What is toxic megacolon?

From the Guidelines

Toxic megacolon is a medical emergency that requires immediate hospitalization and a multidisciplinary approach with gastroenterologists and surgeons, with surgery being mandatory in patients presenting with complications such as perforation, massive bleeding, clinical deterioration, and signs of shock, as well as in those showing no clinical improvement and biological signs of deterioration after 24–48 h of medical treatment, as stated in the WSES-AAST guidelines 1.

Initial Management

Initial management of toxic megacolon includes:

• Bowel rest (nothing by mouth)
• Intravenous fluids for rehydration
• Broad-spectrum antibiotics, typically a combination of metronidazole 500mg IV every 8 hours plus a third-generation cephalosporin like ceftriaxone 1-2g IV daily
• Nasogastric tube decompression may be necessary
• Corticosteroids, such as hydrocortisone 100mg IV every 8 hours, are often used if inflammatory bowel disease is the underlying cause

Monitoring and Surgery

Close monitoring of vital signs, abdominal examinations, and serial abdominal X-rays is essential.

• If no improvement occurs within 24-72 hours or if perforation develops, emergency colectomy is indicated, as supported by the WSES-AAST guidelines 1.
• The condition most commonly results from severe inflammatory bowel disease (particularly ulcerative colitis), but can also occur with Clostridioides difficile infection, other infectious colitis, or ischemic colitis.
• The pathophysiology involves severe inflammation leading to paralysis of colonic smooth muscle, resulting in dilation and potential perforation.
• Early recognition and aggressive treatment are crucial to prevent mortality, which can reach 20-30% even with optimal management, highlighting the importance of prompt surgical intervention in complicated cases, as recommended by the WSES-AAST guidelines 1.

From the Research

Definition and Characteristics of Megacolon Toxico

• Megacolon toxico, also known as toxic megacolon, is a fatal complication of inflammatory bowel disease (IBD) or any infectious etiology of the colon, characterized by total or partial nonobstructive colonic dilatation and systemic toxicity 2, 3.
• The main characteristics of toxic megacolon are toxemia, sepsis, and distension of the colon due to diminished muscular tone, loss of motor activity, and increased amount of colonic gas 4.
• Toxic megacolon is associated with high morbidity and mortality, and surgical management is necessary for the majority of cases 2, 3.

Diagnostic Procedures

• The most important diagnostic procedure is the abdominal X-ray, which can confirm the diagnosis of toxic megacolon if the diameter of colonic distension exceeds 60 mm 4.
• Other diagnostic procedures include plain radiographs of the abdomen, sigmoidoscopy, and awareness of the condition 2.
• Computed tomography scanning and transabdominal intestinal ultrasound are also promising alternatives that add additional information 5.

Management and Treatment

• Conservative treatment of toxic megacolon consists of water and electrolyte replacement, total parenteral nutrition, administration of corticosteroids and broad-spectrum antibiotics, and repeat patient's prone positioning 4.
• If medical therapy is not successful during the first 72 hours, surgical intervention is indicated, with the most common procedure being subtotal colonic resection with creation of an ileostomy 4, 6.
• The optimal timing of surgery for toxic megacolon can be challenging and requires close interaction of gastroenterologists and surgeons from the very beginning 5.
• Patients with toxic megacolon should be managed at specialized centers, where cooperation of experienced gastroenterologists, surgeons, and intensive care experts is possible 4.

Complications and Associated Conditions

• Toxic megacolon can be complicated by massive hemorrhage, perforation, or peritonitis, which may require emergency surgical intervention 2, 3.
• Patients with inflammatory bowel disease are particularly prone to infectious complications, and therapy for these inflammatory diseases is based on the use of immunosuppressive drugs and frequent abdominal surgeries 3.
• Toxic megacolon can also be associated with other conditions, such as ischemic colitis, collagenous colitis, or obstructive colorectal cancer 5.