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Toxic megacolon occurs when swelling and inflammation spread to the deeper layers of the colon
Toxic megacolon is a rare and potentially life-threatening complication of severe inflammatory bowel diseases (IBDs) such as ulcerative colitis and Crohn’s disease or infection such as Clostridium difficile colitis.
Toxic megacolon occurs when swelling and inflammation spread to the deeper layers of the colon (the last section of the digestive tract), resulting in widening (dilatation) and decreased functioning of the colon. In severe cases, the colon may rupture. The condition increases the risk of infection throughout the body (sepsis), severe blood loss, shock, dehydration, and sometimes even death.
What causes toxic megacolon?
Toxic megacolon may occur in people with an inflamed colon due to:
- Uncontrolled ulcerative colitis or Crohn’s disease
- Ischemic colitis
- Infections of the colon such as Clostridium difficile
- Infection from a virus, bacterium, or even a parasite (less common):
- Salmonella
- Shigella
- Campylobacter colitis
- Enterohemorrhagic or enteroaggregative Escherichia coli O157
- Entamoeba
- Cytomegalovirus (leading cause of toxic megacolon in people with HIV/AIDS)
What are risk factors for toxic megacolon?
Factors that can increase the risk of toxic megacolon include:
- Hypokalemia (low serum potassium levels)
- Medications (antimotility agents, opiates, anticholinergics and antidepressants)
- Barium enema
- Colonoscopy and bowel preparations
- Ischemia (low blood flow to the colon)
- Colon cancer
Other risk factors include diabetes, organ transplants, kidney failure, suppressed immunity, and chronic obstructive pulmonary disease.
Other types of megacolon do not involve colon inflammation or infection. They include:
- Pseudo-obstruction
- Acute colonic ileus
- Congenital colonic dilation
What are the symptoms of toxic megacolon?
Inflammation of the colon can cause stomach pain, diarrhea, blood in stools, nausea, joint pain, fever, and skin rashes. Signs and symptoms related to toxic megacolon include:
- Abdominal pain, swelling, bloating, and tenderness
- Diarrhea (often serious and bloody)
- Fever
- Rapid heart rate
- Dizziness
- Shock
How is toxic megacolon diagnosed?
Your doctor will examine you and ask about your current symptoms, medical history, and other conditions such as inflammatory bowel disease that tend to inflame the colon. Tests that may be ordered to confirm a diagnosis include:
- Blood tests such as a complete blood count and electrolytes
- X-ray of the abdomen
- Ultrasound
- Computed tomography scan
Diagnostic criteria for toxic megacolon include:
- Radiographic evidence of the dilation of the colon greater than 6 cm
- At least three of the following:
- Fever higher than 100.4 F (38 C)
- Heart rate higher than 120 beats/min
- Neutrophilic leukocytosis exceeding 10,500/micro/L
- Anemia
- At least one of the following:
- Dehydration
- Altered sensorium
- Electrolyte disturbances
- Hypotension
How is toxic megacolon treated?
Toxic megacolon can be deadly if left untreated. Treatment of toxic megacolon may include:
- Medications
- Medications to treat the underlying condition or infection
- Anti-inflammatory medicines and antibiotics to help treat or prevent infection
- Steroids and other immune system suppressants such as infliximab or cyclosporine
- Bowel rest and bowel decompression
- Involves removing gas and substances filling the colon with the help of a suction tube
- Intravenous (IV) fluids
- IV fluids and electrolytes to restore electrolyte levels and prevent dehydration and low blood pressure
- Surgery
- May be required to remove part or all of the colon if less invasive treatments fail to reduce the size of the toxic megacolon within 2-3 days
Your doctor may ask you to stop certain medications that could worsen toxic megacolon including opioids, anticholinergics, antidepressants, and antidiarrheal medications.
What are the complications of toxic megacolon?
Untreated toxic megacolon can result in severe complications such as:
- Bleeding and blood loss
- Generalized infection (sepsis)
- Bowel perforation
- Peritonitis
- Abscess
- Shock
- Abdominal compartment syndrome
The survival rate for well-treated toxic megacolon without perforation is higher than 95%, whereas it is about 80% with perforation.