We almost ran into this problem a many years ago. We had not been swinging for a while and my wife was not on the pill. I have had a vasectomy. We were at friends home and things got a little erotic. One thing led to another and we ended up swapping. Then of course my wife was late. So this was a possibility we had to discuss. We quickly decided that we would keep this to ourselves and handle it together. Abortion became the first possibility. It would be dificult telling people that my vasectomy had somehow reversed itself but that was an option also. Fortunately nature finally took it's course and we were relieved. Of course since then we are much more careful.