Professor, Dept. of Gastroenterology, AIIMS, New Delhi

A 45-year-old man, a known case of ulcerative colitis (UC) (pancolitis) presented to the emergency with complaints of diarrhea, vomiting, abdominal pain and distension since 4 days.

On examination, the patient appeared pale and dehydrated. Pulse was weak and thready 115/min; blood pressure was 90/60 mmHg and temperature 37.80C. Per abdomen examination revealed distension and tenderness of the lower abdomen, voluntary guarding, but no rebound tenderness; bowel sounds were reduced. There were no other significant findings such as icterus, pedal edema or cyanosis. Blood chemistry revealed hemoglobin (Hb) 5 g/dL, total leukocyte count (TLC) 16,000/mm3, serum sodium 128 mEq/L, erythrocyte sedimentation rate (ESR) 35 mm/hour, serum C-reactive protein (CRP) 62 mg/L, serum potassium 2.9 mEq/L and serum albumin 2.9 g/dL. Anti-tissue transglutaminase (anti-tTG) serology for celiac disease was negative.

Stool samples were negative for ova and parasites. Three sequential stool cultures were negative for any infective pathology. Enzyme immunoassay (EIA) test for Clostridium difficile toxin A and B, was negative.

Plain abdominal X-ray was done, which showed colonic dilatation with dilatation of transverse colon 7 cm confirming the diagnosis of toxic megacolon. Air or fluid levels were also seen. The patient gave a history of severe diarrhea with 8-10 loose stools/day with passage of blood and severe crampy abdominal pain 10 days prior to this. He reported acute weight loss of 1.5 kg. The patient had been on steroid for UC and had stopped taking his medication.

The patient was hospitalized and a nasogastric tube was put in to decompress the gastrointestinal tract. The line of treatment adopted was:

Intravenous (IV) fluids and electrolytes, IV hydrocortisone (100 mg q 6 hours) and broad-spectrum antibiotics. A surgical consultation was also taken and the patient was kept under close observation.

After 48 hours, the abdominal distension had still not improved and so a decision to operate was taken. A subtotal colectomy with end-ileostomy was done. After the postoperative period, patient showed gradual improvement. Patient was given a short course of steroid and then kept in follow-up on sulfasalazine.

Discussion

Severe colitis is defined as 6 or more bloody stools/day plus one sign of systemic toxicity, which includes anemia (<10.5 g/dL), elevated ESR (>30 mm/h), fever (>37.58°C) and tachycardia (90 beats/min).

Diagnosis

Severe UC with toxic megacolon. Fulminant colitis is a critical form of severe colitis and is defined as >10 stools/day, daily continuous bleeding, blood transfusion requirement, elevated ESR (>30 mm/h), fever (>37.58°C), tachycardia (90 beats/min), abdominal tenderness and distension, and colonic dilation on abdominal X-ray.1

Toxic megacolon complicating UC represents an extreme in the spectrum of severe colitis.1 Toxic dilatation is more likely to complicate pancolitis than segmental disease.2 While associated primarily with inflammatory bowel disease (IBD), toxic megacolon is also a documented complication of infectious, ischemic and metabolic insults to the colon.3

Toxic megacolon results from extension of colonic inflammation beyond the mucosa to the underlying tissues, including the muscularis propria. Loss of contractility from the inflammatory reaction leads to the accumulation of gas and fluid within the lumen and subsequent colonic dilatation.4

Bacterial infections of the colon such as C. difficile, Salmonella, Shigella and Campylobacter and viral (cytomegalovirus [CMV]) and parasitic (Entameba) infections may also be complicated by colonic dilatation.5

The main characteristics of toxic megacolon are radiographic evidence of total or segmental colonic distension of >6 cm.5 Maximal colonic dilatation is most commonly observed in the transverse colon.4 In contrast to other types and causes of colonic dilatation like Ogilvie’s syndrome or Hirschsprung’s disease, toxic megacolon is defined by the additional presence of systemic toxicity and the inflammatory or infectious etiology of the underlying disease.5

Diagnosis is made by clinical evaluation for systemic toxicity and imaging studies depicting colonic dilatation. The clinical criteria for diagnosis of toxic megacolon are described in the accompanying Box.5

Plain abdominal imaging is still the most established radiological instrument. Typical features seen in plain abdominal X-rays include dilatation of the colon >6 cm, not rarely up to 15 cm.5

A thorough history is crucial. Knowledge of prior attacks of IBD, the extent and type of disease, details of prior therapy, extraintestinal manifestations of IBD, recent travel, occupational exposure (e.g., day care workers), antibiotic or chemotherapy use, use of antimotility agents and human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) status are very helpful.

Clinical Criteria for Toxic Megacolon5

Main criteria (at least three of the following)

1. Fever (>38.6°C)
2. Tachycardia (>120/min)
3. Leukocytosis (>10.5 x 109/L)
4. Anemia

In addition (at least one of the following)

1. Dehydration
2. Altered level of consciousness
3. Electrolyte imbalances

Stool microscopy and culture should be performed as part of the initial assessment. A test for C. difficile toxin should be performed, because pseudomembranous colitis can complicate or mimic severe UC.6

In the acute setting of toxic megacolon, total colonoscopy has the high-risk of colonic perforation and is therefore generally contraindicated. Limited sigmoidoscopy is considered to be valuable in differentiating etiological causes, for example, to exclude CMV or by identification of pseudomembranes in acute C. difficile colitis.5

Management of toxic megacolon is an interdisciplinary task that requires close interaction of gastroenterologists and surgeons from the very beginning. The main objectives of management are treatment of the underlying cause, attenuation of colitis, treatment of toxemia and circumvention of further complications, specifically bowel perforation. Close medical monitoring and supportive care is imperative.5

Once identified, the management is based on a foundation of supportive measures, bowel rest and decompression.3

Medical therapy is the first-line treatment in most cases.1 But, close clinical observation for signs of impending perforation is critical.4 Daily abdominal radiographs are warranted until the colonic diameter decreases to an acceptable level or an operation is planned. The mainstay of medical therapy for patients with toxic megacolon caused by UC is high-dose IV steroids.

Steroid treatment should be started immediately and not be delayed by pending microbiological results. Most authors recommend a daily dose of either 400 mg hydrocortisone (100 mg every 6 hours) or 60 mg methylprednisolone given IV for about 5 days.5

In general, patients who do not improve after 48-72 hours of medical therapy should undergo surgery.4 But, if the patient should manifest signs of hemorrhage, perforation or peritonitis, surgery is immediately indicated.1

Subtotal/total colectomy and ileostomy is the procedure of choice in most instances and a laparoscopic approach is potentially favored when possible and practical.1

References

1. Strong SA. Management of acute colitis and toxic megacolon. Clin Colon Rectal Surg 2010;23(4):274-84.
2. Sheikh RA, Yasmeen S, Prindivilie T. Toxic megacolon: a review. JK Practitioner 2003;10(3):176-8.
3. McMullen TP, Bailey RJ. Advances in the diagnosis and management of toxic megacolon. Can J Gastroenterol 2005;19(3):163-4.
4. Osterman MT, Lichtenstein GR. Chapter 112. Ulcerative colitis. In: Feldman: Sleisenger and Fordtran’s Gastrointestinal and Liver Disease. 9th edition, Elsevier: Saunders 2011:p.1975-2012.
5. Autenrieth DM, Baumgart DC. Toxic megacolon. Inflamm Bowel Dis 2012;18(3):584-91.
6. Jakobovits SL, Travis SP. Management of acute severe colitis. Br Med Bull 2005;75-76(1):131-44.