Fig. 2.

Illustration of how to calculate vertical movement of the cervix using the Pelvic Inclination Correction System (PICS), accounting for pelvic rotation that occurs during Valsalva. P inferior point of the pubic bone; C midpoint of external cervical os; SCIPP sacrococcygeal-inferior pubic point; d^rest vertical distance of the cervix from the PICS line at rest (negative values above the PICS line, positive values below the PICS line); d^Valsalva vertical distance of the cervix from the PICS line during maximal Valsalva. Total vertical movement of the cervix = ∣d^Valsalva – d^rest∣