This means that when sperm enter your vagina, they are caught in the mucus lining the cervix and cannot swim through to find the egg. The plastic iud (and I think the ring) work by increasing the mucus level created in your vagina covering the cervix opening. They will run out and be absorbed into the lining and then removed through period as regular. In this case the sperm will not be able to swim around or look for the egg as they have been killed instantly. The copper iud and implant work by increasing the acidity of your vagina, and adding another element that will cause the sperm to decapitate upon entering the vagina. They just would run out sooner rather than be absorbed. So the sperm will do the same things as they normally would. The pill works by eroding the lining around your vagina, making it near impossible for a fertilized egg to attach. Eventually it will run out from either being ejected when peeing, or from the lining shedding during your period. Some will be absorbed by the lining and mucus on the vagina wall. Some will swim around looking for your egg to fertalize for up to 7 or so days. Some of the sperm will die right away from the acidity of the vagina. A lot of it will flow back out afterward.