OBJECTIVE: To estimate and compare contamination rates of three different urine-sampling methods in pregnant women to assess bacteriuria.
METHODS: In this cross-sectional study, 113 pregnant women collected three different midstream urine samples consecutively: morning (first void); midstream (void without further instructions); and clean-catch sample (void after cleaning). The following end points were considered contaminants: epithelial cells, Gram-positive rods or mixed bacteria in the Gram stain, and mixed growth or skin flora in the urine culture. Intraindividual variability in contaminants was quantified with Fleiss-Cohen's weighted κ statistic. Differences between samples were assessed using generalized estimating equations.
RESULTS: Mainly low numbers of Gram-positive rods were more likely to be present in Gram stains of midstream samples compared with clean-catch samples (77.7% compared with 66.7%, P=.022). Morning samples showed more mixed growth compared with midstream samples (6.2% compared with 0.9%, P=.050). No consistency in quantity of contaminants was found in midstream samples compared with morning and clean-catch samples. No differences were found between the other end points in all three urine samples (P>.05). The study could detect an odds ratios of 2.0 for differences in urine-sampling methods with 80% power and 5% significance for most end points.
CONCLUSION: In pregnant women, the contamination rate of midstream samples is comparable with the contamination rates of morning and clean-catch samples. The quantity of contaminants varied among the three samples collected by one woman. These results show that more complex, unpractical, and time-consuming morning and clean-catch samples are not superior. Therefore, we recommend a midstream sample to assess bacteriuria in pregnant women.
Written by:
Schneeberger C, van den Heuvel ER, Erwich JJ, Stolk RP, Visser CE, Geerlings SE. Are you the author?
Departments of Internal Medicine, Division Infectious Disease, Academic Medical Center, Amsterdam, The Netherlands.
Reference: Obstet Gynecol. 2013 Feb;121(2 Pt 1):299-305.
doi: 10.1097/AOG.0b013e31827e8cfe
PubMed Abstract
PMID: 23344279
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