowing of the bowel (strictures) or abnormal tunnel-like openings (fistulas).
  • Malignant (cancerous) tumors: Cancer accounts for a small percentage of all small bowel obstructions. In most cases, the tumor does not begin in the small intestine, but spreads to the small bowel from the colon, female reproductive organs, breasts, lungs or skin.

What are the symptoms of small bowel obstruction?

Symptoms of small bowel obstruction may include the following:

Diagnosis and Tests

How is small bowel obstruction diagnosed?

  • Medical history: The doctor will ask the patient about any previous abdominal or pelvic surgeries or relevant procedures that have been done.
  • Physical examination: The doctor will examine the abdominal area for signs of swelling, pain, masses, bulges or hernias, surgical scars, or tenderness.
  • Blood tests: A complete blood count and electrolyte analysis will be done.

In cases where patients have fever, low blood pressure, or rapid heartbeat, other lab tests may be needed, including:

  • Abdominal X-rays: Basic X-rays can sometimes show whether the small bowel is obstructed.
  • Computed tomography (CT scan): A CT scan may be done to confirm a diagnosis and give more accurate information about the cause and the site of obstruction.

Management and Treatment

How is small bowel obstruction treated?

  • Hospitalization: Patients with an intestinal obstruction are hospitalized. Treatment includes intravenous (in the vein) fluids, bowel rest with nothing to eat (NPO), and, sometimes, bowel decompression through a nasogastric tube (a tube that is inserted into the nose and goes directly to the stomach).
  • Anti-emetics: Medications may be required to relieve nausea and vomiting.
  • Surgery: If the small intestine is completely blocked or strangulated, surgery may be needed. The goals of surgery are to identify and treat the causes of bowel obstruction. At times, segments of the bowel may need surgery. The diseased segment may need to be re-sectioned and removed.
Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 03/20/2019.

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