Acute Megacolon Treatment & Management

Updated: Oct 31, 2016
  • Author: Roberto M Gamarra, MD; Chief Editor: BS Anand, MD  more...
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Medical Care

Conservative management is preferred when the patient is clinically stable. Consider the following:

  • The underlying cause is treated, if possible, such as correction of any electrolyte/metabolic abnormalities and removal of medications that may decrease colonic motility (eg, narcotics, anticholinergic agents, calcium channel antagonists).
  • Oral feeding should be discontinued, and intravenous fluids should be initiated.
  • If nausea and vomiting are present, nasogastric decompression should be initiated.


Use of a rectal tube

Decompression using a rectal tube may assist in the treatment only if the sigmoid colon is involved. When such tubes are used, anecdotal experience has demonstrated that frequent position changes for the patient may help improve decompression. Complications with these rectal tubes include tube obstruction and colonic/rectal ulceration.

Colonoscopic decompression

If the dilatation persists or worsens, colonoscopic decompression with or without placement of a tube in the right colon should be considered. Although the placement of a decompression tube per rectum is generally suggested, some experts believe that the tube often becomes obstructed with stool and ceases to work after a short time. Randomized controlled trials of the efficacy of colonoscopic decompression are lacking. The resolution of ileus, perforation, and mortality rates are similar between endoscopic and conservative management.


Neostigmine (adrenergic antagonist) has been demonstrated in noncontrolled and controlled studies to improve acute colonic megacolon. Whether a trial of neostigmine should be performed before or after colonoscopic decompression is unclear.

The major indication for its use is failure of conservative therapy after 72 hours. Failure of conservative therapy is generally defined by a cecal diameter of greater than 9 cm.

Contraindications include bradycardia, systolic blood pressure of less than 90 mm Hg, active bronchospasm, serum creatinine level of greater than 3 mg/dL, and evidence of bowel perforation.

Adverse events include abdominal cramping (17%), excessive salivation (13%), transient bradycardia (6%), diaphoresis (4%), and nausea and vomiting (4%). Based on expert opinion, a starting dose of 1 mg may reduce the likelihood of bradycardia.

Cardiac monitoring of patients during treatment with neostigmine is generally recommended, and atropine should be at the bedside.

A second dose of neostigmine should be considered if there is a partial or minimal response to the initial administration.

Of note, although neostigmine often induces clinical decompression, this decompression has not been shown to reduce perforation and mortality rates.


The urgency of management often depends on the size of the colon and the rate of change of the cecal diameter. Some experts believe that regardless of the criteria used for defining acute megacolon, the diameter of the cecum is the most important criterion because the cecum is generally the area that perforates. While the diameter at which the cecum perforates is variable, expert experience indicates that the cecum rarely perforates at a diameter of less than 12 cm.



Once relieved, close follow-up care, including physical examination and maintenance of a normal electrolyte balance, is important.

Avoid using agents that slow transit time, such as opiates and anticholinergics.

Diet and activity

Most patients are in the hospital when acute pseudo-obstruction is diagnosed, and bowel rest should be instituted. Parenteral nutrition may be considered depending on the patient's nutritional status.

Because many of the cases of acute pseudo-obstruction occur postoperatively, the patients tend to be already at bed rest. Remembering to continue prophylaxis for deep venous thrombosis, per the individual physician's protocol, is important; however, if the patient is not severely ill, is not in severe pain, and is stable to ambulate, no reason exists for the patient to remain in bed.


Surgical Care

In view of the high rate of recurrence of colonic dilation following medical and endoscopic therapies, other therapeutic modalities have been proposed.

Percutaneous cecostomy may successfully allow for colonic decompression, but complications with this procedure are high.

Surgical options include cecostomy, colostomy, or colectomy, although surgical therapies are associated with even poorer outcomes. A colectomy is indicated if perforation or colonic ischemia is present. [5]