The phrase "preservation method" refers to a way or technique used to keep something in good condition and prevent it from spoiling or deteriorating. Full definition
Cream you can always turn into butter — that's the oldest preservation method in the book. (bonappetit.com)
The way is so basic that it is sometimes overlooked among preservation methods. (fieryfoodscentral.com)
Your best bet is to see a fertility specialist and consider sperm banking or other fertility preservation methods before utilizing testosterone. (tctmed.com)