The urethrodetrusor facilitative reflex in women: Results of urethral perfusion studies

OBJECTIVE: This study was undertaken to describe the effects of urethral perfusion on bladder activity, urethral pressure, and sensation in patients with either incontinence or prolapse or both of these. STUDY DESIGN: Among 76 consecutive patients who were seen for urodynamic evaluations, 63 had vesical, abdominal, and urethral pressures measured while the urethra was perfused with fluid. A perfusion study result was considered positive if the perfusion provoked a detrusor contraction. RESULTS: Of the 63 women 9 (14%) had a positive urethral perfusion study result, and all of them had detrusor instability independent of perfusion. Among the women with detrusor instability 53% (n = 9/17) had positive study results, versus none of the 46 women without detrusor instability (P =.000001). Women with mixed incontinence were more likely to have a positive perfusion test result (n = 4/7; 57%) than were those without mixed incontinence (n = 5/56; 10%; P=.006), although urethral hypermobility was not significantly associated with a positive test result. Among the subjects 60% experienced urgency during perfusion, and in half of these urethral pressure was concurrently increased. Among those who had no urgency 84% demonstrated decreased urethral pressure (P=.01). CONCLUSIONS: Positive perfusion study results were more common among women with detrusor instability but did not discriminate any patient with detrusor instability whose condition was not diagnosed by standard urodynamic studies. The association of positive perfusion study results with mixed incontinence seems primarily related to poor central inhibition of detrusor activity rather than to urethral stimulation.