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.

The effect of a 6 Fr catheter in women: Are they obstructive?

“…21 Interestingly, Scaldazza and Morosetti have also confirmed that the use of smaller catheters (4.5 Fr) resulted in a decrease P det Q max in comparison to bigger ones (7 Fr). 16 This effect on the P det Q max has also been studied in men by Zhao and colleagues. 22 These authors concluded that the use suprapubic catheters lowered the P det Q max by more than 10 cmH 2 0 in comparison of transurethral catheters.…”

“…15 This was confirmed by Scaldazza and Morosetti. 16 They evaluated the impact of 3 different sized catheters (4.5, 6 and 7 Fr). They demonstrated that all 3 may obstruct micturition.…”

“…Other explanations are a decrease in urethral compliance, 23 an individual normal variation of flow pattern between studies and an "artificial" voiding pattern created by the procedure 16 (possibly related to numerous other factors, including supraphysiological filling rate, psychogenic inhibition and incomplete relaxation of the external sphincter due to the presence of a foreign material in the urethra). 24 Valentini and colleagues also recently suggested that the lowering of the Q max might be due a break in the detrusor excitation or a compression-like effect due to a urethral reflex.…”

Differences in urodynamic voiding variables recorded by conventional cystometry and ambulatory monitoring in symptomatic women

“…The higher values for Q max seen with AMB (on average 33%) might be explained at least partially by the presence of both 4Fr and 10Fr urethral catheters during CONV. Some evidence in support of this contention comes from intra-individual comparison of Q max with and without the presence of a urodynamic measurement catheter with studies in healthy (12) and symptomatic women (13)(14)(15) showing relative differences of between 28% and 64% using 6Fr, 7Fr and 9Fr catheters.…”

Differences between the data from free flow and intubated flow in women with urinary incontinence. What do they mean?

“…The transurethral catheter used to fill the bladder and to record the pressure may produce some effects on the physiology of voiding: irritative effect, bladder outlet obstruction. These potential effects have been few studied in women; [1][2][3][4][5] in addition the findings are controversial.…”