Computer-aided sperm analysis: past, present and future.

Computer-aided sperm analysis (CASA) system has been accepted and used commonly as a routine semen analysis instrument in hospital clinical laboratories worldwide. However, technicians in clinical laboratories have little informed knowledge about the principles of CASA system and the sources of analysis errors. In this review, we focus on the concept of CASA, the development course of CASA technology, the clinical application of CASA systems and the factors influencing the accuracies of results, such as frame rate, sperm counting chambers affiliated to the CASA system, algorithms and sperm concentration. These factors and lack of internal quality control may result in huge errors of the CASA between systems and laboratories. It is therefore necessary to perform the standardisation and quality control for CASA.