Is it possible for me to get impregnated by pre-cum if his penis wasn't near my "area". see, let me explain....

we have yet to do the actual "deed", but we've been keeping or sexual needs satisfied for the the most part by, well...more basic methods. the one in question is masturbation. while preforming the act on him, he decided that I need a little help, in all honesty this was new to me, I'd never given anyone a hand job. so he places his hand with mine and beings "helping".

what we're worried about is after "helping" he began to preform the above act on me.

Does anyone know of any pregnancies that have happened that way? if so, what are the chances of it happening?