Detrusor pressures in urodynamic studies during voiding in women

Introduction and hypothesis To investigate detrusor pressure during voiding in women using urodynamic studies (UDS). Methods The study group comprised 57 women with non-neurogenic lower urinary tract symptoms. All patients underwent UDS between January 2010 and December 2014. UDS included filling cystometry, pressure flow study (PFS), uroflowmetry for the maximum flow rate ( Q max) and mean flow rate, and postvoid residuals. Existence of voluntary detrusor contraction was defined as a continuous and smooth increase in detrusor pressure ( P det) after the instruction to micturate in the PFS. The bladder contractility index (BCI) was calculated as P det at Q max + 5 × Q max. Statistical analyses were performed using the Mann–Whitney U test and p < 0.05 was considered statistically significant. Results The PFS showed that 23 patients had detrusor contraction ( P det+ group) and 34 patients had no detrusor contraction ( P det− group) during voiding. There were no significant differences in urodynamic parameters between the P det+ and P det− groups except in P det at Q max and BCI. In the P det− group, 21 patients showed an increase in abdominal pressure during voiding ( P abd+ group), while the other 13 patients did not ( P abd− group). There were no differences in any of the urodynamic parameters between the P abd+ and P abd− groups. Conclusions Based on UDS, an increase in detrusor or abdominal pressure may not be necessary in micturition in women. The present study suggests that relaxation of pelvic floor muscles including normal urethral function are important for micturition in women.