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Potentially life-threatening emergency
Large bowel obstruction
Other Resources UpToDate PubMed
Potentially life-threatening emergency

Large bowel obstruction

Contributors: Brit Long MD, Taylor Reffett MD, Michael W. Winter MD, Sara Manning MD
Other Resources UpToDate PubMed


Emergent Care / Stabilization:
  • Give fluid resuscitation to patients presenting with hypovolemia or signs of shock, with pressors as needed.
  • Obtain urgent surgical consultation and administer early antibiotics for patients presenting with signs of bowel ischemia or sepsis.
  • Provide symptomatic therapy with intravenous (IV) pain medication and antiemetics.
  • Give the patient nothing by mouth.
Diagnosis Overview:
A large bowel obstruction (LBO) occurs when intraluminal contents fail to pass through the large intestine. This results in dilation of the proximal large bowel, with fluid accumulation, gas production, increased intraluminal pressure, and bacterial overgrowth. Bacterial translocation can then lead to bacteremia and sepsis.

Unlike small bowel obstructions (SBOs), LBOs often occur secondary to colorectal malignancies, accounting for 60% of all cases. Stenosis secondary to diverticular disease and volvulus account for another 30%. Other causes include compression from intra-abdominal masses and stenosis secondary to inflammatory bowel disease, radiation, or surgical anastomoses.

LBOs may be partial or complete. A simple LBO is characterized by a single point of obstruction. A closed-loop obstruction is characterized by occlusion of the bowel at 2 points and has the highest risk of ischemia due to occlusion of the blood supply. A classic example of this is sigmoid volvulus. A competent ileocecal valve may also contribute to closed loop obstructions as the large bowel cannot decompress proximally.

Patients present with severe abdominal distension and inability to pass stool or flatus. Abdominal pain due to LBO is typically less severe and more gradual in onset compared to SBO. However, patients with LBO typically have more severe distension compared to SBO, as well as nausea and vomiting.

Patients presenting secondary to colorectal malignancy often have a history of alternating diarrhea and constipation over the preceding weeks to months and may have had bleeding per rectum. A change in stool caliber and/or weight loss may be present and suggest malignancy is the cause of the LBO. Left lower quadrant (LLQ) pain can be suggestive of diverticular disease. Sigmoid volvulus is more common in older patients, those on a high-fiber diet, those with a history of chronic constipation, and long-term care facility residents. Cecal volvulus differs in that it occurs most commonly in patients between the ages of 30 and 60 years and in those with a pelvic mass, prior abdominal surgery, and in the third trimester of pregnancy.

Obstruction leads to increased colonic dilation, eventually leading to necrosis and perforation of the bowel. Patients with bowel ischemia or perforation usually have more severe presentations, often with signs of peritonitis, sepsis, and hemodynamic instability.


K56.609 – Unspecified intestinal obstruction, unspecified as to partial versus complete obstruction

281254000 – Large bowel obstruction

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

  • Small bowel obstruction – Nausea, vomiting, and abdominal pain are more prominent features. Patients often have a history of prior abdominal surgeries.
  • Ileus – Commonly occurs immediately after abdominal surgery or trauma. Imaging will show air in the colon and rectum.
  • Intestinal pseudo-obstruction (Ogilvie syndrome) – Most commonly occurs in older adults with multiple comorbidities, often with severe illness. Imaging will show air in the colon and rectum.
  • Clostridioides difficile colitis – Diarrhea is a prominent feature. Patients usually have risk factors for C difficile infection including recent antibiotic use or hospitalization. Patients may progress to fulminant colitis with toxic megacolon.
  • Toxic megacolon – Patients typically have a history of bloody diarrhea in the preceding week and often have a history of inflammatory bowel disease or risk factors for C difficile colitis.
  • Acute appendicitis – Abdominal pain may be located in the periumbilical area before migrating to the right lower quadrant (RLQ), with localized tenderness.
  • Diverticulitis – Abdominal pain is usually localized to the LLQ, and abdominal distension is less prominent. Patients often have a history of similar episodes.
  • Bowel perforation – Patients more commonly have evidence of peritonitis with guarding and abdominal rigidity and may display evidence of Bacterial sepsis. LBO can result in intestinal perforation.

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Management Pearls

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Drug Reaction Data

Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.

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Last Reviewed:01/11/2023
Last Updated:01/22/2023
Copyright © 2024 VisualDx®. All rights reserved.
Potentially life-threatening emergency
Large bowel obstruction
Imaging Studies image of Large bowel obstruction - imageId=8359789. Click to open in gallery.  caption: '<span>Coronal image from a CT scan demonstrating dilated ascending colon with large amount of stool. The remainder of the large bowel loops were also dilated, consistent with a large bowel obstruction.</span>'
Coronal image from a CT scan demonstrating dilated ascending colon with large amount of stool. The remainder of the large bowel loops were also dilated, consistent with a large bowel obstruction.
Copyright © 2024 VisualDx®. All rights reserved.