Synopsis
Collect and preserve diagnostically useful urine, interpret age-specific bedside testing, and apply the NICE ultrasound, DMSA and MCUG schedules without over-investigating uncomplicated infection.
- Collect urine before antibiotics whenever possible, but never delay treatment of a child at high risk of serious illness.
- First-line collection is clean catch. If impossible, use a manufacturer-approved urine pad; never use cotton wool, gauze or sanitary towels.
- Use catheterisation or ultrasound-guided suprapubic aspiration when a dependable specimen cannot practically be obtained non-invasively.
- Label the collection method and time. Culture within 4 hours or refrigerate immediately; boric acid is an alternative only with correct specimen volume.
- A bag or pad is vulnerable to contamination. Mixed organisms or a result inconsistent with the child should prompt clinical review and often a repeat specimen.
- Urine culture is the reference test for organism and susceptibility; dipstick determines immediate action in children aged at least 3 months.
- Atypical UTI includes serious illness, poor flow, mass, raised creatinine, septicaemia, non-response within 48 hours and non-E. coli infection.
- Recurrent UTI means at least two upper infections, one upper plus at least one lower infection, or at least three lower infections.
- Ultrasound during acute infection is required for atypical UTI at every age and for recurrent UTI under 6 months.
- An infant under 6 months with a first UTI responding within 48 hours receives ultrasound within 6 weeks; an older child generally does not after one uncomplicated responsive infection.
- DMSA at 4–6 months is reserved by age and phenotype: atypical or recurrent infection under 3 years, and recurrent infection from age 3 years.
- MCUG is not routine. It is scheduled for atypical or recurrent UTI under 6 months and considered from 6 months to under 3 years when ultrasound dilatation, poor flow, non-E. coli infection or VUR family history is present.
Key red flags
Serious illness, shock or a young infant under 3 months changes the priority from perfect sampling to immediate specialist sepsis care.
Poor urine flow, abdominal or bladder mass, raised creatinine, septicaemia, non-E. coli growth or non-response within 48 hours makes the infection atypical.
Anuria, a distended bladder, bilateral hydronephrosis, infected obstruction or a solitary obstructed kidney requires urgent urological assessment.
Recurrent UTI meets a specific definition and triggers age-dependent imaging; do not rely on a vague history of unconfirmed infections.
Hypertension, persistent proteinuria, reduced eGFR or bilateral parenchymal defects needs nephrology follow-up rather than simple discharge after imaging.
A specimen left warm for more than 4 hours can overgrow and mislead; refrigerate immediately or use boric acid at the correct sample volume.
Investigation priorities
Provide a non-invasive specimen with the lowest practical contamination risk.
Management branches
Urine is required before antimicrobial treatment.
- Attempt clean catch into a sterile container and document the method and time.
- Use an approved collection pad if clean catch is not possible, following manufacturer instructions and avoiding cotton wool or gauze.
- Use catheterisation or ultrasound-guided suprapubic aspiration when non-invasive collection is impractical and a dependable result is clinically important.