Bowel obstruction
Other namesIntestinal obstruction
Upright X-ray demonstrating small bowel obstruction.jpg
Upright abdominal X-ray demonstrating a small bowel obstruction. Note multiple air fluid levels.
SpecialtyGeneral surgery
SymptomsAbdominal pain, vomiting, bloating, not passing gas[1]
ComplicationsSepsis, bowel ischemia, bowel perforation[1]
CausesAdhesions, hernias, volvulus, endometriosis, inflammatory bowel disease, appendicitis, tumors, diverticulitis, ischemic bowel, tuberculosis, intussusception[2][1]
Diagnostic methodMedical imaging[1]
TreatmentConservative care, surgery[2]
Frequency3.2 million (2015)[3]
Deaths264,000 (2015)[4]

Bowel obstruction, also known as intestinal obstruction, is a mechanical or functional obstruction of the intestines which prevents the normal movement of the products of digestion.[2][5] Either the small bowel or large bowel may be affected.[1] Signs and symptoms include abdominal pain, vomiting, bloating and not passing gas.[1] Mechanical obstruction is the cause of about 5 to 15% of cases of severe abdominal pain of sudden onset requiring admission to hospital.[1][2]

Causes of bowel obstruction include adhesions, hernias, volvulus, endometriosis, inflammatory bowel disease, appendicitis, tumors, diverticulitis, ischemic bowel, tuberculosis and intussusception.[1][2] Small bowel obstructions are most often due to adhesions and hernias while large bowel obstructions are most often due to tumors and volvulus.[1][2] The diagnosis may be made on plain X-rays; however, CT scan is more accurate.[1] Ultrasound or MRI may help in the diagnosis of children or pregnant women.[1]

The condition may be treated conservatively or with surgery.[2] Typically intravenous fluids are given, a tube is placed through the nose into the stomach to decompress the intestines, and pain medications are given.[2] Antibiotics are often given.[2] In small bowel obstruction about 25% require surgery.[6] Complications may include sepsis, bowel ischemia and bowel perforation.[1]

About 3.2 million cases of bowel obstruction occurred in 2015 which resulted in 264,000 deaths.[3][4] Both sexes are equally affected and the condition can occur at any age.[6] Bowel obstruction has been documented throughout history, with cases detailed in the Ebers Papyrus of 1550 BC and by Hippocrates.[7]

Signs and symptoms

Depending on the level of obstruction, bowel obstruction can present with abdominal pain, swollen abdomen, abdominal distension, and constipation.

Bowel obstruction may be complicated by dehydration and electrolyte abnormalities due to vomiting; respiratory compromise from pressure on the diaphragm by a distended abdomen, or aspiration of vomitus; bowel ischemia or perforation from prolonged distension or pressure from a foreign body.

In small bowel obstruction, the pain tends to be colicky (cramping and intermittent) in nature, with spasms lasting a few minutes. The pain tends to be central and mid-abdominal. Vomiting may occur before constipation.[citation needed]

In large bowel obstruction, the pain is felt lower in the abdomen and the spasms last longer. Constipation occurs earlier and vomiting may be less prominent. Proximal obstruction of the large bowel may present as small bowel obstruction.[citation needed]


Small bowel obstruction

Upright abdominal X-ray demonstrating a small bowel obstruction. Note multiple air fluid levels.

Causes of small bowel obstruction include:[2]

After abdominal surgery, the incidence of small bowel obstruction from any cause is 9%. In those where the cause of the obstruction was clear, adhesions are the single most common cause (more than half).[9]

Large bowel obstruction

Upright abdominal X-ray of a person with a large bowel obstruction showing multiple air fluid levels and dilated loops of bowel.

Causes of large bowel obstruction include:

Outlet obstruction

Outlet obstruction is a sub-type of large bowel obstruction and refers to conditions affecting the anorectal region that obstruct defecation, specifically conditions of the pelvic floor and anal sphincters. Outlet obstruction can be classified into four groups.[10]


A small bowel obstruction as seen on CT
Small bowel dilation on CT scan in adults[11]
<2.5 cm Non-dilated
2.5-2.9 cm Mildly dilated
3-4 cm Moderately dilated
>4 cm Severely dilated
Average inner diameters and ranges of different sections of the large intestine.[12]

The main diagnostic tools are blood tests, X-rays of the abdomen, CT scanning, and ultrasound. If a mass is identified, biopsy may determine the nature of the mass.

Radiological signs of bowel obstruction include bowel distension and the presence of multiple (more than six) gas-fluid levels on supine and erect abdominal radiographs.[medical citation needed] Ultrasounds may be as useful as CT scanning to make the diagnosis.[13]

Contrast enema or small bowel series or CT scan can be used to define the level of obstruction, whether the obstruction is partial or complete, and to help define the cause of the obstruction. The appearance of water-soluble contrast in the cecum on an abdominal radiograph within 24 hours of it being given by mouth predicts resolution of an adhesive small bowel obstruction with sensitivity of 97% and specificity of 96%.[14]

Colonoscopy, small bowel investigation with ingested camera or push endoscopy, and laparoscopy are other diagnostic options.

Differential diagnosis

Differential diagnoses of bowel obstruction include: