How long for retained products of conception to pass naturally?

[TheMagpieRobin]

I had a D&C six weeks ago and had bleeding that never settled and a scan showed retained products. I think I've had one period post procedure and a small amount of tissue like stuff came out with that but another scan confirmed there was still an 18mm piece remaining.

I've got a follow up appointment in three weeks (so nine weeks post procedure) and have been told that at that point they'd recommend repeating the D&C if any tissue is still there and I'm still bleeding.

Has anyone else had this and how long did you wait and did the tissue come out on its own?

I had a blighted ovum that miscarriaged naturally at 13 weeks, but I had retained products. For various reasons I didn’t want any intervention. Eventually I got silica tablets from an alternative medicine lady; I put 1 under my tongue when I went to bed and by the morning it was out, no pain. This was 2 months later.