Randomize trial by including patients up to 12 months old in whom a urine sample by a non-sterile method was requested under physician criteria. Intention-to-treat analysis was made.

Urine dipstick was considered as altered if it was positive in leukoesterase test (≥2+) or nitrite test. In patients with an altered urine dipstick, a sterile sample was obtained for culture. If there was an initial altered urine dipstick with a subsequent negative urine culture it was considered as contaminated urine.

Randomised not-blind trial developed between june 1st, 2013 and December 31st, 2014 at the Pediatric Emergency Department (PED) of Rio Hortega Universitary Hospital, a secondary hospital located in Valladolid (Spain).

Participants were infants up to one-year-old in whom a urine sample by a non-sterile method was requested under physician criteria and a written consent was signed by parents/caregivers.

The study obtained the approval of Western Valladolid Review Board.

Exclusion criteria:

Patients were excluded from the study if they met at least one of the following criteria: a) patients in whom a urine sample obtained by sterile method was needed by protocol (i.e. febrile infants less than 3 months old), b) patients with underlying disease unable to oral intake of liquids, c) patients whom parents/caregivers refused to sign the informed consent.

Randomization process:

Patients were assigned to one of the 2 groups of treatment (BS vs. PB) following a 1:1 ratio randomization sequence generated by one of the investigators (RV) using Stata® 12. (Stata Corp, College Station, Texas). After being generated, the sequence was introduced in opaque envelopes sequentially numbered.

Design of the study When, under physician criteria, it was decided to obtain a urine sample by a non-sterile method and the nurse staff that participates in the study were present at the shift, informed consent was asked to parents/caregivers. Once the consent was signed, the nurse opened the corresponding envelope, and the patient was assigned to one of the groups.

For each participant, the nurse that developed the technique filled a spreadsheet with data of the patient. Time was measured by using a stopwatch (the same one for all patients) that was not used for any purpose but the study. Urine sample was sent to the laboratory where one analyst performed the leukocyte-esterase and nitrite test. The analyst has no knowledge about the technique used on each patient and the result of the urine culture was obtained from hospital database.

If urine dipstick result was altered, another urine sample was obtained by sterile method, and urine dipstick and culture was done from that sample. Sterile sample was not routinely obtained from patients in whom non-sterile sample dipstick was normal.

In those patients who were considered as failure, the decision of obtaining an urine sample by the alternative technique, or by urethral catheterization was up to the physician who was attending the patient.

Inclusion Criteria:

• infants up to one-year-old in whom a urine sample by a non-sterile method was requested under physician criteria and a written consent was signed by parents/caregivers.

Exclusion Criteria:

• patients in whom a urine sample obtained by sterile method was needed by protocol (i.e. febrile infants less than 3 months old)
• patients with underlying disease unable to oral intake of liquids
• patients whom parents/caregivers refused to sign the informed consent.