Differentials
Asthma
SIGNS / SYMPTOMS
Patients present with repeated episodes of coughing, wheezing, chest tightness, and dyspnoea. There may be an identifiable trigger (e.g., tobacco smoke, certain animals, or exercise).
INVESTIGATIONS
Diagnosis is confirmed using pulmonary function tests (PFTs). CXR may be normal or may show evidence of underlying infection.
Viral gastroenteritis
SIGNS / SYMPTOMS
Self-limiting watery diarrhoea, vomiting, or both, with or without fever, malaise, and anorexia, are common presenting symptoms. Diarrhoea and vomiting are less common in ascariasis.
INVESTIGATIONS
It is not usually necessary to perform stool examinations on patients with viral gastroenteritis. However, a stool sample should be obtained if there is an outbreak, to identify the pathogen as quickly as possible. Stool culture is the most definitive diagnostic test in identification of viral pathogens, but this is not practical in most cases. Latex agglutination tests, polymerase chain reaction (PCR), microscopy, enzyme immunoassay (EIA), or serology allows rapid detection, but these are usually not necessary.
Amoebiasis
SIGNS / SYMPTOMS
Usual presentation is with diarrhoea that lasts several days, abdominal pain, and weight loss. If there is hepatic infection, then jaundice, RUQ pain, and hepatomegaly may also be present.
INVESTIGATIONS
Patients with amoebiasis may have stool ova and parasites positive for characteristic trophozoites or cysts, or a positive serological test for Entamoeba histolytica.
Salmonella infection
SIGNS / SYMPTOMS
Presents with nausea, vomiting, and diarrhoea. The patient may also complain of headaches, abdominal pain, fever, or myalgia. There may be history of the patient eating contaminated food (e.g., undercooked eggs or meat).
INVESTIGATIONS
Stool or blood culture may grow Salmonella.
Strongyloides infection
SIGNS / SYMPTOMS
Presents with abdominal pain, diarrhoea or constipation, weight loss, skin changes such as dermatitis or pruritus, and pulmonary complaints such as wheezing or coughing.
There may be a history of travel to an endemic country (e.g., many tropical and sub-tropical regions worldwide, Appalachian region of the US, and certain Mediterranean regions, especially Catalonia, Spain).
INVESTIGATIONS
Patients with strongyloidiasis may have larvae in stool or sputum, or a positive serology test for S stercoralis.
Pancreatitis
SIGNS / SYMPTOMS
Abdominal pain is usually severe, epigastric, and radiating towards the back. It is usually accompanied by fever, nausea, and vomiting. There may also be voluntary abdominal guarding and mild abdominal rigidity with rebound tenderness.
INVESTIGATIONS
Raised serum amylase and lipase are key to diagnosis.
Cholecystitis
SIGNS / SYMPTOMS
Presents with RUQ pain, nausea, and a positive Murphy's sign. There may be a history of previous similar episodes or of known gallstones.
INVESTIGATIONS
Ultrasound of RUQ may show pericholecystic fluid, distended gallbladder, thickened gallbladder wall, or gallstones.
Acute appendicitis
SIGNS / SYMPTOMS
Typically presents with constant mid-abdominal pain that moves to the RLQ. Pain worse on movement. Anorexia, nausea, and low-grade fever are common.
INVESTIGATIONS
Diagnosis is usually clinical. However, an FBC could show mild leukocytosis. Further investigations, such as abdominal ultrasound or CT, are indicated in atypical presentations.
Ancylostomiasis
SIGNS / SYMPTOMS
Patients with heavy hookworm infections (Ancylostoma duodenale or Necator americanus) may develop a cough characteristic of Loeffler's syndrome.
A patient may occasionally become host to A caninum or A braziliense, the dog and cat hookworms, and may also develop a cough characteristic of Loeffler's syndrome. Examination also reveals itchy red papules consistent with a creeping eruption associated with this infection. As larvae migrate through the skin, pruritic serpiginous tracks are formed.
INVESTIGATIONS
Stool studies may demonstrate hookworm eggs.
Eggs are not noted in stool studies in patients who are host to the dog or cat hookworm.
Patients with hookworm infection may demonstrate hypochromic microcytic anaemia on FBC.
Trichuriasis
SIGNS / SYMPTOMS
Also called whipworm infection. May present with abdominal pain, bloody diarrhoea, and tenesmus. Chronic infection can lead to Trichuris trichiura colitis, which is similar to inflammatory bowel disease.
INVESTIGATIONS
Stool studies reveal characteristic eggs. Anoscopy may also demonstrate worms on visualisation of the rectum.
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