Differentials
Bacterial gastroenteritis
SIGNS / SYMPTOMS
Often clinically indistinguishable.
Features suggestive of a bacterial aetiology include fever >39°C (>102.2°F), bloody diarrhoea, significant abdominal tenderness, and toxicity.
INVESTIGATIONS
Presence of faecal leukocytes.
Three fresh stool samples should be collected on different days and sent for microscopical examination for culture. A positive stool culture confirms the diagnosis.
Protozoal gastroenteritis
SIGNS / SYMPTOMS
Protozoal parasites such as Giardia intestinalis, Entamoeba histolytica, and Dientamoeba fragilis are uncommon causes of gastroenteritis, but are more likely if diarrhoea lasts >14 days and the child has been to an endemic area.
The onset is usually insidious and the course is chronic.
There may be multi-system involvement and weight loss.
INVESTIGATIONS
Presence of ova, cysts, and parasites on stool microscopy. Three fresh stool samples should be collected on different days.
Food poisoning
SIGNS / SYMPTOMS
Food poisoning results from ingestion of food containing preformed toxins produced by bacterial contaminants.
Presenting symptoms include profuse vomiting and abdominal cramps. There is often a history of similar illness in those people who ate with the patient. Onset of symptoms within a few hours suggests staphylococcal food poisoning whereas onset between 24 and 48 hours suggests salmonellosis.
INVESTIGATIONS
Stool specimen positive for culture or presence of specific toxin.
Antibiotic-associated diarrhoea
SIGNS / SYMPTOMS
History of antibiotic use.
Approximately 10% to 15% of children who are given antibiotic treatment develop diarrhoea that is often self-limited and dose related.
INVESTIGATIONS
Clinical diagnosis.
Pseudomembranous colitis
SIGNS / SYMPTOMS
History of antibiotics such as clindamycin, amoxicillin/clavulanate, and second- and third-generation cephalosporins in particular predispose to overgrowth of Clostridium difficile and development of pseudomembranous colitis.
Affected patients often present with explosive watery diarrhoea, fever, vomiting, abdominal cramps, and tenesmus.
INVESTIGATIONS
Stool culture positive for C difficile or enzyme immunoassay (EIA) for its toxins.
Intussusception
SIGNS / SYMPTOMS
Colicky abdominal pain, vomiting, and passage of 'redcurrant-jelly' stool.
The pathognomonic sign is an elongated mass in the right upper quadrant or epigastrium with a feeling of emptiness in the right lower quadrant (Dance's sign).
INVESTIGATIONS
Plain abdominal x-rays may show dilated loop of intestine, air-fluid levels, paucity of air in the right lower quadrant, and a soft mass in the right or mid abdomen.
Abdominal ultrasonography may show a tubular mass ('sandwich' or 'pseudokidney' sign) in longitudinal views and a target appearance ('doughnut' sign) in transverse views.
Acute appendicitis
SIGNS / SYMPTOMS
Usually presents with nausea, vomiting, fever, and right lower quadrant pain at McBurney's point.
Pathognomonic signs include localised tenderness and rebound tenderness.
Diarrhoea is characteristically absent.
INVESTIGATIONS
WBC shows leukocytosis and a differential count shows a predominance of polymorphonuclear cells.
If doubt exists, the diagnosis can be confirmed by abdominal ultrasound or CT scan, which may show an oedematous, distended, and non-compressible appendix.
Coeliac disease
SIGNS / SYMPTOMS
The onset of the disease coincides with the introduction of gluten into the diet.
Typically presents with diarrhoea, vomiting, irritability, wasting, abdominal distension, and faltering growth.
Stools are characteristically foul smelling, pale, loose, bulky, and frothy.
INVESTIGATIONS
The antitissue transglutaminase IgA antibody test is highly sensitive and specific.
Proximal small bowel biopsy shows villous atrophy.
Cystic fibrosis
SIGNS / SYMPTOMS
There may be a positive family history of cystic fibrosis or history of meconium ileus or meconium plug syndrome in the neonatal period.
Clinical features include chronic diarrhoea, recurrent respiratory infections, faltering growth, abdominal distension, nasal polyps, and digital clubbing.
Stools are bulky, greasy, and offensive.
INVESTIGATIONS
Sweat chloride test shows a chloride content of ≥60 mmol/L (≥60 mEq/L).
Crohn's disease
SIGNS / SYMPTOMS
Chronic intermittent diarrhoea, urgency to defecate, abdominal cramps, rectal bleeding, anorexia, aphthous ulcers, peri-anal fistula, and peri-anal abscess.
Extra-intestinal manifestations include faltering growth, pubertal delay, digital clubbing, intermittent pyrexia, arthritis, erythema nodosum, anaemia, renal stones, gallstones, and episcleritis.
The onset is insidious.
INVESTIGATIONS
Colonoscopy with intubation of the ileum may show inflammatory changes, ulcers, nodularity, and strictures.
Biopsy of the involved bowel may show non-caseating granulomas.
Ulcerative colitis
SIGNS / SYMPTOMS
Chronic bloody diarrhoea, tenesmus, urgency, and abdominal pain.
The onset is insidious and nocturnal diarrhoea is characteristic.
Extra-intestinal manifestations include faltering growth, pyoderma gangrenosum, sclerosing cholangitis, chronic active hepatitis, and ankylosing spondylitis.
INVESTIGATIONS
Colonoscopy may show micro-ulcers, erythema, oedema, and friability of the mucosa.
Biopsy of the involved bowel shows mucosal inflammation.
Use of this content is subject to our disclaimer