urinary tract infection (UTI) in children

Last edited 07/2022 and last reviewed 08/2023

• a urinary tract infection is an important diagnosis in a child not to miss because infection may damage the developing kidney
• as with adults, a urinary tract infection in children is defined as more than 10 to the power 5 organisms per ml in voided urine (studies on urine specimens from large numbers of hospital patients confirm that a pure growth of 10^5 organisms per ml or greater is indicative of infection (1)
• about 2% of boys and 8% or more of girls will develop a urinary tract infection during childhood
• UTI is a common bacterial infection that causes illness in babies and children (2)
  • it may be difficult to recognise UTI in children because the presenting symptoms and signs are non-specific, particularly in babies and children younger than 3 years
  • collecting urine and interpreting results is not easy in this age group, so it may not always be possible to unequivocally confirm the diagnosis

Note that in some children, especially boys, the child may not retain urine in the bladder for a long enough period for multiplication to a pure growth of 10^5 organisms per ml to occur. In these cases a pure growth of 10^4-10^5 organisms may indicate infection (3)

NICE state with respect to "Symptoms and signs"(NG224 - urinary tract infection in under 16s: diagnosis and management)

• test the urine of babies, children and young people who have symptoms and signs that increase the likelihood that a urinary tract infection (UTI) is present (see table below and the explanation of how to use the table beneath it).
• consider testing the urine of babies, children and young people if they are unwell and there is a suspicion of a UTI but none of the signs or symptoms listed in table below are present
• refer babies under 3 months with a suspected UTI to paediatric specialist care, and
  • send a urine sample for urgent microscopy and culture
  • immediately refer babies under 3 months with a suspected UTI to a paediatric specialist
    • children whose symptoms or combination of symptoms and signs suggest an immediately life-threatening illness should be referred immediately for emergency medical care by the most appropriate means of transport (usually 999 ambulance)
• do not routinely test the urine of babies, children and young people 3 months and over who have symptoms and signs that suggest an infection other than a UTI. If they remain unwell and there is diagnostic uncertainty, consider urine testing

Table: Symptoms and signs that increase or decrease the likelihood that a UTI is present

When using the table, be aware that:

• The symptoms and signs in this table should be used to inform a decision about whether urine collection and testing is necessary.

• It is not an exhaustive list of symptoms or signs and should be used as a guide alongside clinical judgement.

• The presence or absence of a single symptom or sign in isolation in either column should not necessarily be used to decide whether or not to test for UTI.

• Multiple symptoms and signs will probably increase the likelihood that there is a UTI.

• It may be useful to consider alternative diagnoses where the symptoms and signs decrease the likelihood that a UTI is present.

For babies or children under 5 with fever with no obvious cause where a UTI is no longer suspected, see the NICE guideline on fever in under 5s: assessment and initial management

Avoid delay when collecting and testing the urine sample. If the sample cannot be collected at the consultation, advise the parents or carers (as appropriate) to collect and return the urine sample as soon as possible, ideally within 24 hours.

For detailed guidance then see NICE (July 2022). Urinary tract infection in under 16s: diagnosis and management

NICE now state if suspected UTI is an infants younger than 3 months then (1):

• there are concerns about sepsis in infants under 3 months with suspected UTI, and usual practice is referral rather than the GP managing symptoms. So the committee recommended that all children under 3 months should be referred to specialist paediatric care and have a urine sample sent for urgent microscopy and culture

Notes:

• infants and children presenting with unexplained fever of 38°C or higher should have a urine sample tested within 24 hours (1)
  
  
• infants and children with an alternative site of infection should not have a urine sample tested. When infants and children with an alternative site of infection remain unwell, urine testing should be considered after 24 hours at the latest (1)

Reference:

• NICE (September 2017). Feverish illness in children Assessment and initial management in children younger than 5 years
• NICE (July 2022). Urinary tract infection in under 16s: diagnosis and management
• Prescriber 2000;11 (18): 21-37.