Are you saying you had sex, and then three days later had your IUD removed? Sperm can live up to 5 days in the (female) reproductive tract, so there is a chance. You would have to have ovulated sometime in that three days and then the sperm would have needed to find the egg, and then the IUD would need to be out of there so the embryo would implant. It is not the likeliest way to get pregnant, but it would not be impossible.
You can become pregnant anytime you have sex.