AUTHOR AND EDITOR INFORMATION

Section 1 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

INTRODUCTION

Section 2 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Background

Large-bowel obstruction (LBO) is an emergency condition that requires early identification and intervention. The etiology of LBO is age dependent. Distinguishing between a true mechanical obstruction and a pseudo-obstruction is important, as the treatment differs.

Pathophysiology

Mechanical obstruction of the large bowel causes bowel dilation above the obstruction. This causes mucosal edema and impaired venous and arterial blood flow to the bowel. Bowel edema and ischemia increase the mucosal permeability of the bowel, which can lead to bacterial translocation, systemic toxicity, dehydration, and electrolyte abnormalities. Bowel ischemia can lead to perforation and fecal soilage of the peritoneal cavity.

The pathophysiology of acute colonic pseudo-obstruction (ACPO) is not clear, but it is thought to result from an autonomic imbalance, which results from decreased parasympathetic tone or excessive sympathetic output. ACPO usually occurs in the setting of a wide range of medical or surgical illnesses. If untreated, colonic ischemia or perforation can occur. This syndrome is characterized by a loss of peristalsis and results in the accumulation of gas and fluid in the colon. The right colon and cecum are most commonly involved. The risk of perforation for ACPO ranges from 3-15%. The mortality rate is 15% with early care; this increases to 36% if colonic ischemia or perforation develops.¹

CLINICAL

Section 3 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

History

• Obtain history of bowel movements, flatus, obstipation (ie, no gas or bowel movement), and symptoms.
• • Major complaints include abdominal distention, nausea, vomiting, and crampy abdominal pain.
  • Abrupt onset of symptoms makes an acute obstructive event (eg, cecal or sigmoid volvulus) a more likely diagnosis.
  • History of chronic constipation, long-term cathartic use, and straining at stools implies diverticulitis or carcinoma.
  • Change in caliber of stools strongly suggests carcinoma. When associated with weight loss, likelihood of carcinoma increases.
• Colonic lesion development history
• • Right-sided colonic lesions can grow quite large before obstruction occurs because of the large capacity of the right colon and soft stool consistency.
  • Sigmoid colon and rectal tumors cause colonic obstruction much earlier in their development because the colon is narrower and the stool is harder in that area.
• Large-bowel obstruction prior to perforation
• • Obstruction that dilates the colon causes vague, visceral abdominal cramps. Pain receptors sense distention or vigorous contraction.
  • Peritonitis may ensue.
  • When giving a history of obstipation, patients may state that pants or belts are not fitting properly.
  • Intervention is necessary to prevent perforation.
• Obstruction secondary to intussusception
• • Patients may describe intermittent, crampy abdominal pain that is colicky and relieved by assuming fetal position.
  • Weight loss and fatigue are common.
• Obstruction secondary to ACPO
• • Symptoms are similar to LBO and usually develop over 3-7 days, or less commonly, over 24-48 hours.
  • Eighty-three percent of patients complain of mild/moderate pain, which is typically diffuse and colicky in nature.
  • Nausea and vomiting are not predominate complaints.
  • Fever may be present in the setting of colonic ischemia or perforation.
• Pneumaturia, mucinuria, or fecaluria may occur when fistulization of the sigmoid colon to the bladder occurs secondary to diverticulitis or cancer.

Physical

• Abdominal distention may be significant in patients with a large-bowel obstruction.
  
  
  • Bowel sounds may be normal early on but usually become quiet.
  • Abdomen is hyperresonant to percussion.
• Palpation of the abdomen reveals tenderness. Fever, severe tenderness, and abdominal rigidity are ominous signs that suggest peritonitis secondary to perforation.
• The cecum is the area most likely to perforate (following the Laplace law). Sigmoid diverticulitis and a perforated sigmoid secondary to carcinoma are clinically difficult to differentiate.
• Patients may have guaiac-positive stool if carcinoma is the etiology.
• Rectal or lower sigmoidal mass may be palpated on rectal examination. A mass or fullness may be appreciated if a tumor is present in the cecum.

Causes

• Approximately 60% of mechanical LBOs are caused by malignancies, 20% are caused by diverticular disease, and 5% are the result of colonic volvulus.²
• • Obstructions that result from tumors have a gradual onset and result from tumor ingrowth into the colonic lumen.
  • Diverticulitis is associated with muscular hypertrophy of the colonic wall. Repetitive episodes of inflammation cause the colonic wall to become fibrotic and thickened, leading to luminal narrowing.
  • Colonic volvulus results when the colon twists on its mesentery. This impairs the venous drainage and arterial inflow. Symptoms are usually abrupt.
  • • Sigmoid volvulus typically occurs in older individuals with a history of constipation and straining.
    • Cecal volvulus is caused by a congenital defect in the peritoneum, which results in inadequate fixation of the cecum. This type of volvulus generally occurs in a younger population.
  • Intussusception is primarily a pediatric disease. It is estimated that between 5% and 16% of all intussusceptions in the western world occur in adults. Approximately two thirds of adult intussusception cases are caused by tumors. Two main types of intussusception affect the large bowel.
  • • Enterocolic intussusceptions involve both the small bowel and the large bowel. These are composed of either ileocolic intussusceptions or ileocecal intussusceptions, depending on where the lead point is located.
    • Colocolic intussusceptions involve only the colon. They are classified as either colocolic or sigmoidorectal intussusceptions.
• Acute colonic pseudo-obstruction (ACPO), or Ogilvie syndrome, has many etiologies. This disorder is typically seen in elderly patients who are hospitalized with a severe illness. In a review of more than 400 cases of ACPO, only 6% of cases were idiopathic, 49% of patients had an underlying surgical disorder, and 45% had a precipitating medical disorder.¹

DIFFERENTIALS

Section 4 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Other Problems to be Considered

Colorectal carcinoma
Cecal volvulus
Intussusception
Ogilvie syndrome
Sigmoid volvulus

WORKUP

Section 5 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Lab Studies

• Obtain a blood sample for a CBC, electrolyte levels, prothrombin time (PT), and type and crossmatch.

Imaging Studies

• Obtain an upright chest radiograph and flat and upright abdominal radiographs. Chest radiographs demonstrate free air if perforation has occurred; abdominal radiographs may be diagnostic of sigmoid or cecal volvulus (ie, kidney bean appearance on the radiograph).
• Intramural air is an ominous sign that suggests colonic ischemia.
• The absence of free air does not exclude perforation (this finding may be absent in half of all perforations).
• Additional contrast studies include an enema with water-soluble contrast (ie, Gastrografin) or CT with intravenous and oral or rectal contrast.
• Contrast studies that reveal a column of contrast ending in a "bird’s beak" are suggestive of colonic volvulus.

Procedures

• Insert a nasogastric tube if the patient has been vomiting. Intravascular volume usually is depleted, and early intravenous fluid resuscitation with isotonic saline or Ringer lactate solution is necessary.

TREATMENT

Section 6 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Emergency Department Care

Initial therapy includes volume resuscitation, appropriate preoperative antibiotics, gastric decompression, and timely surgical consultation.

Consultations

Obtain early consultation from a general surgeon. Surgical intervention is frequently indicated, depending on the cause of the obstruction.

• Carcinoma
• • Left colon
  • • Surgical treatment includes resection without primary anastomosis or resection with primary anastomosis and intraoperative lavage.
    • Endoscopically placed expandable metal stents can be used to relieve the LBO, thus allowing for a primary colorectal anastomosis.
    • Palliative colorectal stents are an option in patients who are poor surgical candidates or have advanced cancer.
    • Right colonic obstructions are treated with a right colectomy and a primary anastomosis between the ileum and the transverse colon.
• Diverticulitis
• • Patients with persistent obstruction despite appropriate medical management are treated surgically. Surgical resection follows the same principles as the treatment of carcinomas.
  • Elective colonic resection is offered to patients with recurrent disease.
• Volvulus
• • Sigmoid volvulus
  • • First choice is sigmoidoscopy with volvulus reduction.
    • Second choice is sigmoid colectomy.
  • Cecal volvulus
  • • First choice is hemicolectomy.
    • Second choice is colonoscopy.
• Intussusception: Adult colonic intussusception is treated with primary colon resection without prior reduction.
• Acute colonic pseudo-obstruction
• • Underlying precipitant factors must be identified and corrected. If no perforation, pseudo-obstruction is treated with conservative management for the first 24 hours. This includes bowel rest, hydration, and management of underlying disorders.
  • Electrolyte abnormalities should be corrected, and medications that slow colonic motility (eg, narcotics, anticholinergics) should be stopped, if possible.
  • Pharmacologic treatment with neostigmine or colonoscopic decompression may be effective in cases that do not resolve with conservative management. Surgical intervention is reserved for refractory cases or cases complicated by perforation.

MEDICATION

Section 7 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Bowel obstruction frequently necessitates surgical intervention. However, antibiotics should be started in the ED. Coverage must include gram-negative aerobic and gram-negative anaerobic organisms. The following antibiotics do not represent an all-inclusive list.

Drug Category: Antibiotics

Therapy must cover all likely pathogens in the context of this clinical setting.

Drug Name	Metronidazole (Flagyl)
Description	Imidazole ring-based antibiotic active against various anaerobic bacteria and protozoa. Used in combination with other antimicrobial agents (used alone in Clostridium difficile enterocolitis).
Adult Dose	1 g IV loading dose, followed by 0.5 g IV q6h or 1 g IV q12h
Pediatric Dose	Not established
Contraindications	Documented hypersensitivity
Interactions	May increase toxicity of anticoagulants, lithium, and phenytoin; cimetidine may increase toxicity; disulfiram reaction may occur with orally ingested ethanol
Pregnancy	B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions	Adjust dose in hepatic disease; monitor for seizures and development of peripheral neuropathy

Drug Name	Aztreonam (Azactam)
Description	Monobactam that inhibits cell wall synthesis during bacterial growth. Active against gram-negative bacilli. Effective against aerobic gram-negative organisms.
Adult Dose	2 g IV q8h
Pediatric Dose	30 mg/kg IV q6h or q8h
Contraindications	Documented hypersensitivity
Interactions	Tetracyclines may reduce effects
Pregnancy	B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions	Adjust dose in renal insufficiency

Drug Name	Cefoxitin (Mefoxin)
Description	Second-generation cephalosporin indicated for management of infections caused by susceptible gram-positive cocci and gram-negative rods. Effective against aerobic and anaerobic gram-negative organisms.
Adult Dose	2 g IV q8h
Pediatric Dose	80-100 mg/kg/d IV divided tid/qid
Contraindications	Documented hypersensitivity
Interactions	Probenecid may increase effects; coadministration with aminoglycosides or furosemide may increase nephrotoxicity (closely monitor renal function)
Pregnancy	B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions	Bacterial or fungal overgrowth of nonsusceptible organisms may occur with prolonged use or repeated treatment; caution in patients with previously diagnosed colitis

Drug Name	Cefotetan (Cefotan)
Description	Second-generation cephalosporin indicated for management of infections caused by susceptible gram-positive cocci and gram-negative rods.
Adult Dose	2 g IV q12h
Pediatric Dose	Not established
Contraindications	Documented hypersensitivity
Interactions	Consumption of alcohol within 72 h may produce disulfiramlike reactions; may increase hypoprothrombinemic effects of anticoagulants; coadministration with potent diuretics (eg, loop diuretics) or aminoglycosides may increase nephrotoxicity
Pregnancy	B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions	Reduce dosage by one half if CrCl is 10-30 mL/min and by three quarters if CrCl <10 mL/min; bacterial or fungal overgrowth of nonsusceptible organisms may occur with prolonged or repeated therapy

Drug Name	Imipenem and cilastatin (Primaxin)
Description	Effective against aerobic and anaerobic gram-negative organisms.
Adult Dose	0.5 g IV q6h
Pediatric Dose	<12 years: Not recommended >12 years: Administer as in adults
Contraindications	Documented hypersensitivity; children <12 y
Interactions	Coadministration with cyclosporine may increase adverse CNS effects of both agents; coadministration with ganciclovir may result in generalized seizures
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studies in humans; may use if benefits outweigh risk to fetus
Precautions	Adjust dose in renal insufficiency; avoid use in children <12 y

Drug Name	Meropenem (Merrem)
Description	Bactericidal broad-spectrum carbapenem antibiotic that inhibits cell-wall synthesis. Effective against most gram-positive and gram-negative bacteria.
Adult Dose	1 g IV q8h
Pediatric Dose	40 mg/kg IV q8h
Contraindications	Documented hypersensitivity
Interactions	Probenecid may inhibit renal excretion of meropenem, increasing meropenem levels
Pregnancy	B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions	Pseudomembranous colitis and thrombocytopenia may occur, requiring immediate discontinuation of medication

FOLLOW-UP

Section 8 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Complications

• Perforation
• Sepsis
• Intra-abdominal abscess
• Death

Prognosis

• If treated early, outcome is generally good.
• If secondary to carcinoma, outcome is dependent on the carcinoma prognosis.

MISCELLANEOUS

Section 9 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Medical/Legal Pitfalls

• Suspect bowel perforation in patients with persistent unexplained tachycardia, fever, or abdominal pain.
• Malignancy should be considered for all patients who present with LBO.

ACKNOWLEDGMENTS

Section 10 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

The authors and editors of eMedicine gratefully acknowledge the contributions of previous author, Charles McCabe, MD, to the development and writing of this article.

MULTIMEDIA

Section 11 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Media file 1:  Large-bowel obstruction. This chest radiograph demonstrates free air under the diaphragm, indicating bowel perforation. Radiograph courtesy of Charles McCabe, MD.
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Media type:  X-RAY

Media file 2:  Abdominal (KUB) film of a patient with obstipation. Dilation of the colon is associated with large-bowel obstruction. Radiograph courtesy of Charles McCabe, MD.
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Media type:  X-RAY

Media file 3:  Large-bowel obstruction. Gastrografin study in a patient with obstipation reveals colonic obstruction at the rectosigmoid level. Radiograph courtesy of Charles McCabe, MD.
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Media type:  X-RAY

Media file 4:  Large-bowel obstruction. Contrast study demonstrates colonic obstruction at the level of the splenic flexure, in this case due to carcinoma. Radiograph courtesy of Charles McCabe, MD.
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Media type:  X-RAY

Media file 5:  Large-bowel obstruction. Abdominal (KUB) radiograph depicting massive dilation of the colon due to a cecal volvulus. Radiograph courtesy of Charles McCabe, MD.
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Media type:  X-RAY

Media file 6:  Large-bowel obstruction. Contrast study of patient with cecal volvulus. The column of contrast ends in a "bird's beak" at the level of the volvulus. Radiograph courtesy of Charles McCabe, MD.
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Media type:  X-RAY

Media file 7:  Large-bowel obstruction. Massive dilation of the colon due to a sigmoid volvulus. Radiograph courtesy of Charles McCabe, MD.
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Media type:  X-RAY

REFERENCES

Section 12 of 12

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

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Article Last Updated: Aug 2, 2007