WHO 6th edition recommends reporting these categories of movement:
- Rapidly progressive (25 µm/s): spermatozoa moving actively, either linearly or in a large circle, covering a distance, from the starting point to the end point, of at least 25 µm (or ½ tail length) in one second
- Slowly progressive (5 to <25 µm/s): spermatozoa moving actively, either linearly or in a large circle, covering a distance, from the starting point to the end point, of 5 to <25 µm (or at least one head length to less than ½ tail length) in one second
- Non-progressive (<5 µm/s): all other patterns of active tail movements with an absence of progression (i.e., swimming in small circles, the flagellar force displacing the head less than 5 µm (one head length), from the starting point to the endpoint)
- Immotile: no active tail movements
Complete the assessment of progressive motility in the area of observation, followed by non-progressive motility, and finally immotility.
The lower reference limit for progressive motility is 30%. The lower reference limit for total motility (progressive + non-progressive) is 42%.
The attached video provides several examples of progressive motility. This video and the video on the following page are used with the permission of Kokopelli Technologies, LLC.
