Effect of Different Sized Transurethral Catheters on Pressure-Flow Studies in Women with Lower Urinary Tract Symptoms

Abstract

Introduction: The study evaluates the impact of three different sized (4.5-, 6- and 7-Fr) catheters on pressure-flow studies in women undergoing urodynamic evaluation for lower urinary tract symptoms. Material and Methods: 60 women referred for the evaluation of lower urinary tract symptoms were enrolled in this randomized controlled study. Patients were divided into two groups (A and B) of 30 women each. The patients underwent non-invasive free-flow uroflowmetry with determination of post-void residual urine volume (PVR) and two consecutive pressure-flow studies using two different transurethral catheters. In group A the two consecutive pressure-flow studies were performed using a 4.5-Fr catheter once and a 6-Fr catheter once; in group B the two consecutive pressure-flow studies were performed using a 4.5-Fr catheter once and a 7-Fr catheter once. Patients were also randomized for the consecutive order in which the two different transurethral catheters were used. Results: The pressure-flow parameters were significantly different from the equivalent free-flow findings. The maximum and average flow rate in all pressure-flow studies performed were significantly lower than the equivalent free-flow parameters and the flow time was significantly longer for all pressure-flow versus free-flow studies. Furthermore, there was a significantly larger PVR for pressure-flow than for free-flow measurements. There was no significant difference in maximum flow rate, average flow rate and flow time between 4.5- and 6-Fr pressure-flow studies (group A). However, there was a statistically significant difference between 4.5- and 7-Fr pressure-flow studies (group B) in those uroflowmetry parameters. Detrusor pressure at maximum flow (P_det.Q_max) and maximum detrusor pressure (P_{det. max}) in group A did not show statistically significant differences between 4.5- and 6-Fr pressure-flow studies whereas in group B P_det.Q_max and P_{det. max} were significantly different between 4.5- and 7-Fr pressure-flow studies. Conclusions: A 4.5-, 6- or 7-Fr transurethral catheter may obstruct micturition changing uroflowmetry parameters. A statistically significant difference was found in all but PVR parameters particularly in all detrusor parameters between 4.5- vs. 7-Fr whereas no statistically significant difference was found in all but PVR parameters between 4.5- vs. 6-Fr. We can thus state that pressure-flow findings may be influenced by different sized transurethral catheters. A misinterpretation of pressure-flow findings may have clinical implications on establishing an accurate diagnosis.