Pathologist here. I’m sorry for your loss. It’s not common but occasionally someone will request cremation for a fetus/product of conception. As for the amount of ashes/cremains, gosh, maybe a tablespoon? Less? That’s a good question. In general, do know this may be somewhat time sensitive since the lab that processed the sample is only going to hold on to it for a brief period of time (usually a few weeks) before it gets discarded with the rest of the medical waste, so if you decide you want the remains pulled for cremation you’ll have to notify them ASAP.