AIM OF STUDY
The diagnosis of voiding difficulties in women is not very well defined. In fact, compared to men, different anatomical and physiological aspects must be considered (prolapse, shorter urethra etc). In clinical practice the symptoms rarely combine with urodynamic parameters and it is still disputable which are the ones more indicative for voiding problems. The pressure/flow study nomograms applied for men are not reproducible in women and only in few cases it is possible to define an obstructed patients on the basis of urodynamics. The aim of this study was to evaluate in a group of frankly obstructed women if any urodynamic parameter, apart from the peak flow rate and the maximal detrusor voiding pressure, could be indicative of bladder emptying difficulties in order to use them in less evident situations to help diagnosis.

METHODS
We retrospectively analysed a database of women with urinary tract dysfunction and an urodynamic diagnosis of obstructed voiding. Obstruction was defined when the peak-flow rate was < 15ml/sec and the maximal detrusor voiding pressure > 60cmH2O. From this group of patients we tried to identify any other urodynamic finding, using different cut-off values, which could be indicative of their condition such as post-void residual, the ratio between the post-void residual and the voided volume and the maximal urethral closure pressure (MUCP). The MUCP was adjusted to age according to Rud formula: [(110 - age) x 110/100]. The data were analysed in terms of cumulative percentage at different cut-off values.

RESULTS
The urodynamic parameters of five-thousand-two-hundred-and-eight women with a mean age 52.2 years (range 27.0 - 79.0yrs) complaining of urinary tract dysfunction were analysed for this study. Eighty-one women (1.5%) with a mean age of 48.6 years (range 29.1-71.9 years) had a final diagnosis of obstructed void. When the post-void residual was analysed we could not get data from 3 women (3.7%). Table 1 shows the cumulative percentage of this group of obstructed women when different cut-off values for post-void residual were used. Table 1. Cumulative percentage when different cut-off values of post-void residual were used.

Using different cut-off values for the ratio between the post-void residual and the voided volume expressed in percentage, we had the findings shown in table 2. Table 2. Post-void residual/voided volume % with different cut-off values

The MUCP adjusted to age according to the Rud formula was normal in 61.8% of the women considered.

CONCLUSION
In this group of obstructed women 41.1% could not void during urodynamics. A post void residual > 150ml and a ratio between the post-void residual and the voided volume expressed in percentage of 50% could be considered indicative of the final urodynamic diagnosis and therefore used as ancillary parameters in less evident situations of voiding difficulties. On the contrary the MUCP adjusted to age does not seem to be of any value in discriminating voiding difficulties in women.