Sometimes a baby at term hatches with yolk sac attached. Depending on your incubation temp, 47-48 days may be term. I had a baby hatch at 49 days a few weeks ago that was very tiny (1 gram) with a huge yolk sac attached and a lot more yolk in the egg. Its clutchmate hatched 2 days later without a yolk sac at full size. I have a rack for the babies and I put this one in the rack in a small container. By day 2 it had climbed out of the container and was roaming around the tub, but it only lived 3 days. I think it was just too small and obviously had not absorbed nutrients properly to be so small at that point in egg development. I have had a few others hatch with yolk sac attached or something that looks like an umbilical cord and they all (except for this tiny one) have done well. You could keep it in the incubator, but you can also put it in an enclosure, keep it warm and moist and give it time to either drop or absorb the yolk. If it doesn't survive, it may not have been strong enough to live.
Aliza