UTI in children is the most common serious bacterial infection presenting to primary care. Pyelonephritis in young children (especially under 2) causes renal scarring in up to 15% of cases, which can lead to hypertension and CKD in adulthood. Infants under 3 months have immature immune systems — any fever must be treated as serious bacterial infection until proven otherwise. Missing sepsis in a febrile child is the most common paediatric litigation scenario in UK general practice.

Children under 2 rarely have localising urinary symptoms — fever with no focus must trigger UTI exclusion with dipstick and culture. Dipstick alone can guide initial management in older children, but urine culture is essential to confirm diagnosis, guide antibiotic choice, and justify imaging decisions under NICE CG54. Bag specimens have a false positive rate of 85% — never send a bag specimen for culture.

Classification directly determines imaging pathway in NICE CG54. Atypical or recurrent UTIs require USS kidneys, bladder, urinary tract (within 6 weeks) and DMSA scan at 4–6 months (to detect renal scarring). Missing atypical features and failing to image is a common error leading to undetected VUR and progressive renal damage. The RCGP exam frequently tests knowledge of the NICE CG54 imaging schedule.

Examination in children with UTI serves to determine severity (admission vs community management) and identify atypical features that trigger the NICE CG54 imaging pathway. Blood pressure measurement is often omitted but is essential in any child with recurrent UTI — hypertension is a marker of significant renal scarring. Anatomical abnormalities (phimosis, labial adhesions) may be the underlying predisposing factor.

Urine culture before antibiotics is mandatory in children — antibiotic sensitivity data drives treatment in confirmed UTI and imaging decisions in recurrent cases. NICE CG54 imaging decisions are complex and age/UTI type dependent — know the schedule. DMSA detects renal scarring (dimercaptosuccinic acid scan) — the most sensitive marker of upper urinary tract damage. MCUG (micturating cystourethrogram) identifies VUR grades I–V but carries radiation and procedural risk — strictly specialist-led.

Age under 6 months is the key threshold — all UTIs in this group should be discussed with or referred to paediatrics due to the higher risk of structural abnormality, VUR, and renal scarring. The vast majority of school-age children with their first uncomplicated lower UTI can be safely managed in primary care with appropriate safety-netting. NICE CG54 provides a clear framework — deviating from it requires clinical justification.

Trimethoprim resistance in E. coli is rising in the UK (estimated 20–40% in some regions). Always check local antibiogram data from your trust/CCG. Nitrofurantoin is an alternative for lower UTI but is contraindicated in neonates (risk of haemolysis) and those with reduced renal function. 3-day courses for lower UTI are as effective as 7-day courses in children over 2 years and improve adherence. Prophylactic antibiotics are no longer routinely recommended by NICE — reserve for paediatric-led management of VUR.

Constipation is a frequently missed, highly modifiable risk factor for recurrent UTI in children — studies suggest 30–50% of children with recurrent UTI have underlying constipation. Treating constipation alone reduces UTI recurrence significantly. Adequate hydration increases urinary flow rate, reducing bacterial colonisation time. These measures are first-line prevention strategies and often neglected in the rush to prescribe.

Completing the imaging pathway is a GP responsibility — many renal scarring cases in adults are attributable to missed imaging follow-up in childhood UTIs. Renal scarring causes hypertension in up to 10% and contributes to CKD. The GP must ensure the USS and DMSA pathway is coordinated and not lost in hand-off between acute settings and community care. Safety-netting instructions reduce re-presentation delay — parents often wait too long when children deteriorate.