Which voiding position is associated with lowest flow rates in healthy adult men? role of natural voiding position.

PURPOSE

To investigate the effect of voiding position on uroflowmetric variables and postvoid residual urine (PVR) volume in healthy adult men without lower urinary tract symptoms (LUTS).

MATERIALS AND METHODS

Men without LUTS were enrolled. Participants were asked to report to the urodynamic suite with comfortably full bladder for uroflowmetry. Each participant performed six voids into digital uroflowmeter (Solar Silver, Medical Measurement System, The Netherlands), all on separate occasions, twice in each of the standing, sitting, and squatting down positions. PVR was measured using transabdominal ultrasound (Siemens).

RESULTS

Total 72 participants were enrolled and 61 completed the study; their mean (+/-SD) age was 26.6 +/- 6.9 years. All of them but one was accustomed to void in standing and squatting positions. The mean maximal flow rates (Q(max)) and average flow rates (Q(ave)) were significantly lower in sitting position, than standing and squatting positions (Q(max): 19.8 +/- 7.4 vs. 23.8 +/- 7.7 and 24.4 +/- 8.1 ml/sec, respectively; P = 0.0001. Q(ave): 11.2 +/- 4.5 vs. 13.9 +/- 4.5, and 13.8 +/- 5.1 ml/sec, respectively; P = 0.0001). The corresponding values of voiding time were significantly higher (t(vv): 38.6 +/- 20.7 sec vs. 28.3 +/- 15.3 and 30.6 +/- 18.1 sec, respectively; P = 0.0001). The latter two positions were statistically similar in voiding characteristics. Voided volumes and PVR were statistically similar among all the three positions.

CONCLUSION

Uroflow parameters were higher in standing and squatting positions compared to sitting in individuals not accustomed to void in sitting position. Therefore, uroflowmetry should not be performed in a position the individual is not familiar with.