The short answer is: they don't. Well, not always...
Our CLIA-certified lab is not looking at the quality of the cells in a Vasectomy sample, but rather if there are any sperm cells present at all. A key factor here is our preservation solution which is catered to preserving the cell integrity of any sperm that is present. This means that the cell won't disappear (and our lab team will still find it!) even if it dies during transit.