Detrusor pressure uroflowmetry studies in women: effect of 4 Fr transurethral

Pressure flow technique on males is considered a standard diagnostic procedure to investigate the voiding process, while on female this is still under investigation. Many studies have been conducted in order to establish a female bladder outlet obstruction nomograms using a 7 Fr catheter, but recently a report showed that 7 Fr catheter may adversely affect the voiding process on women. We studied the effect of 4 Fr urethral catheter in women undergoing pressure flow evaluation in order to assess any detrimental effect in the voiding process.

We evaluated a database of 85 patients referred for lower urinary tract symptoms. First, all patients had free uroflowmetry and then underwent pressure flow studies utilizing two catheters: a 12 Fr for filling and a 4 Fr mono J for measuring detrusor pressure. After filling we removed the 12 Fr catheter and pressure flow was performed leaving the 4 Fr only in the urethra. As positive correlation of flow rate with voided volume is well established, we selected only 33 patients who had similar prevoided volumes varying by less than 30% and free and intubated flow parameters were compared according to volume categories in order to strengthen the statistic analysis.

In each group all the free and pressure flow parameters were not statistically different. Only in the group who voided within 250 and 500 ml we found the pressure flow voiding time to be almost longer than the free flow equivalent, but not statistically different (31.1 +/- 15 versus 56.7 +/- 49.3; p = 0.05). Furthermore we did not find any difference in free and intubated morphology of curves.

A 4 Fr transurethral catheter does not affect adversely the voiding process in women undergoing pressure flow studies for lower urinary tract symptoms. This finding has very important clinical implications for interpreting female voiding patterns and may be considered the best tool to define bladder outlet obstruction on women.