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Red-topped boric acid containers

The preservative in red-topped boric acid containers reduces the overgrowth of organisms and, to a lesser extent, reduces the degradation of white cells during transit. This leads to a more accurate laboratory result for both microscopy and culture.

UKAS recommends the use of boric acid containers for all urine sample for microscopy and culture (Urine M,C&S) to improve the quality of microbiological results.

Red topped boric acid containers are for requests for urine microscopy and culture (MC&S) ONLY. Boric acid container should NOT be used for:

  • Other urine microbiology tests (e.g. investigations for Chlamydia, Mycobacterium, Schistosomiasis, urinary antigen testing)
  • Urine samples being analysed by PCR methodology
  • Urine samples for non-microbiology tests (e.g. biochemistry, virology, pregnancy testing)
  • Very small urine volumes (<20ml) e.g. neonates

Use of urinary dipsticks: boric acid may inhibit leukocyte esterase dipstick readings; dipstick testing performed on a sample in a boric acid container should be interpreted with caution.

If additional tests are required in addition to urine microscopy and culture, an additional sample in a white-topped universal container should be sent. In this case, it is advised that the mid-stream clean catch urine is collected in a sterile bowl and then transferred to the necessary specimen containers.