FAQ1: How is the concentration of round cells calculated?
Count the number of round cells whilst determining the sperm concentration in a routine semen analysis. If the concentration of round cells exceeds 1×10⁶ cells/ml, additional testing with LeucoScreen Plus is recommended.

FAQ2: What are the advantages of the LeucoScreen Plus kit compared to the LeucoScreen kit?
The LeucoScreen Plus kit is equally suitable to distinguish between peroxidase-positive and peroxidase-negative round cells, but has the major advantage of not containing a carcinogenic substrate when compared with the LeucoScreen kit.

FAQ3: For how many tests can the kit be used?
There is enough reagent to create the work solution 20 times. The work solution is stable for 2 days, so the kit contains reagents for 40 days of testing.

FAQ4: How to evaluate peroxidase-positive versus -negative round cells?
A demonstration video is available on the LeucoScreen Plus product page. A training is available upon request.

FAQ5: Can we perform the LeucoScreen Plus test in case of very high or low round cell concentrations in the sample?
In some semen samples, you might prefer to enrich the round cell concentration to facilitate cell counting. Therefore, centrifuge the sample for 15 minutes at 350g, remove some volume of the semen sample and resuspend the pellet.

FAQ6: Can a Neubauer counting chamber (or other (WHO compliant) counting chamber) be used instead of a regular slide?
Other counting chambers can be used to count the results of the LeucoScreen Plus test. When using such counting chamber the provided calculations are no longer needed as you get a precise counting through the counting chamber.

In case of very high concentration of round cells (i.e. above 20×10⁶ per ml), it is strongly advised to dilute the sample in PBS or in FertiCult^TM Flushing medium.

FAQ7: Is there a QC protocol available?
Yes, there are 2 possibilities.

1. Compare results of an in-use kit with the new kit. % CV should be below 15%.
   % CV inter assay = stdev (old lot and new lot) / mean (old lot and new lot)
2. Add 2µl of a peroxidase solution (0.1mg/ml, for example Peroxidase from horseradish, P8125 – Sigma-Aldrich) to 200µl working solution. A black precipitate should be observed.