A Man Fingered Into A 18 Yr Old Girls Vagina

A man fingered into a 18 yr old girls vagina after 7 days of the period is over. Not sure whether the finger was dry or had pre cum or semen. Wether pregnancy can occur or not? Test to check d same. Time when to carry on check? Ehether i pill csn be taken before test n will there b side effects? If the result turns out to bd positive can it be prevented completely?