Validating semen processing for an intrauterine program should take into consideration the inputs, actions and the outputs of the process.

To validate semen preparation via density gradient centrifugation, we took into account the input via the semen sample, the action generated by technical and equipment characteristics and the output measured by the level of performance. Longer periods of abstinence reduced % yield, but increased viscosity and incomplete samples collected had no effect. Under controlled technical and equipment characteristics, precision and reproducibility were validated for density gradient. Additionally, as a good laboratory practice, internal and external quality control measures were implemented to guarantee the level of performance. Inseminating motile sperm count is an important predictive parameter for IUI success. In our group of patients, a yield of an absolute lower limit of 2 million motile spermatozoa was sufficient to contemplate IUI. Pregnancy rate of 13.8% where >2 million rapid progressive spermatozoa were inseminated was significantly higher than the pregnancies (4.4%) obtained with <2 million rapid progressive spermatozoa. This percentage was even higher than the national data registered for IUI (12.2%). To make IUI an attractive first-line treatment, standardization and proper validation of semen preparation procedure are mandatory.