Refers to the acute obstruction and dilation of the colon in the absence of any mechanical obstruction in severely ill patients.
Colonic pseudo-obstruction is characterized by massive dilatation of the cecum with a diameter of 10 cm or greater noted abdominal X-ray.
May occur after surgical procedures.
Drugs that impair colonic motility, such as anticholinergics or opioid analgesics, contribute to the development of this condition.
The exact mechanism behind the acute colonic pseudo-obstruction is not known, but is presumed to be due to an imbalance in the regulation of colonic motor activity by the autonomic nervous system.
Acute megacolon can lead to ischemic necrosis in massively dilated intestinal segments.
The syndrome may precipitate volvulus.
Patients present with abdominal distention, pain and altered bowel movements, nausea and vomiting.
Treatment is with conservative therapy by stopping oral intake and a nasogastric suction, but may require colonoscopic decompression which is successful in 70% of the cases.
Neostigmine should be considered prior to colonoscopic decompression, butit can induce bradyarrhythmia and bronchospasms.
Mortality rate can be as high as 30%, reflecting that this syndrome is mostly seen in critically ill patients.
The process can also present in otherwise healthy individuals, especially induced by pharmocologic agents with a high mortality rate.