A dirty cook gives diarrhoea quicker than rhubarb. TUNG-SU PAI (TIME UNCERTAIN)
Diarrhoea is defined as an intestinal disorder characterised by abnormal frequency and liquidity of faecal evacuations.
Acute self-limiting diarrhoea, which is very common and frequently not seen by the medical practitioner, is usually infective and mild, and resolves within days. In Australia most infective cases are viral. The causes of diarrhoea are numerous, thus making a detailed history and examination very important in leading to the diagnosis. ‘Chronic’ diarrhoea is that lasting at least 4–6 weeks. Important causes are presented in FIGURE 34.1.
Important causes of chronic diarrhoea
The terminology for acute infective diarrhoea can be confusing. A simple classification is:
Key facts and checkpoints
The characteristics of the stool provide a useful guide to the site of the bowel disorder.
Disorders of the upper GIT tend to produce diarrhoea stools that are copious, watery or fatty, pale yellow or green.
Colonic disorder tends to produce stools that are small, of variable consistency, brown and may contain blood or mucus.
Acute gastroenteritis should be regarded as a diagnosis of exclusion.
Chronic diarrhoea is more likely to be due to protozoal infection (e.g. amoebiasis, giardiasis or Cryptosporidium) than bacillary dysentery.
Asking about a history of travel, especially to countries at risk of endemic bowel infections, is essential.
Certain antibiotics can cause an overgrowth of Clostridium difficile, which produces pseudomembranous colitis.
Coeliac disease, although a cause of failure to thrive in children, can present at any age.
In disorders of the colon, the patient experiences frequency and urgency but passes only small amounts of faeces.
Diarrhoea can be classified broadly into four types:
A summary of the diagnostic strategy model is presented in TABLE 34.1.
Table 34.1Diarrhoea: diagnostic strategy model ||Download (.pdf) Table 34.1 Diarrhoea: diagnostic strategy model
Serious disorders not to be missed
HIV infection (AIDS)
Inflammatory bowel disease:
Non-microbial food poisoning (e.g. death cap mushroom)
Pelvic appendicitis/pelvic abscess
Pitfalls (often missed)
Faecal impaction with overflow (spurious) diarrhoea
Giardia lamblia infection
Cytomegalovirus in immunocompromised
Malabsorption states (e.g. coeliac disease)
Vitamin C and other oral drugs