Evaluation of urine sampling technique: bacterial contamination of samples from women students.

A urine specimen is traditionally sampled using the clean-catch midstream technique, but this technique is poorly documented. The aim of this study was to evaluate the bacterial content of urine samples taken using individual steps of the clean-catch midstream technique, or combinations of steps. One hundred and ten women students provided a total of 864 early morning urine samples, using a different sampling technique each morning. Holding the labia apart during sampling more than halved the percentage of samples containing 10(5) colony-forming units per ml or more, and increased the percentage of uncontaminated samples, compared with passing urine without employing any of the precautions. Cleaning the perineum or using the midstream technique resulted in percentages no different from urination without employing any precautions. It is therefore recommended that women should be instructed to carry out the simplest effective urine sampling technique: holding the labia apart.