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Large-Bowel Obstruction

Practice Essentials

Large-bowel obstruction (LBO) is an emergency condition that requires early identification and intervention. It is important to distinguish colonic obstruction from ileus, as well as to distinguish true mechanical obstruction from pseudo-obstruction; treatment differs. See the image below. 

Contrast study demonstrates colonic obstruction at

Contrast study demonstrates colonic obstruction at the level of the splenic flexure, in this case due to carcinoma. Radiograph courtesy of Charles J McCabe, MD†.

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See Can’t-Miss Gastrointestinal Diagnoses, a Critical Images slideshow, to help diagnose the potentially life-threatening conditions that present with gastrointestinal symptoms.

Signs and symptoms

A history of bowel movements, flatus, obstipation, and associated symptoms should be obtained. Complaints in patients with LBO may include the following:

Abdominal distention

Nausea and vomiting

Crampy abdominal pain

Other symptoms that may be diagnostically significant include the following:

Abrupt onset of symptoms (suggestive of an acute obstructive event)

Chronic constipation, long-term cathartic use, and straining at stools (suggestive of diverticulitis or carcinoma)

Changes in stool caliber (strongly suggestive of carcinoma)

Recurrent left lower quadrant abdominal pain over several years (suggestive of diverticulitis, a diverticular stricture, or similar problems)

Assessment of symptoms should attempt to distinguish the following:

Complete obstruction vs partial obstruction vs ileus

Colonic lesion development history

Obstruction secondary to intussusception

Obstruction secondary to acute colonic pseudo-obstruction (ACPO), or Ogilvie syndrome

Although a complete physical examination is necessary, the examination should place special emphasis on the following key areas:

Abdomen (inspection, auscultation, percussion, and palpation) – Evaluate bowel sounds, tenderness, rigidity, guarding, and any mass or fullness

Inguinal and femoral regions – In particular, look for a possible incarcerated hernia

Rectum – Assess anal patency (in a neonate), contents of anal vault, and stool consistency; perform fecal occult blood testing as appropriate

See Presentation for more detail.


The following laboratory studies may be helpful:

Complete blood count (CBC)


Prothrombin time (PT)

Type and crossmatch

Serum chemistries

Serum lactate (if bowel ischemia is a consideration)


Stool guaiac test

Imaging modalities that may be considered are as follows:

Plain radiography (flat and upright)

Contrast radiography with enema

Computed tomography (CT) – This is the imaging modality of choice if a colonic obstruction is clinically suspected; contrast-enhanced CT can help distinguish between partial and complete obstruction, ileus, and small-bowel obstruction

See Workup for more detail.


Initial therapy in patients with suspected LBO includes the following:

Volume resuscitation

Appropriate preoperative broad-spectrum antibiotics

Timely surgical consultation

Consideration of a nasogastric tube for severe colonic distention and vomiting

The following are emergencies that call for surgical intervention:

Closed loop obstructions

Bowel ischemia


Ileus is treated as follows:

Correction of fluid and electrolyte imbalances

Treatment of the underlying disorder

If the patient is vomiting, nasogastric decompression

Cessation of medications that slow colonic motility, if possible

Acute colonic pseudo-obstruction is treated as follows:

In the absence of perforation, conservative management (bowel rest, hydration, and management of underlying disorders) for the first 24 hours

If conservative management fails, neostigmine or colonoscopic decompression

For refractory cases or in the presence of perforation, surgical intervention

Volvulus is treated as follows:

For a sigmoid volvulus, in the absence of peritoneal signs, endoscopic reduction and decompression

For recurrence after decompression, surgical resection

For cecal or transverse colon volvulus, surgical resection and anastomosis; for poor surgical candidates, endoscopic detorsion and decompression

Intussusception is treated as follows:

Contrast enema (barium or air; much more likely to succeed in children than in adults)

If signs suggest peritonitis or perforation or contrast enema is unsuccessful, surgery

Colonic masses and strictures are treated as follows:

Endoscopic dilation and stenting of colonic obstruction (either as palliation or as preparation for surgical resection)

Surgery (left colon) – Resection without primary anastomosis or resection with primary anastomosis and intraoperative lavage

Surgery (right colon) – Right colectomy and primary anastomosis between the ileum and the transverse colon

Diverticular disease is treated as follows:

For persistent obstruction despite appropriate medical management, surgery

For recurrent disease, elective colonic resection

See Treatment and Medication for more detail.

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