Gastroenteritis and diarrhoea

For the majority, the symptoms are self-limiting and short-lived, explains Dr Anna Cumisky.

Bloody diarrhoea is an important feature to identify as it may herald a colonic carcinoma (Photograph: SPL)
Bloody diarrhoea is an important feature to identify as it may herald a colonic carcinoma (Photograph: SPL)

Gastroenteritis is one of the most common gastrointestinal complaints seen in primary care and can affect all age groups and populations. For the majority, the symptoms are self-limiting, and short-lived and only reassurance is required.

However, there are some important scenarios when more in-depth intervention may be required.

1. Clinical features
Classical features of gastroenteritis are colicky, generalised abdominal pain of acute onset associated with fever, loose bowel motions and nausea and/or vomiting.

The duration of symptoms is normally less than 10 days. The cause is infectious and the pathogen is usually a virus, commonly rotavirus in children.

Bloody diarrhoea is an important feature to identify and may herald a bacterial gastroenteritis or a non-infectious cause, such as inflammatory bowel disease or colonic carcinoma.

History taking should aim to rule out other causes of diarrhoea and look for the potential origin of the illness.

Any recent foreign travel and the current health status of the household should be established and noted.

Examination is important, mainly to assess hydration status and to look for signs of systemic sepsis as well as rule out other causes, in particular a surgical abdomen. Children especially must be thoroughly examined as other pathologies can present with similar symptoms.

Differential diagnosis in adults

Diarrhoea or vomiting but not normally both:

  • Inflammatory bowel disease.
  • Bowel cancer.
  • Irritable bowel syndrome.
  • Constipation with overflow.
  • Addison's disease.
  • Thyrotoxicosis.
  • Carcinoid.
  • Gastritis.
  • Surgical abdomen.

2. Assessment of children

NICE has published written guidance on diarrhoea and vomiting in children under five (CG84). In children, it is generally accepted that vomiting usually lasts one to two days and diarrhoea five to seven days. It is unusual for diarrhoea to persist for more than two weeks.

Although it is not mandatory to see all paediatric patients with presumed gastroenteritis, remote assessment of hydration status should be made.

Points to consider include urine output, colour of skin and warmth of extremities. Irritability or drowsiness suggests a more serious situation.

The threshold for face-to-face assessment should be low and mucous membranes appearance, capillary refill time and peripheral pulses should be noted. A record of heart and respiratory rates and skin turgor should be made alongside assessment for sunken eyes.

Abnormalities of these features are considered red flags.

Abdominal examination in children is particularly important as the commonest differential diagnosis is surgical abdomen.

3. Management
Treatment for gastroenteritis is largely conservative. Rehydration salts, rest and simple analgesia are often all that is required. For some, antispasmodic medication or cautious use of loperamide (in adults only) may be helpful.

Patients should be advised on hygiene measures to reduce transmission, in particular meticulous hand washing.

In persistent cases, or in the case of bloody diarrhoea, diarrhoea following antibiotic treatment or in outbreaks in institutions, stool sample microscopy can be useful to identify a cause. Some pathogens require specific treatment and cases of dysentery and food poisoning require notification.

Children who are dehydrated and unable to tolerate oral rehydration fluids should be considered for admission for IV rehydration. In children, clinical state can deteriorate quicker.

There should be a low threshold for admission of infants, babies who were of low birth weight, children with more than five diarrhoeal stools or two vomiting episodes in the last 24 hours or those who have stopped breastfeeding during their illness.

Some adults also require parenteral fluid rehydration, especially the elderly, those who are immunosuppressed and those with severe infection.

4. Complications
Severe dehydration can result from ongoing profuse diarrhoea even in the absence of vomiting. Untreated, hypovolaemic shock may ensue. The elderly and very young are particularly at risk.

Similarly paralytic ileus as suggested by reduced or absent bowel sounds and a distended abdomen results in poor fluid absorption and early parenteral fluid support is required.

Extension of infection can occur, particularly with salmonella infection which can invade the meninges, gall bladder, joints and bones. A more rare complication is Guillain-Barre, which can follow both campylobacter and viral gastroenteritis.

Haemolyticuraemic syndrome (HUS) represents the triad of acute renal failure, microangiopathic haemolytic anaemia and thrombocytopenia and most commonly occurs in children, following an Escherichia coli diarrhoeal illness.

Passage of blood in the stool should alert a GP to consider HUS. Oligouria or haematuria may be present.

The condition can also be associated with severe bowel infarction, rhabdomyolysis and a reduction in conscious level.

Although treatment is largely supportive, it is usually undertaken in a tertiary centre as dialysis may be required and the course of the illness may be complicated by respiratory or cardiac failure or pancreatitis.

5. Contraceptive advice
Women using oral contraceptives must be advised of the risk of poor medication absorption and recommended to use alternative precautions for the duration of illness and for seven days afterwards.

  • Dr Cumisky is a locum GP in Bath, Avon
Differential diagnosis in Children
  • Sepsis (for example, urinary tract, chest, ears, meninges as origin).
  • Coeliac disease.
  • Surgical abdomen (in particular appendicitis, intussusception, pyloric stenosis).
  • Mesenteric adenitis.
  • Diabetic ketoacidosis.
  • Thyrotoxicosis.
  • Addison's disease.
  • Regurgitation (especially in babies).


Red flags
  • Bloody diarrhoea.
  • Young children/infants.
  • Signs of dehydration.
  • Marked localised abdominal pain - consider a surgical cause.
  • Recent antibiotic treatment.
  • Nocturnal diarrhoea.
  • Comorbidities, for example, diarrhoea or immunosuppression.

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