Urodynamic Changes Associated with Successful Stress Urinary Incontinence Surgery: A Little Tension is a Good Thing?

 

Introduction and Objectives

The aim of this study is to identify urodynamic changes that correlate with overall success after stress urinary incontinence surgery.

Methods

This analysis uses data from 655 women randomized to Burch colposuspenion or autologous fascial sling as part of the multi-center Stress Incontinence Treatment Efficacy Trial. Prior to and 24 months after surgery, all women underwent standardized urodynamic studies (UDS) that included non-invasive uroflow (NIF), cystometrogram (CMG) and pressure flow studies. UDS parameters are listed in Table 1. Bladder outlet obstruction index (BOOI) was calculated based on the formula BOOI = PdetQmax - 2Qmax. Overall success required a negative pad test, no urinary incontinence on 3-day diary, a negative cough and valsalva stress test, no self-reported incontinence symptoms on the Medical, Epidemiological and Social Aspects of Aging Questionnaire (MESA), and no re-treatment. Data are reported on those women with analyzable UDS at both time points and a known outcome status. Linear models were fit to assess change in UDS measures from baseline to 24 months in relation to success status, controlling for treatment group. Contingency tables were constructed for categorical measures; Mantel-Haenszel tests were used to assess relationships with success.

Results

Table 1 reports the urodynamic changes over 24 months based on success and failure status as well as type of surgery. Participants with overall success in each surgical arm demonstrated a greater increase in mean Pdet Qmax between baseline and 24 months compared with failures. There were no differences with regards to: maximum flow, compliance, preoperative DO or de novo DO. A reduction in MCC was seen in Burch successes while those who failed had an increase in MCC. The inverse was seen with the sling success/failures.

Conclusions

In this subgroup of women, overall surgical success was associated with greater increases in voiding pressures following both Burch and sling procedures compared to patients who failed. Since detrusor voiding pressure is a product of detrusor contractile force and outlet resistance and since it is unlikely that contractile force was altered, our results suggest that surgical success is associated with increased outlet resistance (Figure 1).

Keywords

urodynamics, stress urinary incontinence, sling

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