What it means
Most often it is the back of the head (vertex). In a breech presentation it is the buttocks or feet, and in a transverse lie it may be the shoulder. How far the presenting part has moved down into the pelvis is called its station, measured in centimeters above or below the ischial spines.
For the nurse
If the membranes rupture before the presenting part has moved down into the pelvis, the umbilical cord can slip past it, so check the fetal heart rate right away after rupture.
Related terms
Leopold maneuvers
Four steps of feeling the pregnant abdomen with the hands to find how the fetus is lying in the uterus.
umbilical cord prolapse
A condition in which the umbilical cord slips through the cervix ahead of or beside the fetus's presenting part.