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Cancer Health Center

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Gastrointestinal Complications (PDQ®): Supportive care - Patient Information [NCI] - Bowel Obstruction

A bowel obstruction is a blockage of the small or large intestine by something other than fecal impaction.

Bowel obstructions (blockages) keep the stool from moving through the small or large intestines. They may be caused by a physical change or by conditions that stop the intestinal muscles from moving normally. The intestine may be partly or completely blocked. Most obstructions occur in the small intestine.

Physical changes

  • The intestine may become twisted or form a loop, closing it off and trapping stool.
  • Inflammation, scar tissue from surgery, and hernias can make the intestine too narrow.
  • Tumors growing inside or outside the intestine can cause it to be partly or completely blocked.

If the intestine is blocked by physical causes, it may decrease blood flow to blocked parts. Blood flow needs to be corrected or the affected tissue may die.

Conditions that affect the intestinal muscle

  • Paralysis (loss of ability to move).
  • Blocked blood vessels going to the intestine.
  • Too little potassium in the blood.

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 surgery on the abdomen or radiation therapy to the abdomen have a higher risk of a bowel obstruction. Bowel obstructions are most common during the advanced stages of cancer.

Assessment includes a physical exam and imaging tests.

The following tests and procedures may be done to diagnose a bowel obstruction:

  • Physical exam: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. The doctor will check to see if the patient has abdominal pain, vomiting, or any movement of gas or stool in the bowel.
  • Complete blood count (CBC): A procedure in which a sample of blood is drawn and checked for the following:
    • The number of red blood cells, white blood cells, and platelets.
    • The amount of hemoglobin (the protein that carries oxygen) in the red blood cells.
    • The portion of the blood sample made up of red blood cells.
  • Electrolyte panel: A blood test that measures the levels of electrolytes, such as sodium, potassium, and chloride.
  • Urinalysis: A test to check the color of urine and its contents, such as sugar, protein, red blood cells, and white blood cells.
  • Abdominal x-ray: An x-ray of the organs inside the abdomen. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
  • Barium enema: A series of x-rays of the lower gastrointestinal tract. A liquid that contains barium (a silver-white metallic compound) is put into the rectum. The barium coats the lower gastrointestinal tract and x-rays are taken. This procedure is also called a lower GI series. This test may show what part of the intestine is blocked.
    Barium enema procedure. The patient lies on an x-ray table. Barium liquid is put into the rectum and flows through the colon. X-rays are taken to look for abnormal areas.
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