I. What every physician needs to know.

Key features:
  • Large Bowel Obstruction (LBO) can lead to bowel ischemia, perforation, sepsis.

  • LBOs may be partial or complete. Complete LBOs should be treated as medical emergencies.

  • Intestinal transit is impaired due to an obstructed colonic lumen. The lumen can be obstructed by intrinsic lesions, such as diverticular strictures or colon cancer. Extrinsic lesions compressing the lumen may also occur, such as ovarian carcinoma.

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  • Colonic dilatation can be seen on imaging proximal to the point of obstruction. In cases of ileocecal-valve incompetence, small bowel dilatation may also be seen.

Common causes:
  • 60-75% LBOs are due to neoplasms, mostly colorectal cancer.

  • 10-15% LBOs are due to volvulus. Sigmoid volvulus is more common than cecal volvulus.

  • 10% LBOs are due to diverticular strictures from chronic diverticulitis.

  • Less common etiologies include Crohn’s disease (leads to strictures), intussusception, post-surgical anastomotic strictures, external tumors causing compression (ex: ovarian cancer, endometriosis), and fecal impaction.

  • A mechanical obstruction (intrinsic or extrinsic) of the colon leads to luminal stasis, allowing more anerobic bacteria to proliferate, leading to fermentation and increased gas production. Liquid also accumulates due to outlet obstruction. Increased gas and liquid accumulation cause increased intraluminal pressure and tension leading to compromise of vascular perfusion. The end results can be bowel ischemia, necrosis, and/or perforation.

  • At first, enteric stimuli resulting from the obstruction cause an increase in propulsive activity, causing hyperactive bowel sounds. As bowel muscle fatigues, bowel sounds become hypoactive.

  • According to LaPlace’s law, the mural tension increases proportionally to the colonic radius. Because the cecum has the greatest colonic radius, the cecum is the most common site of colonic ischemia or perforation in patients with functional ileocecal valves.

II. Diagnostic Confirmation: Are you sure your patient has a large bowel obstruction?

A. History Part I: Pattern Recognition:

  • Patients with LBO typically present with acute, colicky abdominal pain and distension.

  • In complete LBO, patients exhibit failure to pass stool. Constipation leads to obstipation. The majority of patients also report failure to pass gas.

  • Patients may have nausea and vomiting, though this is less common with LBOs as compared to small bowel obstructions.

  • Obstructing lesions from malignancy may present subacutely, with symptoms worsening over an extended period.

  • Patients may complain of weight loss. Stools may be noted to decrease to “pencil-thin” stool over time or diarrhea.

B. History Part II: Prevalence:

  • Approximately 10% of patients with colorectal cancer develop LBO.

  • Colorectal cancer risk factors include: African-American race, excessive alcohol consumption, cigarette smoking, diabetes mellitus, ulcerative colitis, Crohn’s disease, history of abdominal radiation, hereditary syndromes such as Familial adenomatrous polyposis (FAP) and Hereditary Nonpolyposis Colorectal Cancer (HNPCC or Lynch Syndrome).

  • Sigmoid volvulus risk factors include: African-American race, high-fiber diet, prior abdominal surgery, prior history of volvulus, pregnancy, laxative overuse, Parkinson’s disease, Hirschsprung disease, Chagas disease.

C. History Part III: Competing diagnoses that can mimic Large Bowel Obstruction.

  • Colonic pseudo-obstruction (Ogilvie’s syndrome):

    Diffuse colonic dilatation, which may extend to the small bowel if there is an incompetent ileocecal valve.

  • Partial colonic obstruction:

    Liquid stool and gas are still able to pass through the point of narrowing.

  • Small bowel obstruction (functional or mechanical obstruction):

    Partial or complete obstruction presenting with cramping pain, nausea, vomiting, distention, and occasionally obstipation.

D. Physical Examination Findings:

  • Colicky abdominal pain.

  • Signs of peritonitis, including rebound, voluntary and involuntary guarding.

  • Abdominal distension with tympany on percussion.

  • Hyperactive, high-pitched bowels sounds at the beginning and then hypoactive bowel sounds as obstruction progresses and bowel muscles fatigue.

  • Tachycardia.

  • Fever.

  • Ascites (if malignancy is the source of obstruction).

  • Hepatosplenomegaly (if malignancy is the source of obstruction).

E. What diagnostic tests should be performed?

1. What laboratory studies (if any) should be ordered to help establish the diagnosis? How should the results be interpreted?

Lab tests are nondiagnostic and nonspecific, but several tests can support a diagnosis of advanced colonic obstruction with ischemic sequelae:

  • Low bicarbonate.

  • Acidic blood pH.

  • High lactate: can indicate progressive necrosis.

  • Leukocytosis: can indicate worsening sepsis.

  • Hyperamylasemia.

2. What imaging studies (if any) should be ordered to help establish the diagnosis? How should the results be interpreted?

  • Abdominal X-ray:

    84% sensitivity; 72% specificity.

    Caution: LBOs can be confused with acute colonic pseudo-obstruction. Consider computed tomography (CT) scans to better differentiate between the two. Incompetent ileocecal valves can make an LBO look very similar to pseudo-obstruction.

    Two views should be ordered: Supine and upright (to evaluate for free air).

  • CT scan with contrast:

    96% sensitivity; 93% specificity.

    Helpful in visualizing the site of obstruction (transition point), bowel wall edema, free air.

    May reveal supporting evidence of malignancy, including lymphadenopathy, metastases, masses, and ascites.

    Pseudo-obstruction usually shows bowel diffusely dilated all the way to the rectum with uniform bowel wall thickness, whereas LBOs usually have transition points where the bowel diameter acute narrows.

    Obstructing colon cancers will exhibit irregular, narrow strictures with asymmetrical bowel-wall thickening.

    Diverticular strictures are usually distal, located in areas with diverticuli, and exhibit symmetrical bowel-wall thickening.

  • Contrast enemas:

    96% sensitivity; 98% specificity.

    Useful test but rarely done anymore after popularization of CT scans.

  • Ultrasound:

    May be done in ICU settings to detect LBO when patients cannot be moved from the unit.

    Ultrasound is highly operator dependent.

  • Magnetic resonance imaging (MRI):

    95% sensitivity; 100% specificity.

    MRIs are less frequently used because of the long scan times required and high cost.

See Figure 1.

Figure 1

Large bowel obstruction showing dilated colon.

F. Over-utilized or “wasted” diagnostic tests associated with this diagnosis.


III. Default Management.

General Supportive Care:
  • Use history and physical exam to differentiate between partial and total mechanical obstruction.

  • Consult surgery immediately for suspected colonic obstruction.

  • Monitor vital signs.

  • Supportive treatment:

    Fluid resuscitation to avoid dehydration.

    Replete electrolytes.

    Nasogastric tube for gastric decompression if nausea/vomiting.

    There is limited efficacy in deflating the colon. However, in the late stages of LBOs, nausea and vomiting may occur and can be relieved by decompression.

  • Keep patient without food/nil per os (NPO).

  • Flexible sigmoidoscopy or colonoscopy

    Either procedure can be therapeutic in decompressing and untwisting of the sigmoid volvulus.

    Endoscopic decompression of sigmoid volvulus has a success rate of 70%-90%, however due to high recurrence rate, elective or semi-elective surgical intervention is generally recommended.

    There is low-quality data suggesting endoscopic placement of a rectal tube after endoscopic detorsion as a bridge to surgery.

  • If endoscopic detorsion is unsuccessful, surgical intervention is required for sigmoid volvulus.

  • Cecal volvulus requires surgery and is not treated endoscopically.

Obstructive Colorectal Cancer:
  • Surgical intervention

    Patients usually undergo palliative or curative partial or total colectomy.

  • Stents

    Self-expanding, metallic colorectal stents (SEMS) are used for palliation or as a bridge to definitive surgery.

    Usually placed during colonoscopy with the aid of fluosocopy.

    Stents decrease the need for temporary colostomy when used as a bridge to surgery since patients are able to undergo colonic preparation prior to surgery.

Benign Strictures:
  • Colonoscopy

    Biopsies can rule out malignant obstructions.

  • Surgical intervention

    Partial colectomies are done to relieve the obstructions.

  • Stents

    Self-expanding, metallic colorectal stents may also be used to relieve obstruction.

A. Immediate management.

  • Supportive treatment

    Electrolyte repletion.

    Fluid resuscitation.


  • Surgical consultation for possible intervention if patient has free air, necrosis, complete obstruction, or any signs of peritonitis.

  • Antibiotic coverage for gram negatives and anerobes if patient has signs of perforation or ischemic bowel.

  • Coagulation profile (in case surgery warranted).

  • Type and screen (in case surgery warranted).

  • Beta-HCG (to screen for pregnancy, if appropriate).

B. Physical Examination Tips to Guide Management.

At first presentation, partial obstruction versus complete obstruction may not be clear. Patients may be progressing to full mechanical obstruction with or without ischemic bowel and/or perforation.

Signs of clinical deterioration include:

  • Rebound tenderness and guarding.

  • Increasing abdominal distension with tympany or abdominal pain.

  • Vital signs:



    Orthostatic hypotension.


C. Laboratory Tests to Monitor Response To, and Adjustments in, Management.

  • Complete blood count (CBCs) to monitor white blood cell count.

  • Daily basic metabolic panel to monitor and correct electrolyte abnormalities.

D. Long-term management.

  • Patients with malignancy should seek treatment with surgery, radiation, and/or chemotherapy as guided by medical oncology and surgical oncology.

  • Colonic stents may occlude from tumor growth into the stent, requiring further action by either gastroenterologists or surgeons.

  • Definitive treatment for sigmoid volvulus involves surgical resection of affected bowel.

E. Common Pitfalls and Side-Effects of Management.

  • Nasogastric tubes are not needed for gastric decompression since the obstruction is distal, unless patients have intractable vomiting and severe obstruction.

  • Avoid using metoclopramide as an anti-emetic as this drug is a pro-motility agent and can exacerbate the obstruction.

IV. Management with Comorbidities.

A. Renal Insufficiency.

CT scan with intravenous contrast is relatively contraindicated in patients with renal insufficiency and acute kidney injury.

B. Liver Insufficiency.

No change in standard management.

C. Systolic and Diastolic Heart Failure.

Caution with fluid resuscitation.

D. Coronary Artery Disease or Peripheral Vascular Disease.

No change in standard management.

E. Diabetes or other Endocrine issues.

Insulin doses may need to be adjusted in patients that are NPO. Oral hypoglycemics should be discontinued.

F. Malignancy.

No change in standard management.

G. Immunosuppression (HIV, chronic steroids, etc.).

No change in standard management.

H. Primary Lung Disease (COPD, Asthma, ILD).

No change in standard management.

I. Gastrointestinal or Nutrition Issues.

No change in standard management.

J. Hematologic or Coagulation Issues.

Depending on the specific bleeding disorder, patients may need fresh frozen plasma, cryoprecipitate, platelets, and/or red blood cell preoperatively or intraoperatively.

K. Dementia or Psychiatric Illness/Treatment.

No change in standard management.

V. Transitions of Care.

A. Sign-out considerations While Hospitalized.

  • Do serial abdominal exams. If the patient is developing peritoneal signs, call surgery.

  • If patient is febrile or hemodynamically unstable, consider starting antibiotics for coverage of gastrointestinal flora (gram negatives and anerobes) in the setting of possible perforation and sepsis.

B. Anticipated Length of Stay.

  • 48 to 72 hours if obstruction resolves without surgical intervention.

  • Length of stay will be longer if patient requires surgical intervention.

C. When is the Patient Ready for Discharge.

  • Tolerating oral intake.

  • Abdominal pain and distension resolves.

  • Signs of obstruction resolved (having bowel movements, passing flatus).

D. Arranging for Clinic Follow-up.

1. When should clinic follow up be arranged and with whom?

If resolved volvulus:

  • General surgery in 2-4 weeks: volvulus commonly recurs and patients often have elective surgery to prevent future episodes.

If surgical intervention:

  • General surgery in 1-2 weeks for monitoring of recovery and planning for future procedures (if needed).

If malignancy:

  • Surgical and medical oncology in 1-2 weeks for operative planning and consideration of chemotherapy with or without radiation, respectively.

2. What tests should be conducted prior to discharge to enable best clinic first visit?

Tissue biopsy if malignancy suspected.

3. What tests should be ordered as an outpatient prior to, or on the day of, the clinic visit?


E. Placement Considerations.

For patients with LBOs due to end-stage colon cancer or other malignancies, consider palliative-care efforts, such as hospice referrals and goals of care discussions with the patient and family. Hospice and placement planning should begin several days prior to discharge.

If patient has an ostomy, patient will need ostomy training prior to discharge or the facility will need to be able to care for ostomies.

F. Prognosis and Patient Counseling.

  • Sigmoid volvulus carries a 40-50% recurrence rate. Early intervention with elective sigmoidectomy is key to preventing serious complications.

  • Emergency surgery for acute, malignant colonic obstruction has a mortality rate as high as 20%. The mortality rate decreases to 6% when the surgery is done electively.

  • Colonic stents, when used as a bridge to surgery to allow for medical optimization and bowel preparation, can permit for surgery to be delayed up to several weeks.

  • Colonic stents are successful in 76-96% of patients. The stents can function for 6 months or longer.

  • Surgical outcomes including morbidity, stoma creation rate, and primary anastomosis success rate were improved following colonic stent placement as compared to acute surgical intervention.

VI. Patient Safety and Quality Measures.

A. Core Indicator Standards and Documentation.


B. Appropriate Prophylaxis and Other Measures to Prevent Readmission.

DVT prophylaxis is indicated for patients with LBOs. These patients are usually in bed consistently. Subcutaneous heparin will need to be held before any surgical intervention. There is minimal research on prophylactic antibiotics to prevent recurrence or complications of LBOs.

VII. What’s the Evidence?

Cappell, MS, Batke, M. “Mechanical obstruction of the small bowel and colon”. Med Clin N Am. vol. 92. 2008. pp. 575-97.

Godfrey, EM, Addley, HC, Shaw, AS. “The use of computed tomography in the detection and characterisation of large bowel obstruction”. N Z Med J. vol. 30. 2009. pp. 57-73.

Halabi, WJ, Jafari, MD, Kang, CY. “Colonic volvulus in the United States: trends, outcomes, and predictors of mortality”. Annals of surgery. vol. 259. 2014. pp. 293-301.

Harrison, ME, Anderson, MA, Appalaneni, V. “The role of endoscopy in the management of patients with known and suspected colonic obstruction and pseudo-obstruction”. Gastrointestinal endoscopy. vol. 71. 2010 Apr 30. pp. 669-79.

Lepage-Saucier, M, Tang, A, Billiard, JS, Murphy-Lavallee, J, Lepanto, L. “Small and large bowel volvulus: clues to early recognition and complications”. Eur J Radiol. vol. 74. 2010. pp. 60-66.

Maddah, G, Kazemzadeh, GH, Abdollahi, A. “Management of sigmoid volvulus: Options and prognosis”. Journal of the College of Physicians and Surgeons Pakistan. vol. 24. 2014. pp. 13-7.

Saito, S, Yoshida, S, Isayama, H. “A prospective multicenter study on self-expandable metallic stents as a bridge to surgery for malignant colorectal obstruction in Japan: efficacy and safety in 312 patients”. Surgical endoscopy.. vol. 18. 2015. pp. 1-1.

Trompetas, V. “Emergency management of malignant acute left-sided colonic obstruction”. Ann R Coll Surg Engl. vol. 90. 2008. pp. 181-6.

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