A 32-year-old G3P2 at 39 weeks gestation is in the second stage of labour. After 90 minutes of active pushing, the fetal head is at +3 station in the right occipitoposterior (ROP) position. Fetal heart rate shows a baseline of 130 bpm with absent variability and recurrent late decelerations. The cervix is fully dilated and the perineum is bulging. The obstetrician plans instrumental delivery. Which of the following is the MOST appropriate next step?