eMedicine Specialties > Gastroenterology > Colon

Megacolon, Chronic: Differential Diagnoses & Workup

Author: David M Manuel, MD, Fellow, Department of Internal Medicine, Section of Gastroenterology, Providence Hospital and Medical Center
Coauthor(s): Michael H Piper, MD, FACG, FACP, Clinical Assistant Professor, Department of Internal Medicine, Division of Gastroenterology, Wayne State University School of Medicine; Consulting Staff, Digestive Health Associates PLC; Roberto M Gamarra, MD, Fellow, Department of Internal Medicine, Section of Gastroenterology and Hepatology, Providence Hospital and Medical Center; Clifford Y Ko, MD, MS, MSHS, Department of Surgery, Assistant Professor, University of California at Los Angeles School of Medicine
Contributor Information and Disclosures

Updated: Aug 3, 2007

Differential Diagnoses

Megacolon, Acute
Megacolon, Toxic

Other Problems to Be Considered

Intestinal/colonic obstruction (eg, malignancy, imperforate anus, fecal impaction, rectal prolapse)

Workup

Laboratory Studies

  • Laboratory studies are important to exclude other etiologies, including electrolyte abnormalities (eg, calcium, magnesium, phosphorus).
  • Thyroid function tests should also be performed.

Imaging Studies

  • Abdominal plain films are useful for initial screening and assessment of severity.
  • After plain films reveal the megacolon, water-soluble contrast enema may be helpful for a number of reasons.

    • Accurately assesses the size of the colon
    • Helps to differentiate the presence of megacolon, megarectum, or both
    • Helps to define the anatomy
    • Can be used therapeutically to evacuate the colon
  • Distinguishing a colonic inertia etiology from that of a functional outlet obstruction is probably best accomplished by colonic marker transit studies. Numerous ways to perform this test are available.

    • One method is to instruct the patient to consume 30 g of dietary fiber daily and to stop using laxatives, enemas, and all other nonessential medications for at least 2 days prior to (as well as during) the test.
    • The patient swallows the markers, and abdominal plain films are obtained on days 1, 3, and 5.
    • Patients with colonic inertia tend to have markers distributed throughout the large bowel from cecum to rectum, while patients with outlet obstruction exhibit markers proceeding normally through the colon but accumulating in the rectum.

Other Tests

  • Anorectal manometry may help to distinguish congenital from acquired megacolon.

    • The presence of a rectoanal inhibitory response means that there are intact ganglia, and the patient does not have Hirschsprung disease.
    • If the inhibitory response is absent, a rectal biopsy is still needed to confirm the diagnosis of Hirschsprung disease. 
  • Pudendal nerve latency testing may elucidate problems related to peristaltic movement, anatomical and/or mechanical problems with evacuation, and nerve-associated problems with defecation.

Procedures

  • Colonoscopy should be used to rule out an obstructive/mechanical cause of colonic dilatation.

Histologic Findings

Histology is helpful for determining the etiology of the condition. Although full-thickness biopsy is the criterion standard to establish a diagnosis of Hirschsprung disease, mucosal suction biopsy is adequate in most instances. The absence of ganglion cells is characteristic of Hirschsprung disease, and specific stains for acetylcholinesterase are used to highlight abnormal morphology. Other than Hirschsprung disease, however, the presence of ganglion cells does not specify one cause over another. For most cases, there is no indication for histology because Hirschsprung disease is not considered or excluded by normal manometric findings.

More on Megacolon, Chronic

Overview: Megacolon, Chronic
Differential Diagnoses & Workup: Megacolon, Chronic
Treatment & Medication: Megacolon, Chronic
Follow-up: Megacolon, Chronic
References
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References

  1. Barnes PR, Lennard-Jones JE, Hawley PR, Todd IP. Hirschsprung's disease and idiopathic megacolon in adults and adolescents. Gut. May 1986;27(5):534-41. [Medline].

  2. Camilleri M. Acute and chronic pseudo-obstruction. In: Felman M, Friedman LS, Sleisenger MH, eds. Sleisenger & Fordtran's Gastrointestinal and Liver Disease. 8th ed. Philadelphia: Saunders; 2007:2679-2702.

  3. Camilleri M. Dysmotility of the small intestine and colon. In: Yamada T, ed. Textbook of Gastroenterology. Vol 1. 4th ed. Philadelphia: Lippincott Williams & Wilkins; 2003:1486-1529.

  4. Harari D, Minaker KL. Megacolon in patients with chronic spinal cord injury. Spinal Cord. Jun 2000;38(6):331-9. [Medline].

  5. Krishnamurthy S, Heng Y, Schuffler MD. Chronic intestinal pseudo-obstruction in infants and children caused by diverse abnormalities of the myenteric plexus. Gastroenterology. May 1993;104(5):1398-408. [Medline].

  6. Lane RH, Todd IP. Idiopathic megacolon: a review of 42 cases. Br J Surg. May 1977;64(5):307-10. [Medline].

  7. Metcalf AM, Phillips SF, Zinsmeister AR, MacCarty RL, Beart RW, Wolff BG. Simplified assessment of segmental colonic transit. Gastroenterology. Jan 1987;92(1):40-7. [Medline].

  8. Miyamoto M, Egami K, Maeda S, Ohkawa K, Tanaka N, Uchida E, et al. Hirschsprung's disease in adults: report of a case and review of the literature. J Nippon Med Sch. Apr 2005;72(2):113-20. [Medline].

  9. Nicholls RJ, Kamm MA. Proctocolectomy with restorative ileoanal reservoir for severe idiopathic constipation. Report of two cases. Dis Colon Rectum. Dec 1988;31(12):968-9. [Medline].

  10. Porter NH. Megacolon: A physiological study. Proc R Soc Med. 1961;54:1043.

  11. Preston DM, Lennard-Jones JE, Thomas BM. Towards a radiologic definition of idiopathic megacolon. Gastrointest Radiol. 1985;10(2):167-9. [Medline].

  12. Stabile G, Kamm MA, Hawley PR, Lennard-Jones JE. Colectomy for idiopathic megarectum and megacolon. Gut. Dec 1991;32(12):1538-40. [Medline].

  13. Stryker SJ, Pemberton JH, Zinsmeister AR. Long-term results of ileostomy in older patients. Dis Colon Rectum. Nov 1985;28(11):844-6. [Medline].

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Further Reading

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Keywords

Ogilvie syndrome, pseudo-obstruction, idiopathic megacolon, acquired megacolon, toxic megacolon, colonic inertia, generalized delayed transit, rectosphincteric dyssynergy, functional outlet obstruction, spontaneous perforation, Hirschsprung disease, megarectum, Trypanosoma cruzi, T cruzi, Chagas disease, unrecognized imperforate anus, total abdominal colectomy with ileorectal anastomosis, total proctocolectomy with ileostomy, total proctocolectomy with ileoanal anastomosis

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Contributor Information and Disclosures

Author

David M Manuel, MD, Fellow, Department of Internal Medicine, Section of Gastroenterology, Providence Hospital and Medical Center
David M Manuel, MD is a member of the following medical societies: American College of Gastroenterology, American College of Physicians, American Gastroenterological Association, American Medical Association, American Society of Gastrointestinal Endoscopy, and Crohns and Colitis Foundation of America
Disclosure: Nothing to disclose.

Coauthor(s)

Michael H Piper, MD, FACG, FACP, Clinical Assistant Professor, Department of Internal Medicine, Division of Gastroenterology, Wayne State University School of Medicine; Consulting Staff, Digestive Health Associates PLC
Michael H Piper, MD, FACG, FACP is a member of the following medical societies: Alpha Omega Alpha, American College of Gastroenterology, American College of Physicians, and Michigan State Medical Society
Disclosure: Nothing to disclose.

Roberto M Gamarra, MD, Fellow, Department of Internal Medicine, Section of Gastroenterology and Hepatology, Providence Hospital and Medical Center
Roberto M Gamarra, MD is a member of the following medical societies: American College of Gastroenterology, American College of Physicians, American Gastroenterological Association, American Medical Association, American Society for Gastrointestinal Endoscopy, and Crohns and Colitis Foundation of America
Disclosure: Nothing to disclose.

Clifford Y Ko, MD, MS, MSHS, Department of Surgery, Assistant Professor, University of California at Los Angeles School of Medicine
Clifford Y Ko, MD, MS, MSHS is a member of the following medical societies: American College of Surgeons, American Medical Association, American Society of Colon and Rectal Surgeons, Association for Academic Surgery, California Medical Association, and New York Academy of Sciences
Disclosure: Nothing to disclose.

Medical Editor

Terence David Lewis, MBBS, FRACP, FRCPC, FACP, Program Director, Internal Medicine Residency, & Assistant Chairman, Associate Professor, Department of Internal Medicine, Division of Gastroenterology, Loma Linda University Medical Center
Terence David Lewis, MBBS, FRACP, FRCPC, FACP is a member of the following medical societies: American College of Gastroenterology, American College of Physicians, American Gastroenterological Association, American Medical Association, California Medical Association, Royal College of Physicians and Surgeons of Canada, and Sigma Xi
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Douglas M Heuman, MD, FACP, Director of Hepatology, McGuire Veterans Affairs Medical Center, Professor, Department of Internal Medicine, Division of Gastroenterology, Virginia Commonwealth University School of Medicine
Douglas M Heuman, MD, FACP is a member of the following medical societies: American Association for the Study of Liver Diseases, American College of Physicians, and American Gastroenterological Association
Disclosure: Nothing to disclose.

CME Editor

Alex J Mechaber, MD, FACP, Assistant Dean for Medical Curriculum, Associate Professor of Medicine, Division of General Internal Medicine, University of Miami Miller School of Medicine
Alex J Mechaber, MD, FACP is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians-American Society of Internal Medicine, and Society of General Internal Medicine
Disclosure: Nothing to disclose.

Chief Editor

Julian Katz, MD, Clinical Professor of Medicine, Drexel University College of Medicine; Consulting Staff, Department of Medicine, Section of Gastroenterology and Hepatology, Hospital of the Medical College of Pennsylvania
Julian Katz, MD is a member of the following medical societies: American College of Gastroenterology, American College of Physicians, American Gastroenterological Association, American Geriatrics Society, American Medical Association, American Society for Gastrointestinal Endoscopy, American Society of Law Medicine and Ethics, American Trauma Society, Association of American Medical Colleges, and Physicians for Social Responsibility
Disclosure: Nothing to disclose.

 
 
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