Urine Infections in Babies

When to get help

NHS guidance asks you to get an urgent GP appointment or help from NHS 111 if you think your child may have a urinary tract infection and your child is aged 15 or younger. Age alone puts a child in the urgent category; there is no watch-and-wait tier for children with suspected UTI.

It also asks for urgent advice if symptoms get worse quickly or do not improve within 48 hours of starting treatment, if there is pain in the lower tummy or in the back just under the ribs, or if there is blood in the pee, and notes that some of these could be symptoms of a kidney infection, which can be serious if not treated because it could cause sepsis.

Call 999 or go to A and E if your child is confused, drowsy or has difficulty speaking.

The age threshold in the guideline

NICE guideline NG224 on urinary tract infection in under 16s is explicit for the youngest group. It says to refer babies under 3 months with a suspected UTI to paediatric specialist care, and to send a urine sample for urgent microscopy and culture. A separate recommendation states: immediately refer babies under 3 months with a suspected UTI to a paediatric specialist. NG224 adds that paediatric specialists should give babies under 3 months with a suspected UTI parenteral antibiotics in line with the fever in under 5s guideline, meaning treatment is given by injection or drip rather than by mouth.

For older infants, NG224 says to consider referring babies and children over 3 months with an upper urinary tract infection to a paediatric specialist, and gives antibiotic treatment in line with the relevant NICE prescribing guidance.

Why fever alone triggers a urine test

NICE guideline NG143 on fever in under 5s recommends that children referred to a paediatric specialist with fever without apparent source should have urine tested for urinary tract infection. Urine infection is one of the few treatable causes of an unexplained fever in a baby, and it is invisible without a test.

The American Academy of Pediatrics explains the clinical reality behind that recommendation. It notes that urinary tract infections in infants and young children up to two years of age may have few recognisable signs or symptoms other than a fever, and that they have a greater potential for causing kidney damage than those occurring in older children. It adds that an unexplained high fever, meaning one not explained by a respiratory infection or diarrhoea, may be the only sign of a urinary tract infection in infants, and that if your infant has a fever with no other symptoms for more than three days you should talk with your paediatrician.

NG143 sets the thresholds that govern how quickly a feverish baby is assessed: children younger than 3 months with a temperature of 38C or higher are in a high-risk group for serious illness, and children aged 3 to 6 months with a temperature of 39C or higher are in at least an intermediate-risk group.

Signs in a baby or young child

NHS guidance lists what children with UTIs may have in addition to the general symptoms: a high temperature, with the note that your child is feeling hotter than usual if you touch their neck, back or tummy; appearing generally unwell, with babies and young children being irritable and not feeding, eating or drinking properly; wetting the bed or wetting themselves; and being sick.

The AAP adds that a bladder infection can cause lower abdominal pain, vomiting, tenderness, pain during urination, frequent urination, blood in the urine, recurrence of day or night-time wetting in a previously toilet-trained child, and a low-grade fever, while infection of the kidneys causes more general abdominal pain and a higher fever but may or may not cause frequent and painful urination. It notes that the urine may be cloudy and have a bad odour, and that sometimes there is some blood in the urine.

Smell alone is unreliable. NHS guidance points out that dark or smelly pee can simply mean not drinking enough.

How the sample is collected

Getting urine from a baby is the practical obstacle, and it is worth knowing what to expect. A clean-catch sample, caught in a sterile pot mid-flow after the nappy comes off, is the standard method and is what NG224 assumes. Practices usually supply a pot and may supply a collection pad. Cotton wool balls and squeezing a nappy are not acceptable methods because they contaminate the sample.

Sitting your baby on a towel with the nappy off after a feed, pot ready, is the usual approach, and it takes patience. If a sample cannot be obtained and your baby is unwell, that is a reason to be seen rather than a reason to delay.

Treatment and follow-up

Treatment is with antibiotics chosen and dosed by a clinician, and this page gives no medicine amounts. NHS guidance stresses taking all the medicine prescribed even if your child starts to feel better.

NG224 sets out imaging follow-up after a confirmed infection, with schedules differing for babies under 6 months, children between 6 months and 3 years, and children 3 years or older, and with more testing where the infection was atypical or recurrent. Ultrasound scans and other imaging after a first proven UTI in a baby are routine practice rather than a sign that something serious has been found; the purpose is to check for underlying anatomical causes.

Reducing the chance of it happening again

NHS guidance lists constipation in children among the things that increase the risk of bacteria getting into the bladder, which makes treating constipation a genuine part of prevention. It advises wiping from front to back, keeping the genital area clean and dry, promptly changing nappies or incontinence pads if they are soiled, drinking plenty of fluids, and avoiding scented soap around the genital area. Australia's healthdirect service gives the same advice about hygiene and fluids.

If your child has had two or more infections, ask your GP about referral, because recurrent infection is one of the situations NG224 flags for further investigation.