Status Plus





King's Coll. Hosp., London, United Kingdom.

Introduction: Laboratory urodynamic studies fail to diagnose up to 30% of patients with lower urinary tract symptoms (1). Ambulatory urodynamic monitoring improve diagnosis, but is costly, time consuming and requires specialist input (2). Pressure flow studies in men are useful in those with bladder outlet obstruction secondary to prostate hypertrophy, where increased bladder contraction strength is associated with detrusor overactivity (DO) (3). Their use in women is less well understood. Work by Digesu et al (2) showed that detrusor pressures are lower in those with urodynamic stress incontinence (USI) and higher in those with DO. A theory for this includes hypertrophy of the urethral sphincter in those with DO, secondary to contraction of the muscle to prevent incontinence (2). Therefore the bladder has to generate a greater pressure to empty in those with DO.
Objective: To compare our urodynamic data of different pressure flow parameters in women with lower urinary tract symptoms.
Methods: This was a retrospective study of consecutive women who attended our tertiary level urodynamics clinic. All women underwent assessment including history, physical examination, urine analysis, uroflowmetry, videocystourethrography, pressure flow studies and post void residual (PVR) measurement. Urodynamics were performed by trained doctors and specialist nurses in keeping with Good Urodynamic Practice. Four groups were identified; those with USI, DO, mixed urodynamic incontinence (MUI) and normal urodynamics. We excluded those with voids less than 150mls or residuals greater than 100mls or an ordinal pelvic organ prolapse score greater than 1. We focused on the isovolumetric contraction pressure (Piso), opening detrusor pressure (PdetOpen), detrusor contraction at maximum flow rate (PdetQmax) and maximum flow rate (Qmax). Data were collected using an Excel spreadsheet and statistical analysis using SPSS version 23. We used Bonferroni corrections to test significant differences between the pressure values.
Results: We had a total of 328 patients with Piso data and 541 patients with data for the other pressure parameters. In the Piso arm, there was no significant difference between those with normal urodynamics and MUI, otherwise there was a significant difference amongst the other groups. In the PdetOpen and PdetQmax arms, there was no significant difference between normal urodynamics vs MUI and USI vs MUI, otherwise there was a significant difference amongst the other groups. In the Qmax arm, there was only a significant difference between normal urodynamics vs USI and DO vs USI, otherwise there was no significant difference amongst the other groups. The DO group had significantly greater pressures than the USI group for all four pressure parameters. Table 1 summarises the results.
Conclusions: Our study confirms findings by Digesu et al (2) by demonstrating that women with DO had significantly higher pressures than those with USI. This may be because those with DO have a hypertrophied sphincter compared to the weakened sphincter in USI. Our results differed as our patients with MUI did not have a significant pressure difference from those with USI in all parameters except Piso. There was no significant difference between those with MUI and normal urodynamics in all pressure parameters. It appears that those with MUI have pressures which are halfway between USI and DO i.e. they even themselves out. Pressure flow studies may be a useful tool to help identify patients complaining of stress incontinence and overactive bladder, but further work is needed on those with MUI.
References: 1.British Journal of Obstetrics and Gynaecology (1980); 87: 893-896
2.Neurourology and Urodynamics (2004); 23:104-108
3.Neurourology and Urodynamics (2005); 24:202-206