The effect of specimen processing delay on borate urine preservation.

Aim: To investigate the effect on urine culture results and their clinical interpretation of delaying the processing of urine samples in which boric acid had been used as a preservative.
Methods: 792 mid-stream specimens of urine from patients attending their general practitioner were received in borate containing plastic jars. The specimens were cultured upon receipt, stored at room temperature, and then recultured the following morning.
Results: After overnight delayed culture, the results were altered in 16% of samples and the clinical interpretation of these findings differed in 8% of specimens. In 28 samples (3.5%) the bacterium isolated on initial culture was not the same as that obtained by culture after overnight storage.
Conclusions: Boric acid urine preservation used for overnight delayed processing of samples is associated with a significant alteration in culture results and the attendant clinical interpretation of such specimens. Rapid transportation/processing of urine specimens must remain the optimum procedure.