On vaginal examination, which level +1 station of the foetal head determines the foetal presenting part?

Correct option is B

In obstetrics, fetal station refers to the position of the fetal presenting part in relation to the ischial spines of the maternal pelvis. +1 station means the presenting part is 1 cm below the ischial spines, indicating the fetus is descending through the birth canal. This assessment helps determine the progress of labor and the readiness for delivery.
Explanation of options: (a) 1 cm above the iliac crest – This is anatomically unrelated to fetal station, which is measured in relation to the ischial spines, not the iliac crest. (b) 1 cm below the ischial spines – This is the correct answer. It defines +1 station, indicating that the fetal head is moving downward, progressing into the pelvic cavity. (c) 1 inch above the symphysis pubis – This is not a standard anatomical reference used in determining fetal station during labor. (d) 1 inch below the coccyx – The coccyx is posterior and not used for measuring fetal station; this location is not part of standard obstetric examination.