Performance of four chambers to measure sperm concentration: results from an external quality assurance programme.

What are the changes in the use of four types of counting chambers by laboratories enrolled in an Australian-based external quality assurance programme, and what are their accuracy and precision? Samples of latex beads of known concentration up to 20 × 106/ml were distributed quarterly to enrolled laboratories over a 12-year period. The results of each distribution were then used to calculate a bias relative to the target value as an indicator of accuracy and a coefficient of variation to indicate the level of precision. The proportion of laboratories in 2007-2008 using improved Neubauer haemocytometers (44%), Makler® (9%) and Vetriplast chambers (19%) remained constant in 2018-2019, unlike Kova chamber users (20%), which reduced. The mean (range) bias of improved Neubauer haemocytometers (-2.8% [-22.5 to +32.0%]) was less than Makler® chambers (+17.0% [-2.9 to +41.2%]), Kova chambers (+33.9% [0.0 to 115.0%]) and Vetriplast chambers (+47.9% [0.0 to 170.0%]). The coefficient of variation of improved Neubauer haemocytometers (14.6% [8.7 to 25.0%]) was less than both Vetriplast (20.7% [8.8 to 36.4%]) and Makler® (24.1% [13.6 to 48.6%]) and Kova chambers (35.5% [15.9 to 123.0%]). The improved Neubauer haemocytometer has been shown to be superior in accuracy and precision to the Makler®, Kova and Vetriplast chambers in their estimation of concentrations up to 20 × 106/ml. Users of Makler® chambers, specifically designed for counting spermatozoa, should take care to monitor the performance of their own chambers, whereas Kova and Vetriplast chambers (designed for microscopic urinalysis) should not be used.