• Urinary Tract Infection (UTI) must be considered and investigated for in any febrile child without any obvious cause for the fever.
  • Infant under 3 months of age, who presents with signs and symptoms of UTI, is ‘High Risk’ for serious illness and must be referred to the paediatric department in the hospital for management.
  • It is useful to send the urine for culture and sensitivity if there is a strong suspicion of UTI. The usual method of choice for urine collection in children is a Clean Catch sample; ‘Quick Wee’ method could be used in infants.
  • It is important to differentiate between Upper UTI (Pyelonephritis) and lower UTI (cystitis) as the treatment duration is different for each diagnosis (10 days versus 3 days respectively).
  • Significant Pyuria is > 10 x 106 /L of urine; confirmed UTI on culture is a pure growth > 105  Colony forming units (CFU)/mL on a clean catch urine sample. Lower count acceptable if pyuria is significant and clinical symptoms present.
  • If treating with antibiotics, review child at 48 hours to ascertain clinical improvement and correlate with the urine culture and sensitivity results. Do not routinely repeat urine test after treatment if the child clinically improves.
  • Avoid Ibuprofen in children who are dehydrated or known to have underlying renal abnormalities.
  • Recurrent UTI is often due to a functional/ structural abnormality of the urinary tract. Constipation is frequently associated as a cause of recurrent UTI.
  • If requesting renal ultrasound in the continent child- please ask for pre and post void volumes as well as evaluating the bladder function.
  • Review the need for continuing prophylactic antibiotics every 6 months and stop it if no UTIs in the last 6 months, unless a specialist advises otherwise, usually due to existing, structural renal anomalies.
  • Ensure parents receive adequate information about encouraging their child to have good local hygiene, plenty of oral fluids (such that urine is almost colourless), take measures to prevent constipation, recognise signs and symptoms of UTI; know how to collect urine and seek medical help promptly.
  • Infants under 6 months of age need further imaging after a single, febrile UTI (DMSA/MCUG) if the renal ultrasound is abnormal, atypical bacteria on urine culture or poor response to the correct antibiotics in 48 hours.
  • MCUG is invasive but is the gold standard test for grading VUR. MAG3 is preferred in continent children when screening for presence of VUR.

Consider doing blood tests (FBC, Urea, Electrolytes, Creatinine, Bicarbonate, Liver Function Tests, Calcium, Magnesium, Phosphate, Urate) for renal function when child gets a cannula for DMSA/MAG3. 

The following advice is mainly based on NICE guidance (CG54 with updates in 2018), supplemented by comments from the Scottish Paediatric Renal Group and caters to the needs of both primary and secondary care.

Early diagnosis and treatment of UTI in children is important as infection can damage the developing kidney.

Clinical Signs / Symptoms of UTI in Children

  • Infants and children with unexplained fever of 38°C or higher should have a urine sample tested within 24 hours.
  • Infants and children with an alternative site of infection should not routinely have a urine sample tested. If they remain unwell beyond 24 hours of initiating treatment/management, urine testing should be considered.

Age Group

Symptoms and Signs

                             More Common             ----->                  Less Common                                 


Under 3months


Lethargy/ Irritability

Poor feeding
Failure to thrive

Abdominal pain
Offensive urine

Infants and children 3 months and over



Abdominal pain
Loin tenderness
Poor feeding

Lethargy/ Irritability
Offensive urine*
Failure to thrive



Dysfunctional voiding
Changes to continence
Abdominal pain
Loin tenderness

Offensive/cloudy urine

*Offensive urine may be also be due to dehydration or co-existing constipation.

Assess:The level of illness (Green - low risk, Amber - intermediate risk, Red - High Risk) in infants and young children in accordance with NICE guideline on Fever in Under 5s.

Consider Underlying Serious Pathology



Poor urine flow (particularly for boys)*

High risk/serious illness suspected

Previous UTI

Age under 3months*

Antenatally diagnosed renal anomaly

Enlarged Bladder*

Family history of vesicoureteric reflux (VUR) or renal disease

Abdominal Mass*


Poor Growth

Dysfunctional Voiding

Evidence of Spinal Lesion*

Recurrent fever of uncertain origin

High Blood Pressure* (Box 1 below)

* Urgent referral to paediatrics, on-call registrar, via 01463 704000 (Raigmore Hospital switchboard)

BOX 1: Average systolic blood pressures by age (rough guide)

Age (years)

Average Systolic Blood Pressure

1 to 2

80 to 95

2 to 5

80 to 100

5 to 12

90 to 110

Over 12

100 to 120

Reference: The Hands-on Guide to Practical Paediatrics, First Edition. Rebecca Hewitson and Caroline Fertleman. © 2014 John Wiley & Sons, Ltd. and APLS 6e

Definitions of UTI (BOX 2)

Upper UTI /Pyelonephritis

  Lower UTI/cystitis

Recurrent UTI

Atypical UTI

  • Fever: 38°C or over
  • Lethargy
  • General Malaise
  • Vomiting
  • Loin Pain
  • Non specific abdominal Pain
  • Frequency Urgency
  • Dysuria
  • Enuresis
  • Frank Haematuria

TWO Upper UTI within 12 months       
ONE Upper UTI + ONE lower UTI within 12 months
THREE or more lower UTI within 12 months

*Seriously ill
*Poor urine flow
*Abdominal or bladder mass
*Raised creatinine
*Septicaemia (fluid bolus + IV antibiotics)
*Failure to respond to appropriate antibiotics in 48 hrs 
*Infection with non-E.coli organisms.

  • Uncomplicated UTI (a terminology used sometimes): UTI in patients who have a normal, unobstructed genitourinary tract, no history of recent instrumentation and symptoms are confined to the lower urinary tract.

Urine collection - core principles.

  • A clean catch urine sample is the recommended method for urine collection in infants and young children (non-toilet trained) and a mid-stream urine in an older child. Cleaning genitalia with water, prior to urine collection, is required.
  • In infants, there is some evidence for the “Quick-Wee method” (fig. 1) for clean catch urine collection. It involves gentle, suprapubic, cutaneous stimulation using a gauze soaked in cold fluid for 5 minutes, which might significantly hasten bladder voiding in infants 1 to 12 months of age. Needless to say, before doing this, it is essential to be ready with a sterile bowl to catch the voided urine!
  • Fig. 1 Quick-Wee method: 

  • If a clean catch urine sample is unobtainable, non-invasive methods such as urine collection pads may be used, strictly following the manufacturer’s instructions. DO NOT use urine bags, cotton wool or gauze due to high risk of contamination.
  • Urine samples should preferably be taken prior to starting antibiotics.
  • If symptoms and signs highly suggestive of UTI and/or dipstick positive for leucocytes and/or nitrites, the urine should be sent for microscopy and culture.
    Note: Nitrites might be falsely negative in young infants and children who are not toilet trained as urine does not sit long in the bladder to form nitrites.
  • In a severely unwell infant/ child, treatment should not be delayed if the urine sample is unobtainable.
  • Urine samples for microscopy and culture should be collected in a red-top urine container (contains boric acid) and care taken to prevent overfilling (can destroy bacteria and cause false negative results). Ensure lid is replaced tightly (can leak and will not be processed).
Box 3: Urine Dipstick for diagnosis: (L = leucocyte esterase, N = Nitrites)


Urine for microscopy and culture?

Start Antibiotic?

L+ N+



L- N+



L+ N-


3 years and under - Yes (if symptoms specific for UTI)
Over 3 years - await urine culture

L- N-


No (unless strong suspicion of UTI/risk factors*)

*See Box 5
Leukocyte esterase positive on dipstick may be indicative of an infection outside the urinary tract in a febrile child which may need to be managed differently.

 Box 4: Interpretation or Urine Microscopy results in conjunction with culture
Microscopy results Pyuria positive Pyuria negative
Bacteriuria positive The infant or child should be regarded as having UTI The infant or child should be regarded as having UTI
Bacteriuria negative Antibiotic treatment should be started if clinically UTI The infant or child should be regarded as not having UTI
  • Significant Pyuria > 10 x 106 /L of urine; Bacteriuria is often referred to the bacteria on microscopy or on culture.

Urine Culture criteria for diagnosis:

  • Urine culture is easier to interpret when urine sample is taken before antibiotics. 
  • Confirmed UTI = Significant growth = pure growth >105Colony forming units (CFU)/ml. Any growth on a urine from suprapubic aspirate is significant.
  • Do NOT routinely repeat urine culture after finishing antibiotics, if the child has clinically improved.
  • Do NOT [test urine (!) and] treat Asymptomatic Bacteriuria
Box 5. Urine samples should be sent for culture:
  • Suspicion of acute pyelonephritis/upper UTI
  • High to intermediate risk of serious illness/ Infants under 3 months
  • In infants and children under 3 years: positive leukocyte esterase only (but specific signs of UTI present).
  • High suspicion of UTI and/or underlying renal abnormality.**
  • In infants and children with recurrent UTI.
  • In infants and children with an infection that does not respond to treatment within 24 to 48 hours, if no sample has already been sent
  • When clinical symptoms and dipstick tests do not correlate.

$$: Non-Ecoli pathogens may not induce significant pyuria. If high clinical suspicion of UTI, urine for culture must be sent and chased for definitive diagnosis.

Blood Tests:Full blood count, Urea, Electrolytes, Creatinine, Bicarbonate, Liver function tests, Calcium, Magnesium, Phosphate, CRP.

C-reactive protein alone should not be used to differentiate acute pyelonephritis/upper urinary tract infection from cystitis/lower urinary tract infection in infants and children.

Acute management

Self-Care: General principles:
  • Advise the parents/ carers to bring the child for reassessment if no response to treatment within 24 to 48 hours. 
  • Advise drinking adequate fluids (such that urine is nearly colourless) to avoid dehydration or if vomiting/severely unwell, may need IV fluids.
  • Paracetamol is safe for analgesia and if needed, could consider addition of codeine for children over 12 years. Avoid ibuprofen (can use cautiously with adequate hydration and no known underlying renal abnormality).
  • Advise that children who have had a UTI should have ready access to clean toilets in school when required and should not be expected to delay voiding (a letter to school may be needed). 
  • Ensure that they are aware of the possibility of a UTI recurring and the need to seek prompt treatment from a healthcare professional should this occur. 
  • Explore and correct constipation, avoid bubble baths and tight synthetic underwear.
  • Ensure correct wiping (front to back) after passing urine and complete emptying of bladder (double voiding, knees apart in girls especially if enuresis is present).
  • In young boys the foreskin may be a source of infection and this area should be kept clean.
Antimicrobial Prescribing:  General Principles:
  • Offer an antibiotic (if indicated) after sending urine for culture and sensitivities, if possible.
  • Advise about its side effects of diarrhoea and nausea.
  • When prescribing, oral route should be first choice for antibiotic administration. Exceptions: under 3 months of age, vomiting/severely ill child (will need IV antibiotics).
  • Remember to check for any underlying serious renal pathology, previous urine cultures and sensitivities which may have led to resistant bacteria.
  • Do not increase dose of prophylactic antibiotic (if child is on it). Start alternative antibiotic and discontinue the original prophylactic antibiotic.
  • Use narrow spectrum antibiotic wherever possible.
  • Review antibiotics at 48 hours. Consider switching from IV to oral if afebrile for 24 hours and clinically better. Change and/or add antibiotic if still unwell, based on urine culture and sensitivities.
Pyelonephritis/ Upper UTI: Antimicrobial Prescribing (See BNFc for doses)
  • Trimethoprim may not be appropriate as the first choice of antibiotic if a diagnosis of pyelonephritis/Upper UTI is made.
  • Nitrofurantoin is not suitable for treatment of pyelonephritis as it does not reach therapeutic concentrations in the kidney.
  • Total Duration of treatment is 10 days (oral/IV+oral)
  • Remember to review patient & urine culture, sensitivities at 48 hours; change antibiotic if no clinical improvement.



Antibiotics of choice

Under 3 months / High risk of serious illness

Urgent referral to paediatrics

IV antibiotics
Cefotaxime + Amoxicillin

3 months and over

Consider referral to paediatrics based on clinical assessment

Oral: 1st choice

IV Ceftriaxone

Oral: 2nd choice
Co-amoxiclav (if culture available and susceptible)


+ Gentamicin*

*Aminoglycosides (gentamicin) may be added if susceptibility/sepsis is a concern and/or fever not subsiding after 48 hours. Drug levels need to be monitored; ensure duration is 5 to 7 days only.

**Check previous isolates. If ESBL or multiresistant isolates including enterococcus; contact microbiologist for advice.

Use higher dose of Cefalexin, ie. 25mg/kg/dose

Warn parents about side effect of diarrhoea when prescribing co-amoxiclav.

Lower UTI/ Cystitis: Antimicrobial Prescribing (check BNFc for doses)
  • Wherever possible, send urine for microscopy and culture before starting antibiotics.
  • Total duration of antibiotics: 3 days (remember to review/change antibiotic if no improvement in 48 hours).
Children aged 3 months and over:
First choice
Trimethoprim if low risk of resistance
Nitrofurantoin if eGFR 45mL/minute or greater Narrow spectrum.  Oral suspension very expensive.  Can colour urine yellow/brown.

Children aged 3 months and over: 
Second choice
Worsening lower UTI symptoms on first choice taken for at least 48 hours or when first choice not suitable.

Nitrofurantoin if eGFR 45mL/minute or greater and not first choice
Amoxicillin (only if culture results available and susceptible)
Cefalexin Broad spectrum
Management of Recurrent UTI  (includes antibiotic prophylaxis)
  • Refer children and young people with recurrent UTI to a paediatric specialist for assessment and investigations.
  • Recurrent UTI is often due to a functional/ structural abnormality of the urinary tract. Constipation may often be associated.
  • There is insufficient evidence for effectiveness of antibiotic prophylaxis in reducing the risk of recurrent UTI/development or progression of renal scarring in children.
  • However, antibiotic prophylaxis may be considered in children and young people under 16 years who have recurrent UTI, after treatment of current UTI but only under specialist advice when other management options (behavioural and personal hygiene) have been unsuccessful.
  • Choice of antibiotic should be based on previous urine sensitivities, low risk of complications and patient preference.
  • Risk of resistance and adverse effects of long-term antibiotics should be clearly explained to parents/carers.
  • It is essential to base the decision for antibiotic prophylaxis on an assessment of underlying causes, taking into account the severity and frequency of previous symptoms and the risk of developing complications.
  • Consider antibiotic prophylaxis at birth based on recommendations in antenatally detected, congenital renal anomalies guideline and liaise with paediatric surgeon/urologist as advised in the guideline: https://www.clinicalguidelines.scot.nhs.uk/ggc-paediatric-guidelines/ggc-guidelines/neonatology/renal-anomalies-detected-or-suspected-antenatally/
  • Choice of antibiotics:

1st choice:  Trimethoprim or nitrofurantoin: Children on nitrofurantoin prophylaxis should be monitored for liver function and pulmonary symptoms.

2nd choice: Cefalexin or *amoxicillin (*off-label, not licensed for prevention of UTI)

  • Review antibiotic prophylaxis every 6 months with an aim to stop if no urine infections in the last 6 months. For children needing prophylaxis for longer durations, specialist teams may discuss using different antibiotic every 6 months on a rotational basis, to prevent resistance.
  • If antibiotic prophylaxis is stopped, ensure that the parents are aware of what symptoms and signs suggestive of UTI to look out for and have rapid access to treatment.
  • Emphasise that this approach is not curative and they should still seek medical assessment if there are symptoms of UTI.
  • Reiterate the principles of self-care at every review to reinforce strategies to prevent UTI.
  • In addition, ensure parents
    • Promptly recognise the signs and symptoms of UTI
    • Are aware about correct method of urine collection
    • Have a spare red-top urine container and sterile bowl for collection if they have concerns about urine infection and submit this swiftly for preventing delay in diagnosis and management.
    • Understand the importance of completing treatment regimes and if on prophylaxis- to be compliant.
    • Are aware of the side-effects of the prescribed antibiotics and what to do if they develop.
    • Understand all treatment options as well as the nature and reason of any urinary tract investigation.

Referral to secondary care

Decisions regarding imaging

Important considerations & Interpretations:
  • Renal ultrasound in the continent child should always be requested with pre and post void urine volumes. This is vital for the assessment of the bladder.
  • Renal ultrasound cannot conclusively rule out renal scarring.
  • If requesting a DMSA/MAG3, please consider blood tests at the time of cannulation (complete request forms) for FBC, U&E, Bicarbonate, LFTs, Calcium, Magnesium, Phosphate, urate, checking weight, height, blood pressure, urine protein:creatinine ratio and document them on ward attender sheet.
  • MCUG and/or DMSA should only be considered when the UTI was considered “upper” UTI (ie. associated with fever: 38°C or greater, symptoms of UTI and bacteriuria and especially if abnormal renal ultrasound).
  • DMSA is not recommended after a single febrile UTI if typical bacteria, clinical response within 48 hours of treatment and a normal renal ultrasound.
  • DMSA findings are especially significant when the difference in relative function of the kidneys is greater than 10%.
  • If atypical UTI but no systemic symptoms including fever are present and/or, not a recurrent UTI and normal renal ultrasound- do not do a DMSA/MCUG.
  • Diagnosis of permanent scars is better at 6 months as opposed to 4 months after an UTI. If UTI occurs again before DMSA is done, consider doing the DMSA earlier (will need a special request to Nuclear Medicine Consultant at Raigmore usually via an email).
  • MCUG should usually be considered only if Renal ultrasound and/or DMSA is abnormal. MAG3 may be preferable when screening for VUR in continent or older children as they can void on demand.
  • On requesting MCUG:A3 day treatment course of antibiotics (usually trimethoprim unless resistant- then use other alternative antibiotic) is prescribed when MCUG is arranged with the MCUG taking place on the 2nd day of the treatment course. There is a template in Renal folder on intranet to post out to parents.
  • Plain X-ray abdomen is rarely indicated. It may be requested by specialist colleagues when assessing for renal/ureteric stones.
  • MRU (Magnetic resonance Urography) may be occasionally requested by specialist colleagues.
Recommended imaging schedule for infants younger than 6 months
Test Responds well to treatment within 48 hours Atypical UTI (a) Recurrent UTI (a)
Ultrasound during the acute infection No Yes (c) Yes
Ultrasound within 6 weeks Yes (b) No No
DMSA 4-6 months following the acute infection No Yes Yes
MCUG No Yes Yes

a - see box 1 for definition
b - If abnormal consider MCUG
c - In an infant or child with non-E.coli-UTI, responding well to antibiotics and with no other features of atypical infection, the ultrasound can be requested on a non-urgent basis to take place within 6 weeks

Recommended imaging schedule for infants and children 6 months or older but younger than 3 years

Test Responds well to treatment within 48 hours Atypical UTI (a) Recurrent UTI (a)
Ultrasound during the acute infection No Yes (c) No
Ultrasound within 6 weeks No No Yes
DMSA 4-6 months following the acute infection No Yes Yes
MCUG No No (b) No (b)

a - see box 1 for definition
b - While MCUG should not be performed routinely it should be considered if the following features are present:

  • dilation on ultrasound
  • poor urine flow
  • non-E. coli-infection
  • family history of VUR

c - In an infant or child with non-E.coli-UTI, responding well to antibiotics and with no other features of atypical infection, the ultrasound can be requested on a non-urgent basis to take place within 6 weeks

Recommended imaging schedule for children 3 years or older

Test Responds well to treatment within 48 hours Atypical UTI (a) Recurrent UTI (a)
Ultrasound during the acute infection No Yes (b) (c) No
Ultrasound within 6 weeks No No Yes (b)
DMSA 4-6 months following the acute infection No No Yes

a - see box 1 for definition
b - Ultrasound in toilet-trained children should be performed with a full bladder with an estimate of bladder volume before and after micturition.
c - In an infant or child with non-E.coli-UTI, responding well to antibiotics and with no other features of atypical infection, the ultrasound can be requested on a non-urgent basis to take place within 6 weeks


  • After the first UTI:  no routine follow-up if all the imaging is normal. It should be agreed with parents/carers that the results would be communicated to the parents in writing.
  • Infants and children who have recurrent UTI or abnormal imaging results should be assessed by a paediatric specialist. There should be emphasis on self-care in all appointments.
  • Infants and children who have bilateral renal abnormalities, impaired kidney function, raised blood pressure and/or proteinuria should receive monitoring and appropriate management by a paediatric nephrologist/paediatrician with renal interest, to slow the progression of chronic kidney disease.
  • Assessment of infants and children with renal parenchymal defects should include height, weight, blood pressure and routine testing of early morning urine for proteinuria. Be aware of age, gender and height centile based BP charts for children.

2016 European Society of Hypertension guidelines for the Classification of hypertension in children and adolescents.

Category 0-15 years
SBP and/or DBP percentile
16 years and older
SPB and/or DBP percentile
Normal Less than 90th <130/85
High-normal More than 90th and less than 95th 130-139/85-89
Hypertension More than 95th more than 140/90
Stage 1 hypertension 95th to 99th and 5mmHg 140-159/90-99
Stage 2 hypertension More than 99th plus 5mmHg 160-179/100-109

2016 European Society of Hypertension guidelines for the management of high blood pressure in children and adolescents.  Lurbe et al. J Hypertens 34:1887–1920.

BP charts in children (boys and girls)


Patient Information Resources

Author contacts

Specialty Doctor in Paediatrics with Renal Interest: Dr Janaki Vedarajan- Contact via secretary or email- janaki.vedarajan@nhs.scot

Paediatric Renal Secretary: Paula Graham, Raigmore Hospital- 01463 701342 (from outside the hospital). Extension 7542 (from within the hospital). Mon-Fri 9-5pm

Last reviewed: 30/08/2020

Next review date: 30/08/2024

Author(s): UTI in children working group.

Version: 6

Approved By: TAM subgroup of ADTC

Reviewer name(s): Janaki Vedarajan, Specialty Doctor in Paediatrics.

Document Id: TAM509