Is catheter cause of subjectivity in sensations perceived during filling cystometry?

OBJECTIVES: To investigate the impact of the catheter on perceptions of filling. In our previous study, we demonstrated that some patients perceived sensations despite a lack of filling during cystometry.
METHODS: The study included 45 patients with lower urinary tract symptoms attributed to benign prostatic hyperplasia. The average patient age was 57.9 years (range 48 to 79). Patients were draped to keep them from seeing their penis and the filling bag, pump, and screen process. In the first phase, the catheter was fixed to the penile skin without introducing it through the urethra, and the patient was told the test had begun. At the end of the first phase, the bladder was emptied. Before the second phase, an 8F urodynamic catheter was introduced, but during the test, nothing was infused. During the third phase, filling cystometry was performed with a 50-mL/min pump speed. The bladder was emptied after all three phases. The times that elapsed until each sensation was perceived, in seconds, were used to compare the sensations.
RESULTS: In the first phase, 21 patients reported a first sensation, 10 reported first desire, and 4 reported normal desire, despite a lack of catheterization. No statistically significant difference was found between the mean first sensation/first desire, first sensation/normal desire, first desire/normal desire ratios of the patients who perceived sensations in the three phases and the strong desire/normal desire ratios of the patients in the second and third phases (P >0.05 for all).
CONCLUSIONS: Although the perceptions were reported in the first and second phases, the catheter could not be the sole cause of the subjectivity.