Hypothesis / aims of study
The relationship between anterior vaginal compartment prolapse and overactive bladder (OAB) symptoms has been stablished in the literature, but data correlating the severity of prolapse with these symptoms are very sparse (1). Published studies only consider the most advanced point of anterior prolapse and do not assess its relationship with urethral position. The anatomy of anterior wall prolapse is defined not only by the most descended point, but also by the possibility of urethral kinging. The Pelvic Organ Quantification (POPQ) system allow us to describe anterior vaginal wall prolapse more correctly. Using both anterior compartment points, we can identify if the is any degree of kinking in the urethra. Obviously, when point Aa reach maximum descent (+3) there is no possibility of kinking, even if point Ba has a greater value. A smaller descent of point Aa combined with a greater one of point Ba raises the possibility of urethral kinking.
The aim of the study was to evaluate if there is any relationship between anterior vaginal compartment anatomy and OAB symptoms in women with prolapse. Our hypothesis is that both urethral kinking and large anterior vaginal compartment prolapse could be associated with an increased risk of OAB.
Study design, materials and methods
This was a cross-sectional multicentre study including all women with symptomatic anterior compartment prolapse that were evaluated in the pelvic floor units of two different hospitals between May 2015 and September 2017 prior to surgery. Pelvic organ prolapse was described according to the POPQ system. Two gynecologists blinded to symptoms reports performed the examination. Urethral kinking was defined when point Aa was less than + 3 and at least 2 cm higher than point Ba. Symptoms of prolapse and urgency urinary incontinence (UUI) were identified using the validated Spanish version of the Pelvic Floor Distress Inventory short form (PFDI-20). Urinary urgency was identified using the first question of the validated Spanish version of the Bladder Control Self-assessment Questionnaire (B-SAQ). Statistical analysis was done by proportion comparison (Chi-square) and multivariate analysis (multiple logistic regression model).
We included 481 patients with symptomatic anterior compartment prolapse scheduled for surgery. Mean age was 63.2 years (SD:9.7; range:37-86) and mean body mass index (BMI) was 29.8 (SD:5.7; range:16.8-70.4). Of these, 251 (52.2%) reported urinary urgency in the B-SAQ questionnaire and 191 (39.7%) reported UUI in the PFDI-20 questionnaire. Examination of the anterior compartment indicated POPQ stage 2 in 93 (19.3%) patients, stage 3 in 345 (71.7%), stage 4 in 43 (8.9%), and urethral kinking in 173 (36.0%) patients. Maximum urethral descent (point Aa +3) was identified in 86 (17.9%) women. Prolapse examination also identified POPQ stage ≥ 2 in 259 (53.8%) women in the apical compartment and in 157 (32.6%) in the posterior compartment.
The evaluation of the association between urethral kinking and OAB symptoms indicated that patients with this anatomical finding were at greater risk of presenting urinary urgency (OR: 2.29; 95% CI: 1.46-3.57). Patients with urethral kinging were also more at risk for UUI (OR: 1.85; 95% CI: 1.23-2.79). These analyses were adjusted by age, BMI and prolapse in the others compartments as potential confounders (table 1). Maximum anterior prolapse (POPQ stage 4) when compared with POPQ stage 2 was also associated with an increased risk of both OAB (OR: 6.52; 95% CI: 2.43-17.46) and IUU (OR: 3.57; 95% CI: 1.53-8.30): These analyses were also adjusted for potential confounders.
Interpretation of results
The pathophysiology of OAB in women with pelvic organ prolapse is still unclear and different theories have been hypothesized (2). Prolapse can cause bladder outlet obstruction, being the most accepted mechanism for developing OAB. Our result shows that patients with some degree of bladder obstruction, represented by urethral kinking, are at greater risk for OAB. Alternatively, two more theories seek to explain the association between large anterior compartment prolapse and OAB. The release of chemical factors due to bladder distension, and urine entering the urethra, open due to traction from a prominent cystocele. Our results also show that women with large anterior vaginal prolapse are more at risk for OAB. Probably, a combination of different pathophysiology mechanisms is necessary to explain the relationship between anterior vaginal prolapse and OAB.