My mum had 2 forceps deliveries on her back with both my brothers 11lb and 10lb, posterior, foetal distress and stuck so she had to have a full episiotomy through to her anus and Dad thought bubs head was gonna pop off the Doc was pulling so hard to get him out urgently with his foot on the end of the bed etc- she said for the first few weeks no control over bowel motions/urgency - so same problem. But she never had any ongoing problems with that recovered fine after the first few weeks, had the same thing after my next brother, but again wasn't ongoing didn't need physio though to get continence back - that might make a difference. My birth was natural as I was healthy and not stuck- she DID tear with me but not all the way through so didn't have the problem with foecal incontinence at all. Hope that helps.

I understand the fear of tearing though - I only tore 2nd degree (didn't push when crowning and was on my knees but just bad luck) tore in 3 directions, they had to call the OB to come stitch as was very awkward, but the stitching up memory is the biggest scare factor for me going back again as I can't believe how excruciating that 40min was (plus the 5 months it took for no pain upon 'activity'). So don't mind if I have to CS next time for any other reason.

Also, my gf tore 3rd degree (took them 3 hours in OR to stitch her up blood loss etc) OB recommended Caesar for her next one too - but if she did want to VB to be in a position the midwife could see when bub crowning in case was due to over-pushing as she was waterbirthing and midwife didn't have clear view. So they do admit that there can be reasons - forceps deliveries are terrible so you might be fine next time. All the best with your decision.