Skiptonlass
"Can I ask a question? How feasible is it to say in your birth plan that you do not consent to forceps and would prefer to go to cs rather than have them?"
There is no arm writing this in your birth plan. As other posters' experiences show, it doesn't mean your plan will be followed but you can try.
It might be that you'll need to start arguing well before they mention the word "forceps" (probably as soon as your labour is not progressing anymore).
"Is there a point where the baby is too far descended to do the cs and thus forceps/ventouse are inevitable?"
In my case, the short answer is "I don't know". Neither my baby nor I were in distress.
I had an epidural (I lacked the support I would have needed-hubby did what he could but sadly was not up to the job (no hard feelings against him as he was just out of his depth) and triage midwife was not kind (more hard feelings there as she was trained and supposed to be there for me)). All well until fully dilated. Then baby was stuck. At that point (because of my lack of awareness about instrumental deliveries), I was not worried about what next. I naively thought they might use a ventouse and that would be it.
I was left one hour to see if baby would come out (I checked afterwards and that is the recommended procedure for someone with an epidural, they also turned me on my left side). Nothing. Obs was called in. Her words: "Your baby is almost there and in an optimal position, we'll use a ventouse and get him out." Ventouse failed.
Second obs comes in. Tries the ventouse again. Fails. At that point, 2 things were said:"I'm sorry, we sometimes don't know why ventouse fails" and "we're now going to move to forceps". Then "people invade the room" (2 obs, 2 midwives, 1 paediatrician, 1 somebody to hold the lights and probably more I can't remember). Then they explain they have to perform an episiotomy so they can use forceps and then they ask me to work with them and with the contractions to push. One series of 3 pushes and baby is out. And I start bleeding, a lot. Too much for delivery room so wheeled off to theatre to deliver placenta manually, stitch me back together and transfuse me.
I debated whether to write all my birth down (it is I'm sure unremarkable for a forceps delivery) and decided that it might be useful. As you can see, there was no discussion about risks. I was unaware of the risks of forceps (and use of instruments in succession or effect of prolonged second stage on pelvic floor for that matter) and because my baby's heart rate was fine, I was not worried.
All I'm trying to say is if there is no clear cut emergency, you might want to try discussing procedures before they actually happen. Easier said than done. A well briefed birth partner might be useful.
3 basic questions might have helped us:
What is happening?
What does that mean?
What options are there?
If other posters were successful in articulating their choices when things were not going well, I personnally would be interested to learn how things unfolded (what was said and when).