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Acute abdominal pain in a child with inflammatory bowel disease

BMJ 2013; 346 doi: http://dx.doi.org/10.1136/bmj.f563 (Published 14 February 2013) Cite this as: BMJ 2013;346:f563
  1. F L Cameron, paediatric registrar in gastroenterology, hepatology, and nutrition1,
  2. L Armstrong, consultant paediatrician2,
  3. E Stenhouse, consultant paediatric radiologist3,
  4. C Davis, consultant paediatric surgeon4,
  5. R K Russell, consultant in paediatric gastroenterology, hepatology, and nutrition1
  1. 1Department of Paediatric Gastroenterology, Hepatology and Nutrition, Yorkhill, Royal, Hospital for Sick Children, Glasgow G3 8SJ, UK
  2. 2Department of Paediatrics, Crosshouse Hospital, Kilmarnock, UK
  3. 3Department of Paediatric Radiology, Yorkhill, Royal Hospital for Sick Children, Glasgow, UK
  4. 4Department of Paediatric Surgery, Yorkhill, Royal Hospital for Sick Children, Glasgow, UK
  1. Correspondence to: F L Cameron fcameron{at}doctors.org.uk

A 10 year old girl with inflammatory bowel disease presented with a two week history of eight to 10 bloody diarrhoeal stools a day, abdominal pain, and lethargy. She had been started on oral prednisolone four days before admission. On admission, her inflammatory markers were raised, with a C reactive protein 312 mg/L (reference value <3; 1 mg/L=9.52 nmol/L), white blood cell count 30×109/L (4-10), albumin 34 g/L (35-45), and haemoglobin 104 g/L (110-160). On examination she was unwell, with a heart rate of 140 beats/min, blood pressure of 100/70 mm Hg, and temperature of 38.2°C. She was cool peripherally, with a capillary refill time of three to four seconds, and her abdomen was soft but generally tender. Her paediatric ulcerative colitis activity index (PUCAI) score was 65 (≥65 defines severe disease). She underwent plain abdominal radiography (fig 1).

Questions

  • 1 What is the diagnosis and what features on the radiograph point to it?

  • 2 What management strategies should be used here?

  • 3 What risk factors and infections should be excluded?

  • 4 What is the long term prognosis?

Answers

1 What features are seen in this radiograph and what is the diagnosis?

Short answer

The radiograph shows abnormal colonic dilation, particularly in the transverse colon, with loss of normal haustration and thumbprinting, indicative of mucosal oedema (fig 2). Mild central dilation of the small bowel is also present, but no evidence of perforation. The diagnosis is toxic megacolon complicating a case of acute severe colitis. A colonic diameter of greater than 56 mm, together with systemic toxicity, is diagnostic in children over the age of 10.1

Figure2

Fig 2 Plain abdominal radiograph showing abnormal colonic dilation (double headed white arrow), loss of normal haustration, and thumbprinting indicating mucosal oedema within the colon (two single headed white arrows) in a child with inflammatory bowel disease and a toxic megacolon

Long answer

Although it may be difficult to distinguish between severe colitis and early toxic megacolon on plain radiography, a transverse colon diameter of greater than 56 mm is strongly suggestive of toxic megacolon in children over 10 years.1 In younger children, the cut-off point is 40 mm.2 Multiple air fluid levels in the colon are common, and deep mucosal ulcerations may appear as air filled crevices between large pseudopolypoid projections that extend into the colonic lumen. Sometimes mucosal islands representing oedematous remnants of mucosa can be seen. The patient’s clinical condition is more important than the absolute width of the colonic segment. No perforation is apparent in this case.

Toxic megacolon is a rare and potentially fatal complication of inflammatory bowel disease or infectious colitis and is characterised by total or segmental non-obstructive colonic dilation plus systemic toxicity. The systemic toxicity distinguishes it from other causes of colonic dilation, such as Hirschsprung’s disease or acquired megacolon resulting from chronic constipation.3 The incidence of toxic megacolon has decreased in recent years owing to early recognition and management of severe colitis, but the lifetime risk in patients with Crohn’s disease and ulcerative colitis is 1-5 %.4

Symptoms of acute colitis, often resistant to treatment, are usually present for a week before the start of acute dilation, usually with bloody diarrhoea. The paediatric ulcerative colitis activity index (PUCAI) has recently been devised and validated for use in children with ulcerative colitis. A score of 65 or more defines severe disease.2 The score is calculated on the basis of symptoms, does not require invasive tests, and can be used to monitor disease activity on a regular basis. PUCAI can be calculated on admission and at days 3 and 5. In acute severe colitis, this information can be used to predict response and the need to move to secondline treatment.5 6 However, its use is limited in toxic megacolon because children are extremely unwell and delay in colectomy may result in increased morbidity and even death.

Current criteria for the diagnosis of toxic megacolon are evidence of systemic toxicity plus fever (>38°C), tachycardia, dehydration, electrolyte disturbance, hypotension or shock, and altered level of consciousness. In children, hypotension and altered level of consciousness are often absent, with fever, tachycardia, dehydration, and electrolyte imbalance being more common in toxic megacolon than in acute severe colitis.1 5 In adults, the criteria include radiological evidence of toxic megacolon, and at least three of the following: fever (>38°C), heart rate more than 120 beats/min, anaemia, and neutrophils greater than 10.5×109/L plus either dehydration, altered consciousness, electrolyte disturbance, or hypotension.7 Patients may or may not show signs of localised or generalised peritonitis. Importantly, signs and symptoms of toxic megacolon may be masked in patients on high doses of steroids or analgesics who also have impaired sensory perception.2 7 Ultimately, it is a clinical-radiological syndrome and radiographic appearances must be considered along with the clinical picture.

2 What management strategies should be used here?

Short answer

Intravenous corticosteroids, broad spectrum intravenous antibiotics, and prompt surgical review, with close monitoring of clinical and blood parameters.

Long answer

Management strategies should combine aggressive treatment with close observation to reduce the chance of acute perforation. In the past, acute severe colitis in children carried a mortality of 1%, mainly as a result of perforation, toxic dilation, and infection.8 Mortality rates in adults were higher because older age and other comorbidities are important risk factors.9 In a more recent study in a cohort of 10 children with toxic megacolon, seven had undergone colectomy by discharge but none had died.1 This suggests that previous mortality rates are outdated and have probably improved with advances in management. Acute severe colitis is more common than toxic megacolon, with a reported incidence in children of one per 100 000 population per year in a North American cohort.2

The first step in management is administration of intravenous steroids which, in adults, reduce mortality from 24% to 7%.5 10 11 Evidence on the use of antibiotics in this setting is controversial.8 However, in areas of high C difficile infection,12 in children whose condition is severe enough to necessitate admission, given the general safety of antibiotics and the high failure rate of standard medical treatment, it would not be unreasonable to use antibiotics if the clinician thought that they were clinically indicated. Patients should be placed on a nil by mouth regimen to decompress the gastrointestinal tract and allow the gut to rest. Stools should be sent for culture, sensitivity, and C difficile toxin. Prompt surgical review is indicated, and if the patient is not improving or clinically deteriorates, surgery should be performed with subtotal colectomy and end ileostomy the procedure of choice. Electrolytes should be regularly checked because they can become deranged owing to the inflamed colon losing its capacity to reabsorb salt and water; potassium loss may also increase as a result of inflammatory diarrhoea.3 Erythrocyte sedimentation rate and C reactive protein are usually raised. Albumin is usually low because of protein loss and reduced hepatic synthesis as a result of chronic inflammation and malnutrition.3 If the diagnosis of inflammatory bowel disease has not yet been made a limited sigmoidoscopy may be performed to aid diagnosis.3 A full colonoscopy should not be undertaken because of the increased risk of bowel perforation.3

3 What risk factors and infections should be excluded?

Short answer

Potential predisposing factors for toxic megacolon include hypokalaemia and use of opioids, loperamide, anticholinergics, psyllium seeds, and antidepressants. The cessation or rapid reduction of corticosteroids, sulfasalazine, or mesalazine may also contribute.3 Clostridium difficile infection is another possible risk factor to exclude. It is increasingly common in adults and children and can be easily treated.

Long answer

Infection with C difficile is an important risk factor for toxic megacolon in children with inflammatory bowel disease, especially those who are immunocompromised or have renal or liver failure.13 A recent study showed that 25% of children admitted with inflammatory bowel disease had C difficile infection, compared with 9% of controls without inflammatory bowel disease.14 In adults with inflammatory bowel disease, C difficile increases hospital admission and mortality rates, with reported mortality of 4.2% in those with C difficile compared with 0.5% in those with inflammatory bowel disease.15 Only about 50% of adults are diagnosed using a single stool sample assayed for C difficile toxins, so current recommendations state that four to five stools should be screened before infection can be excluded in high risk patients.5

Toxic megacolon can also occur in patients without inflammatory bowel disease, often as a result of infection with salmonella, shigella, campylobacter, or HIV. Cytomegalovirus is the leading identified cause of toxic megacolon and emergency laparotomy.16 In inflammatory bowel disease, cytomegalovirus identified by immunohistochemistry on intestinal biopsies is thought to be the most clinically significant risk factor for toxic megacolon. A sigmoidoscopy should be performed in children with steroid resistant disease to exclude cytomegalovirus infection in children with acute severe colitis.5 If biopsies are positive, appropriate antiviral treatment should be started.

4 What is the long term prognosis?

Short answer

In one study, 70% of children with toxic megacolon needed colectomy compared with 30% of controls with acute severe colitis without toxic megacolon.1

Long answer

Meta-analysis of outcomes in acute severe colitis in paediatrics showed that corticosteroids had a 34% failure rate.2 8 In the past, patients with inflammatory bowel disease were at highest risk of developing toxic megacolon early in their disease.7 The cause of this in unknown but is hypothesised to be related to delayed diagnosis, although this was not confirmed in recent studies. Adults who survive toxic megacolon with medical management have a worse prognosis than children, with 47-57% requiring a colectomy at follow-up.17 However, since these data were published management and drugs have improved.

Patient outcome

Our patient was initially managed with intravenous antibiotics, corticosteroids, and fluid resuscitation. When she presented to our centre she was clinically shocked, so despite initial medical management she underwent a colectomy and ileostomy formation.

Notes

Cite this as: BMJ 2013;346:f563

Footnotes

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

  • Provenance and peer review: Not commissioned; externally peer reviewed.

  • Patient consent obtained.

References