Recently, a nurse-led randomized controlled trial was conducted in the Stanford Health Care Emergency Department and published in the Journal of Emergency Nursing in September 2019. The abstract of the publication is outlined in the following article.

Stanford Health Care – Research Publication

A nurse-led randomized control trial was used to examine whether urine culture contamination could be reduced by using silver colloidal wipes and a funnel collection designed for the clean-catch midstream urine collection. A 2×2 factorial design was used as this method allows researchers to efficiently test two interventions in one study simultaneously.


The idea for this study came from Edward “Ed” Shradar in 2014 when he was the Clinical Nurse Specialist (CNS) in the Stanford Emergency Department (ED). Ed wanted to investigate novel methods to lower the rate of contaminated midstream clean-catch urine culture samples in the ED. Despite various quality improvement and education initiatives, the urine culture contamination rate remained at 40%.  Ed partnered with Mary E. Lough, then a CNS in the ICU and now a Research Scientist in the Office of Research Patient Care Services (ORPCS), to study how urine contamination might be lowered. They developed a research protocol and secured funding to hire new graduate RNs as research associates for patient enrollment and data collection. Later, the team expanded to include Debbie Hsieh for data management and Haley Hedlin for statistical analysis.

Data collection took over 10 months between December 2015 and September 2016. Data analysis occurred in 2017 and 2018, and the study was published in September 2019.

As with many research studies, this one took longer than expected to complete!


INTRODUCTION: A midstream clean catch urine sample is recommended to obtain a urine culture in symptomatic adults with suspected urinary tract infection (UTI). The aim of this randomized controlled trial was to determine whether a novel funnel urine collection system combined with a silver-colloidal cleaning wipe would decrease mixed flora contamination in midstream clean-catch urine cultures from ambulatory adults in the Emergency Department.

METHODS: In a 2×2 factorial trial, adult participants were randomized to four groups. (A) sterile screw-top urine collection container paired with a castile-soap wipe (control group); (B) sterile screw-top urine collection container paired with a colloidal silver-impregnated wipe; (C) sterile urine collection funnel paired with a castile-soap wipe; (D) sterile urine collection funnel paired with a colloidal sliver-impregnated wipe.

RESULTS: The trial was stopped after interim analysis, as the contamination rate in the control group (30%) was markedly lower than the historical ED contamination rate. From 1,112 urinalysis results, 223 urine culture results were analyzed (190 females and 33 males). Urine contamination rates were: Group A (control), n=67 (29.9 % contaminated); Group B, n=69 (34.8 % contaminated); Group C, n=51 (23.5 % contaminated); Group D, n=36 (22.2 % contaminated). Although some groups have lower percentage values, there was no statistical difference in contamination rates between any of the groups (p=0.369).

DISCUSSION: The use of a funnel urine collection system and silver-impregnated wipe did not reduce urine culture contamination in adult midstream clean-catch urine cultures in the Emergency Department.

If you’d like to read the published article in full, you may download a PDF copy by clicking here.


Lough, M.E., Shradar, E., Hsieh, C., Hedlin H. Contamination in Adult Midstream Clean-Catch Urine Cultures in the Emergency Department: A Randomized Controlled Trial. Journal of Emergency Nursing, 45(5), 488-501.


Article By: Mary E. Lough

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