Differentials
Appendicitis
SIGNS / SYMPTOMS
Typically presents as acute abdominal pain starting in the mid-abdomen and later localising to the right lower quadrant. Associated with fever, anorexia, nausea, vomiting, and elevated neutrophil count.
May be clinically indistinguishable from Meckel's diverticulum.
INVESTIGATIONS
CT scan shows a dilated appendix, and periappendiceal inflammatory changes, such as fat stranding of the mesoappendix or adjacent retroperitoneal fat.[40]
Non-Meckel's diverticulum-related intussusception
SIGNS / SYMPTOMS
Typically presents between 5 and 7 months of age with vomiting; older children also complain of abdominal pain. Often a history of progressive lethargy, and there may have been a recent viral illness.
A palpable abdominal mass or abdominal distention may be found on examination.
May be clinically indistinguishable from Meckel's diverticulum.
INVESTIGATIONS
Plain abdominal x-ray reveals intestinal obstruction and paucity of gas in the right lower quadrant, as well as often showing the characteristic 'target sign'.
Abdominal ultrasound may establish the diagnosis, but contrast enema (air or contrast reagent) is the most specific and sensitive test for diagnosis, and it may be therapeutic.
Biliary colic
SIGNS / SYMPTOMS
Pain and tenderness, usually in the right upper quadrant and sometimes associated with nausea and vomiting.
Pain is most commonly triggered by fatty foods, but it can also be initiated by other types of food, or it can occur spontaneously.
INVESTIGATIONS
Abdominal ultrasound has a high specificity (>98%) for the diagnosis of cholelithiasis and a negative predictive value of 95% for the diagnosis of cholecystitis.[41]
Infectious colitis
SIGNS / SYMPTOMS
Diarrhoea is often present; it may be associated with lower abdominal discomfort or cramps.
May give a history of sick contacts and travel to an area where infectious colitis is endemic.
INVESTIGATIONS
Stool samples are tested for infectious aetiology.
CT scanning is useful to evaluate for thickened, inflamed loops of large bowel.
Colonic diverticulitis
SIGNS / SYMPTOMS
Occurs in adults, mostly >40 years of age.
Lower left quadrant pain, fever, malaise, and leukocytosis.
INVESTIGATIONS
CT scan is the test of choice for symptomatic diverticulitis.
Gastroenteritis
SIGNS / SYMPTOMS
Common in children.
Characterised by nausea, vomiting, and diarrhoea, along with crampy abdominal pain.
Abdominal examination does not identify any localising signs.
INVESTIGATIONS
Clinical diagnosis.
Crohn's disease
SIGNS / SYMPTOMS
Chronic diarrhoea, weight loss, and right lower quadrant abdominal pain mimicking acute appendicitis.
INVESTIGATIONS
Diagnosis confirmed by colonoscopy with ileoscopy and tissue biopsy.[42]
Ulcerative colitis
SIGNS / SYMPTOMS
Typically presents in young adults.
Diarrhoea, often bloody, with faecal urgency and crampy abdominal pain localised to the RLQ or LLQ.
Course may be relapsing-remitting.
May have extraintestinal manifestations, such as erythema nodosum and acute arthropathy.
INVESTIGATIONS
Diagnosis requires, at a minimum, negative stool culture and sigmoidoscopy or colonoscopy.[42]
Tissue biopsy required for confirmation of diagnosis.
Irritable bowel syndrome
SIGNS / SYMPTOMS
Non-specific abdominal pain, bloating, and disturbed defecation.
INVESTIGATIONS
FBC, stool cultures, and colonoscopy exclude organic disease.
Necrotising enterocolitis
SIGNS / SYMPTOMS
Most commonly occurs in premature infants.
INVESTIGATIONS
Abdominal radiographs often demonstrate gas within the intestinal wall (pneumatosis intestinalis).
Peptic ulcer disease
SIGNS / SYMPTOMS
Chronic, upper abdominal pain (often epigastric) related to eating a meal (dyspepsia).
Epigastric tenderness may be present, but often there are no other signs on physical examination.
INVESTIGATIONS
Upper gastrointestinal endoscopy is diagnostic and may show an ulcer in the stomach or proximal duodenum.
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