Why does the collection method matter?
Urine is sterile in the kidney, but on its way out it can be contaminated by bacteria on the skin and genitals. In a sample that is not collected correctly, bacteria are “found” and the child gets unnecessary antibiotics, or the opposite happens and a real infection is missed.
In children who use the toilet
- Hands are washed.
- The genitals are washed with water; soap and antiseptic are not needed. In girls, front to back; in boys, with the foreskin gently pulled back.
- The child starts to pass urine, and the first part goes into the toilet.
- The middle part is collected in a sterile container.
- The rest goes into the toilet again.
In babies
- “Clean catch” method: 30–60 minutes after a feed, the diaper is opened, the genitals are washed and a sterile container is held ready. Lightly tapping the baby’s lower belly and lower back stimulates passing urine.
- Catheter sample: in urgent cases and in small babies, by a health care worker.
- Urine bag: a bag stuck to the skin. It is easy, but the sample gets contaminated quickly. A negative result almost rules out infection, while a positive result must be repeated using a correct method.
Delivering the sample
- The sample should reach the laboratory within 1–2 hours.
- If delayed, it can be kept in the refrigerator (4°C) for up to 24 hours.
- Write the child’s name, the date and the time on the container.
Before antibiotics
When a urinary tract infection is suspected, the sample must be collected before starting antibiotics. Even a single dose of antibiotic can make the culture result falsely negative.
Note for pediatricians and family doctors
A positive culture from a bag-collected sample is unreliable for diagnosis because of its high false-positive rate; a positive screening result should be confirmed with a midstream, catheter or suprapubic aspiration sample. In infants, stimulation methods such as Quick-Wee are useful for a 'clean catch'. Thresholds for significant bacteriuria on culture depend on the collection method.
What happens at the visit?
- When needed, the sample is collected at the clinic using the correct method.
- Urinalysis and culture results are assessed together with the symptoms.
Frequently asked questions
The test shows white blood cells. Is this an infection?
Not always. White blood cells are a sign of inflammation, but in girls they can also come from outside contamination, fever or other causes. The diagnosis is made from the symptoms and the culture of a correctly collected sample.
When will the culture result be ready?
Usually in 2–3 days. That is why, in a child with fever, antibiotics are started without waiting for the culture result and are adjusted later based on the result.
Related topics
Sources
- EAU Guidelines on Paediatric Urology, 2025: Urinary tract infections.
- Kaufman J et al. Faster clean catch urine collection (Quick-Wee method) from infants: randomised controlled trial. BMJ, 2017.
This page is for education. Decisions about your child’s treatment are made together with the doctor after an examination.