Haemolytic Uraemic Syndrome (HUS) is the commonest cause of intrinsic renal acute kidney injury in children in Scotland. In most cases, it follows infection with shigatoxin producing Escheriae Coli (E.Coli), the commonest subtype being 0157:H7. In most patients, there is a preceding history of diarrhoea which is frequently bloody. 10-15% of patients will progress to develop HUS, with children <16 years (in particular patients <5 years) at highest risk.
Haemolytic Uraemic Syndrome refers to a triad of findings which include:
- Microangiopathic Haemolytic Anaemia
- Red cell fragmentation on Blood Film
- Acute Kidney injury
Acute bloody diarrhoea should be treated as a medical emergency and requires urgent action. Patients in primary care should be referred for urgent same day paediatric assessment and triaged at minimum category 3. All patients will require paediatric assessment and bloods and urinalysis at first assessment.
The incubation period of E.Coli is typically 3-4 days however may be as long as 14 days. The mean onset of HUS to develop after initial diarrhoea is 7 days. Normal blood results during the diarrhoeal phase do not exclude HUS and it is important to take a clear history of onset of diarrhoea for risk assessment.
Figure 1: Timeline of STEC-HUS: Days from ingestion to symptoms12
HUS most commonly follows a diarrhoeal prodrome but may also occur after infections with other organisms such as S. Pneumoniae, or from other aetiologies such as drugs, pregnancy or may be familial. These other forms of HUS are mentioned in Section 7
Criteria for entry
Criteria for entry into the pathway for Bloody Diarrhoea or suspected E.Coli are:
- Acute bloody diarrhoea
- Minimum of one episode of blood in stool AND
- Diarrhoea defined as acute onset loose stool
- Non bloody acute diarrhoea AND suspicion of Coli
- Contact with
- farm animals
- contaminated environments (fields, farms, rural areas)
- Untreated water from rivers or private supplies
- A known or suspected case of E.Coli
- Contaminated food (undercooked meat, unpasteurised milk, raw vegetables)
- Travel out with the UK
- An outbreak of Coli is known to be present locally or nationally
- Contact with
Other causes of blood in stools should always be considered, including surgical causes.
Patients with blood in stools who should NOT directly enter the pathway unless specific concerns of exposure to E.Coli include:
- Infants and children with suspected cow’s milk protein intolerance
- Patients with suspected or confirmed inflammatory bowel disease
- Patients with blood coated stool secondary to constipation, including those with overflow diarrhoea
It is recommended all patients with blood in the stool have stool cultures sent to exclude E.coli