It has the possibility of about 0.00000000000001 %

Semen can only survive in a friendly environment (the insides of the vagina or of course, inside the testicles). After the guy came (on the floor), it is "usable" for its real purpose only for like a minute. So, he'd have had to cum, lick it from the floor and suck this woman's pussy all in a minute. And even then, the possibility of the semen itself going inside the uterus by its own means is remote. And then, it has to encounter an egg, which millions of spermatozoids find difficult, a much less quantity is even less likely to do so.

My 2 cents