What is the relationship between free flow and pressure flow studies in women?

Introduction And Hypothesis: The relationship between free flow (FFS) and pressure flow (PFS) voiding studies remains uncertain and the effect of a urethral catheter on flow rates has not been determined. The relationship between residuals obtained at FF and PFS has yet to be established.

Methods: This was a prospective cohort study based on 474 consecutive women undergoing cystometry using different sized urethral catheters at different centres.