What are the chances for Pre-cum to contain sperms?

Patient: Hey, Ive recently had sex with my girlfriend today. We had safe sex I used a condom and pulled out well before I ejaculated. The problem we had was when I first put the condom on it was “backwards” therefore it did not go down. I took it off and switched the sides to put it on properly being extremely cautious of any precum. I whipped the top of the condom where any precum could have gotten on. I understand from other health forums that if I ejaculated hours of days before and took a pee the precum does not contain any semen. Please give me some background information and if I should be worried about her getting pregnant. I know I am probably over-reacting and being paranoid but this was my first time so I am curious thanks.

Doctor: The pre cum may contain few sperms, but chances of getting pregnant with pre ejaculate is very rare. Pre cum is similar in composition to semen with some chemical differences. Usually, if you have ejaculated a few hours before, there are chances for the left over sperms from the previous ejaculate to be present in the precum. However if you pee before having sex you may flush out some hidden sperms from the previous act. Peeing may reduce the number of sperms in the precum, but in my opinion there would always be a risk of presence of few sperms despite ejaculation hours or days before having sex.