Is it possible to predict post-residual voided urine by bladder scan before uroflowmetry--a useful and timesaving test to reduce the number of non--evaluable uroflow measurements?

OBJECTIVES

Bladder-scan before uroflowmetry is useful to reduce non-evaluable Q(max)-data. A significant problem is to receive an adequate voided volume in uroflow-measurements. Aims of this study were 1--to confirm if pre-voiding bladder scan can reduce the number of inadequate flow measurements, 2--to establish threshold values for prevoiding bladderscan volumes before and after different treatments options 3--to study if it is possible to predict the post-residual voided volume.

MATERIAL AND

METHODS

121 patients performed 2 uroflowmetry before and after different treatments. Bladder volume was measured by transabdominal ultrasound when the patient had the sensation to void and after uroflowmetry to calculate residual urine. Same investigations were repeated after different treatments.

RESULTS

21% of the patients had insufficient voided volume < 125 ml in 1st recording and 22% in 2nd; while 28% of the patient had a volume voided < 150 ml in 1st recording and 33% in 2nd. There was a strong correlation between the pre-voiding measured volume and the voided volume (r = 0.801, p < 0.0001), linear regression analysis yielded 1st flow rate recording is Void-Vol = 32.703 + (0.637 * Pre-Vol) and 2nd flow rate recording is Void-Vol = 16.264 + (0.704 * Pre-Vol) (r = 0.855; p < 0.0001).

CONCLUSIONS

Bladder scanning before uroflowmetry reduces the number of non-evaluable Q(max) data. If a voided volumes of > 125 ml (> 150 ml) is required a mandatory pre-voiding bladder scan volume should be > 200 ml (> 250 ml), so non elegible Q(max) recordings will decrease from 21% to 5.8% (28% to 4.1%) in BPH patients who will undergo treatment and from 22% to 7.4% (33% to 5.8%) in BPH-treated patients. There is a difference between patients before and after treatment. It is not possible to predict the post residual voided volume by the bladder scan using the virtual calculation.