Interpretation of semen analysis using WHO 1999 and WHO 2010 reference values: Abnormal becoming normal.

Reference values of WHO 1999 manual were used for the interpretation of semen analysis until 2010 when new reference values were introduced which have lower cut-off compared to WHO 1999. Therefore, several men who previously were diagnosed abnormal based on their semen analysis have now become normal using new reference values. This study was conducted on semen analyses of 661 men from Middle East region and Pakistan. All semen analyses were reviewed using WHO 1999 and WHO 2010 criteria. Results showed that based on new criteria, 19% of the population changed classification from abnormal to normal when all normal semen parameters were considered. When at least one or more abnormal semen parameters were considered, of the total 661, 44% (288) of the population changed its classification from abnormal to normal with shift from WHO 1999 to 2010 criteria. These findings show that using new cut-off values, many more men are considered normal, but using old criteria (WHO 1999), the same men would be classified as abnormal. This warrants further discussion over the investigations and management plans for patients whose semen analyses fall below WHO 1999 but above WHO 2010 cut-offs.