Acute Megacolon Clinical Presentation
- Author: Roberto M Gamarra, MD; Chief Editor: BS Anand, MD more...
The typical patient is an elderly person who is in the hospital, usually for an unrelated reason (eg, recovering postoperatively from surgery), and may or may not already be taking oral feeds.
Orthopedic surgery, cesarean delivery, and cardiovascular or lung surgery are surgeries that commonly predispose to acute megacolon.
Acute megacolon can occur on the medical wards as frequently as on the surgical wards (eg, in patients with unrelated problems, such as pneumonia, sepsis, myocardial infarction, or stroke).
Systemic diseases that affect the neuromuscular component of the GI tract, such as amyloidosis, may first present with an acute episode of pseudo-obstruction.
Not having a history of similar episodes of abdominal distension in the past is common.
Colic-type pain may be present, but the absence of this pain does not imply a less severe condition.
Patients often will experience nausea and vomiting as well as constipation and obstipation.
Physical examination findings may include the following:
- The vital signs can all be normal.
- Depending on the duration of the megacolon and the fluid status, the patient may become tachycardic.
- With distension of the abdomen pushing on the lungs, the patient also may develop tachypnea. In this regard, the lung fields may be decreased.
- The abdominal examination generally reveals a distended abdomen, which may or may not be tense. Serial measurement of abdominal girth is routinely unreliable.
- Bowel sounds vary from absent to diminished to high-pitched, mimicking mechanical obstruction.
- Tympany invariably is present.
- Digital rectal examination should generally be performed to exclude fecal impaction.
Causes of acute megacolon include the following:
- Electrolyte abnormality
- Metabolic abnormality, including hypothyroidism and hyperparathyroidism
- Certain medications, including anticholinergics, antidiarrheals, opiates, digitalis, and certain antipsychotic drugs
- Inflammatory bowel disease, including ulcerative colitis and Crohn colitis
- Infections, including Clostridium difficile (pseudomembranous colitis), Trypanosoma cruzi (Chagas disease), and Entamoeba histolytica (amebic dysentery).
Note that in any setting, a mechanical cause (eg, a tumor) and a toxic cause (eg, acute ulcerative colitis) must be ruled out first because the treatments are very different for these conditions.
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