If she was going for an instrumental, that would have been because there was a delay in second stage. One of the things we do to try and resolve this is empty the bladder as that can help the head move down. For this we would use an in out catheter. This is just a small tube that we place into your urethra and when the bladder is emptied we take it out. This obviously did not help, and it wasn't clear whether an instrumental birth was possible. When in this situation we go for a trial on theatre so the instrumental can be attempted then if this does not work the woman can have a section.
Once transferred to theatre the woman is prepped for spinal, once the spinal is in place they are assisted to lie down and the reg will reassess with a vaginal examination to see if the head is low enough or in a good enough position to attempt the instrumental. In this case it sounds as though it was and a forceps was used.
If this had not been the case and a section was indicated, the midwife would then insert the indwelling catheter (this is the one with the bag on the end, and is kept in place with a small balloon). This would stay in place until the woman was mobile and able to get to the toilet.