Had a mom call after she expelled what looked like a sac: red and very fibrous with fat- like tissue attached. Her baby is six months old and she was concerned that she may have miscarried. There was a lot of cramping and blood with the passage of the sac. Her OB told her it was a decidual (sp) cast, not and a blited embryo. He also said that such casts are common after menses have been delayed (or skipped) and after childbirth. I have never heard of this. Could one of our MD's respond as to what it is and how it forms? Marie Davis [log in to unmask]