Spontaneous versus intubated flow in male patients.

The spontaneous flow rate was compared with the flow rate obtained during a pressure-flow study with two 5F catheters in the urethra, in 57 male patients with various lower urinary tract disorders. Intubation caused a median decrease in maximum flow rate of 1 mL/sec (95% confidence limits 0-2 mL/sec). In patients with infravesical obstruction a significant decrease in maximum and mean flow rates was found whereas the flow rate was unchanged in the group of patients without obstruction. It seems that changes in flow rate due to intubation of the urethra is of minor importance compared with other factors and intubation may actually provide diagnostic information in diagnosing mechanical obstruction. It is concluded that the transurethral technique for pressure-flow studies offers a simple and reliable method for obtaining simultaneous pressure-flow values. It can be performed without further invasion in conjunction with cystometry. Therefore this technique is recommended in the urodynamic testing of male patients with lower urinary tract disorders.