eMedicine Specialties > Gastroenterology > Colon

Megacolon, Chronic: Treatment & Medication

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

Treatment

Medical Care

• In the absence of perforation, initial management is conservative. Some experts believe a role exists for as-needed fecal disimpaction and for evacuation by enemas and suppositories.
• Pay close attention to exclusion of any underlying cause. If identified, correct electrolyte/metabolite abnormalities, and remove medications that may influence colonic motility (eg, narcotics, anticholinergic agents, calcium channel antagonists).
• The use of biofeedback for a colonic inertia etiology for chronic megacolon is probably not effective, although successful treatment of functional outlet obstruction with biofeedback has been reported.
• In patients requiring hospitalization, decompression using nasogastric tubes and rectal tubes may assist in treatment. When such tubes are used, anecdotal experience has demonstrated that frequent position changes for the patient may help to improve decompression.
• If the dilatation persists or worsens, colonoscopic decompression can be attempted, with consideration of placement of a decompression tube, per rectum, to the right side of the colon.
  
  
  • Unfortunately, following decompression, the dilatation usually recurs; therefore, decompression with colonoscopy must be carefully considered, as it is not without risk in an unprepared, dilated colon.
  • Many gastroenterologists no longer consider placement of a drainage tube at the time of colonoscopy, as it nearly always becomes clogged with stool and rapidly ceases to function. 
• Beyond these options for the treatment of acute megacolon, the recommended regimen for chronic megacolon in a stable patient is as follows:
  
  
  • Empty the bowel (eg, osmotic laxatives, enemas, suppositories, cathartics, digital disimpaction).
  • Practice a bowel habit retraining program (eg, scheduled times for defecation, increased physical activity if possible).
  • Consume bulking agents/bowel agents.
  • Slowly alter/individualize the regimen.

Surgical Care

• Surgical care is generally recommended if the dilatation is persisting or worsening after the above medical measures have been exhausted.
  
  
  • Megacolon operative options include total abdominal colectomy with ileorectal anastomosis, total proctocolectomy with ileostomy, and total proctocolectomy with ileoanal anastomosis, depending on the site of the colon affected.
  • Total abdominal colectomy with ileorectal anastomosis is the operation of choice of megacolon with normal-sized rectum.

Consultations

These problems require a multidisciplinary approach, including the primary care provider, a gastroenterologist, a nutritionist/dietitian, and possibly a surgeon.

Diet

Patients with acquired, nonacute megacolon should follow a high-fiber, high-fluid intake diet, which usually helps to decrease constipation. Some patients with severe constipation state that a high-fiber diet produces greater difficulty with bloating and constipation.

Medication

A high water intake is an essential measure. A minimum of 6-8 8-oz glasses a day is recommended.

Bulking agents, through the increase of fiber, are also important. Many agents are on the market for this purpose and typically contain psyllium husk or cellulose; each patient may respond differently to each agent. No single agent is superior to another.

Laxatives may be considered and continued if found to be helpful. The best laxatives for this purpose are osmotic agents, such as magnesium salts, sorbitol, or lactulose (the latter two may increase flatulence). Patients need encouragement to take sufficient amounts to produce a result. Stimulant laxatives are best left as a last resort because they may possibly induce deterioration in the ability of the colon to evacuate. Typical stimulant laxatives are senna and bisacodyl-containing medications. Many patients take natural herbal laxatives; these typically contain cascara.

Tegaserod, a 5HT4 agonist, was approved for use in chronic constipation and in women with constipation-predominant irritable bowel syndrome. Its role in chronic pseudo-obstruction had not been determined.

Laxatives

Increase peristalsis of the intestine, reducing the time toxic substances remain in the lower GI tract.

Psyllium (Metamucil, Fiberall)

Promotes bowel evacuation by forming viscous liquid and perhaps by inducing peristalsis.

Magnesium hydroxide (Philips' Milk of Magnesia)

Causes osmotic retention of fluid, which distends the colon and probably increases peristaltic activity; promotes emptying of bowel.

Sorbitol

Hyperosmotic laxative that has cathartic actions in the GI tract.

Lactulose (Cephulac, Cholac, Constilac)

Produces osmotic effect in colon that results in distention and promotes peristalsis.

Senna (Senexon, Ex-Lax, Senokot, Senna-Gen, Black-Draught, Agoral)

Anthraquinone stimulant hydrolyzed by colonic bacteria into active compound. More potent than cascara sagrada and produces considerably more abdominal pain. Usually produces action 8-12 h after administration.

Bisacodyl (Bisac-Evac, Bisco-Lax, Dulcolax, Dacodyl)

Stimulates peristalsis, possibly by stimulating colonic intramural plexus. Alters water and electrolyte secretion, producing net intestinal fluid accumulation and laxation.

Cascara sagrada

Irritates intestinal mucosa, increasing rate of colonic motility and changes fluid and electrolyte secretion.

Polyethylene glycol (PEG) solution

For treatment of occasional constipation. In theory, less risk of dehydration or electrolyte imbalance with isotonic polyethylene glycol compared with hypertonic sugar solutions. Laxative effect generated because polyethylene glycol is not absorbed and continues to hold water by osmotic action through small bowel and colon, resulting in mechanical cleansing. In theory, less risk of dehydration or electrolyte imbalance with isotonic polyethylene glycol compared with hypertonic sugar solutions. The laxative effect is generated because polyethylene glycol is not absorbed and continues to hold water by osmotic action through the small bowel and the colon, resulting in mechanical cleansing. Supplied with measuring cap marked to contain 17 g of laxative powder when filled to the indicated line. May require 2-4 d (48-96 h) to produce bowel movement.

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