Since I attend quite a few epidural births, this is something I have to deal with a fair amount. For multips, it doesn't make a lot of difference as this can often push their babies out well regardless. Here's what I do for primips, though. First, some moms with an epidural still have a great spontaneous urge to push, and you can just go with it. Many of those moms with a good urge to push also have good movement in their legs and can still get in upright positions, too. For these women, we just proceed as normal, and I've had many an epidural mom squat or use hands and knees and have nice spontaneous births.
Some women, though, will not have any feeling at complete dilation. I have good luck with having these moms sit upright, or in supported hands and knees and just waiting. Often, after an hour or 2, the babe will descend enough that the woman feels pressure and can push spontaneously. If that doesn't work, I try to talk the mom into turning off the epidural. If she cant be convinced of that, only then will I sometimes try directed pushing. Often,getting mom sitting up or on her knees and encouraging her to push like she is trying to push out stool will get the baby moving. Of course, one of the problems with a woman who can't feel anything is that you also can't tell if she is moving the baby unless you start seeing external signs like the perineum bulging, or head showing-unless you do a lot of exams. I'm still not crazy about counting- I usually just ask moms to push until this feel they need a breath. Most of the time, eventually as the head descends the mom will feel a spontaneous urge to push at some point but sometimes that means we are working for a while without a good urge to help the mom. My main tip would be to "labor down" as long as possible and not start pashing until mom really feels an urge if at all possible. Usually, for me, with a mom who is way comfortable, this is a good time for a nap!