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

OBJECTIVE: This study was undertaken to describe the effects of urethral pe rfusion on bladder activity, urethral pressure, and sensation in patients w ith either incontinence or prolapse or both of these. STUDY DESIGN: Among 76 consecutive patients who were seen for urodynamic ev aluations, 63 had vesical, abdominal, and urethral pressures measured while the urethra was perfused with fluid. A perfusion study result was consider ed positive if the perfusion provoked a detrusor contraction. RESULTS: Of the 63 women 9 (14%) had a positive urethral perfusion study re sult, and all of them had detrusor instability independent of perfusion. Am ong the women with detrusor instability 53% (n = 9/17) had positive study r esults, versus none of the 46 women without detrusor instability (P =.00000 1). Women with mixed incontinence were more likely to have a positive perfu sion test result (n = 4/7; 57%) than were those without mixed incontinence (n = 5/56; 10%; P=.006), although urethral hypermobility was not significan tly associated with a positive test result. Among the subjects 60% experien ced urgency during perfusion, and in half of these urethral pressure was co ncurrently increased. Among those who had no urgency 84% demonstrated decre ased urethral pressure (P=.01). CONCLUSIONS: Positive perfusion study results were more common among women with detrusor instability but did not discriminate any patient with detruso r instability whose condition was not diagnosed by standard urodynamic stud ies. The association of positive perfusion study results with mixed inconti nence seems primarily related to poor central inhibition of detrusor activi ty rather than to urethral stimulation.