DOES URETHRAL BLOOD FLOW CORRELATE WITH URETHRAL CLOSURE PRESSURES OR SYMPTOMS OF URINARY INCONTINENCE IN INCONTINENT WOMEN?

R. Hall, S. Khalsa, C. Qualls, R. Rogers

University of New Mexico, Albuquerque, NM

OBJECTIVE:  To correlate Doppler resistive indices (RI) with maximum urethral closure pressures (MUCP) and Incontinence Impact Questionnaire-7 (IIQ-7) scores in women with stress urinary incontinence.

MATERIALS ANDMETHODS: Human research approval was obtained for this prospective cohort study.  Women with stress urinary incontinence were recruited from the urogynecology clinic.   Spectral Doppler waveform analysis assessing of periurethral vasculature was performed using a 4-8 MHZ curvilinear endovaginal transducer (ATL 5000; Bothell, WA).  Three waveforms were obtained; the median calculated RI chosen for the representative waveform.  RI measures peak systolic velocity minus end diastolic velocity divided by peak systolic velocity and represents resistance to blood flow.  Urethral morphology was also recorded.  Two MUCP’s were obtained using a 7 French microtip catheter with a pull through technique with the bladder filled to 200-250 cc’s.  Each measurement was made twice. Women completed demographic questionnaires as well as the IIQ-7 to assess impact of stress incontinence on social functioning.  Descriptive statistics (means, standard deviations, proportions) were used to describe the overall study population.  Correlation coefficients were calculated for comparisons of Doppler measurements and closure pressures, IIQ-7 scores and urethral morphology measurements.  T tests were used to analyze differences between measurements and demographic variables between RI and MUCP. Fifty patients were required to detect a difference between no correlation and a modest correlation of. .38 with 80% power and alpha of .05.  Significance is set at p<.05. 

RESULTS:  Fifty nine patients consented for participation.  Incomplete data were available for eight women.  Mean age of patients was 53.2 years (SD=11.3), vaginal parity 3.6 (SD= 2.6), body mass index (BMI) 29.0 kg/m2 (SD=6.4), and all women complained of stress predominant urinary incontinence.  Thirty-three/51 (64%) women had anterior wall prolapse to or beyond the hymen.  Measurements were reproducible between Doppler waveforms (all t < 2.0, df >51, p=NS) and MUCP measurements (paired t test (46) = .24, p= NS).  Median RI was 0.76 (range .45 to 1.0).   RI was not correlated with age, parity, MUCP, IIQ-7 scores, urethral length or urethral width. (All r< .11, df > 51, and p= NS). RI and MUCP were likewise not associated with history of diabetes, hypertension or anterior vaginal wall prolapse to or beyond the hymen.  (All paired t tests < 2.44, df > 40, p = NS)  MUCP was negatively correlated with age (r = -0.36, df >54, p = 0.007) even when controlled for hormonal status (ANCOVA, p=.003).

CONCLUSION: Resistance to urethral blood flow does not correlate with maximal urethral closure pressure or IIQ-7 scores.

Key Words: urethral blood flow, urinary incontinence

Disclosure –Grant/Research: R. Rogers, Pfizer, Wyeth-Ayerst; Educational Support: R. Rogers, Yamanouchi Pharma America, Proctor & Gamble.