Toxic megacolon shows itself most of the time when your colon becomes infected, irritated, or inflamed for some reason that we may not know. The colon is the last part of the digestive tract. By itself, it does not mean you would be diagnosed with toxic megacolon. It is suspicious however if your colon has expanded or dilated wider than it would normally. It will begin to make the poisonous substances in your stool push throughout your body, which is called systemic toxicity. You must get immediate medical attention as it can cause tears in the colon, loss of blood or even a deadly illness referred to as sepsis when your body starts to become inflamed as the toxins start to hit your major organs causing them to shut down one by one.
You have probably heard of someone having toxic megacolon. Patients are miserable with this illness. Sometimes it is called toxic colitis, but it will rear its ugly head with severe episodes of the colitis along with sections of the colon or the entire colon dilating and looking very large on x-ray. Most of the time, it seems to be a complication of someone who has ulcerative colitis. Still, there are other times it could be coming from an exacerbation from someone with Chrohn’s disease, pseudomembranous colitis brought on by antibiotics or other colitides.
If you look at toxic megacolon pathologically, the acute fulminant colitis can be accompanied by neuromuscular degeneration with rapid as well as extensive dilatation of the patient’s colon.
You will notice that most patients come to the emergency room with toxic megacolon showing up with their abdomen being very distended with acute or chronic diarrhea. Toxic megacolon should always be included as a possible diagnosis with these patients. To diagnose, it takes a thorough clinical history with a physical exam and plain abdominal x-rays.
When x-rays are viewed, the transverse colon will often be identified because it is so dilated in the anterosuperior position. It will also be found that the diameter of the colon has increased to more than 6 cm, causing the physician to be highly suspicious of toxic megacolon.
The images themselves may present with an irregular, coarse mucosal look in the large bowel that some call thumbprinting. It seems to be caused by edema of the mucosa because of the inflammation that has infiltrated. A CT will help identify the extent of inflammation, abscesses, and ascites. Other than that, Ultrasound and radionuclide studies are of little help.
Hirschsprung disease, intestinal pseudo-obstruction, or Chagas disease might resemble the toxic megacolon with plain x-rays. But, since this will occur in different settings medically, it is unlikely that they would get confused with anyone that had toxic megacolon.