Objective: To apply Superimposed Image Analysis System (SIAS) software (Delta Sistemi, Rome, Italy) to the objective analysis of sperm motility. Design: To test a new procedure for sperm motility assessment based on image superimposition. Results: The system can superimpose six sequential frames onto a monitor producing a final image with a motion effect similar to the multiple exposure photography method, but bypassing the film processing stage. Viewing the final image of a complete series of six superimposed frames allows the evaluation of the percentage of motile spermatozoa and their kinetic characteristics. Compared with multiple exposure photography, SIAS has the following main advantages: [1] the procedure is quick; [2] projecting the first frame alone allows the easy evaluation of sperm concentration; and [3] the system allows quick and easy analysis and measurement of each sperm trajectory frame by frame, thus avoiding misleading interpretations because of crossing sperm trajectories, collisions, and overlapping of motile spermatozoa with round cells or immotile spermatozoa. Conclusions: Superimposed image analysis is a new approach to sperm motility assessment. It seems to be useful particularly in selected situations, such as oligozoospermia or in cases of increased round cell concentration. In these situations, SIAS can even serve as a support or an alternative to the computer-aided sperm analysis system widely used for objective sperm analysis.
