Overactive bladder (OAB) is common among women with pelvic organ prolapse (POP) but the pathophysiology of this association is still unknown. There is an improvement of OAB after prolapse surgery, however symptoms do not disappear in all cases. It is unclear whether the OAB symptoms will remain or not after surgery (1). The aim of this study was to evaluate the influence of prolapse stage in the presence of OAB, and its resolution after anterior prolapse repair. Our study hypothesis was that the increased structural damage present in severe anterior prolapse could be associated with more initial symptoms and less chance of resolution after surgery.

This was a prospective multicentre study including all women with symptomatic anterior compartment prolapse that were scheduled for surgery in the pelvic floor units of two different hospitals between May 2015 and September 2017. Those women who finally did not have surgery were excluded. Other exclusion criteria were prior POP surgery, use of meshes in POP surgery, concomitant surgery for SUI, and patients unable to complete questionnaires. 
Pelvic organ prolapse was described according to the Pelvic Organ Prolapse Quantification (POPQ) system. Two gynecologists blinded to symptoms reports performed the prolapse examination. At inclusion and one year after surgery, urgency and urgency urinary incontinence (UUI) were identified using the specific questions of the validated Spanish versions of the Bladder Control Self-Assessment Questionnaire (B-SAQ) and Pelvic Floor Distress Inventory short form (PFDI-20) respectively.
Correlation of preoperative prolapse POPQ stage with urinary urgency at baseline visit, and one year after surgery, were examined by multiple logistic regression models including age as potential confounder. Statistical significance was set as p=0.05.

We recruit 377 patients with symptomatic anterior compartment prolapse that underwent primary vaginal surgery during the inclusion period. One year after surgery 367 (97.3%) attended the follow up visit and formed the study group.
Mean age was 63.2 years (SD:9.7; range:37-84) and mean body mass index (BMI) was 29.5 kg/m2 (SD:5.4; range:16.8-49.5). Age was categorized as <60 years: 128 (34.9%); 60-69 years: 141 (38.4%) and ≥ 70 years: 98 (26.9%). At inclusion 197 (53.6%) women referred urgency, and 145 (39.5%) UUI. The distribution of urgency related to prolapse stage in the anterior compartment, and categorized age is shown in table 1. Patients with POPQ stage 3 or 4 were more at risk of having OAB as compared with stage 2 in the baseline visit.  Increased risk adjusted with age were OR:4.33 for stage 3 and OR:12.90 for stage 4. Age was also an independent risk factor for baseline urgency. 
One year after surgery 121 (33.0%) women referred urgency and 63 (17.2%) UUI. Of those 18 (10.6%) and 12 (7.1%) were new cases of urgency and UUI respectively. The remaining 103 (52.3%) and 51 (25.9%) persisted with urgency and UUI from baseline visit. The distribution of persistent urgency according to preoperative POP stage in shown in table 1. Patients with stage 3 or 4 in the anterior compartment were more at risk of persisting with urgency as compared with stage 2.  Increased risk adjusted with age were OR:3.85 for stage 3, and OR:5.59 for stage 4. Age ≥ 70 was also an independent factor for the persistence of OAB.

The pathophysiology of OAB in women with pelvic organ prolapse is still unclear and different theories have been hypothesized. Prolapse can cause bladder outlet obstruction, being the most accepted mechanism for developing OAB. The stretching of receptors in the urothelium due to bladder distension and the opening urethra secondary to traction from a prominent cystocele are also mechanisms that have been proposed (1). Women with severe anterior compartment prolapse were more at risk not only for baseline OAB, but also for persisting with urgency one year after surgery. The risk of persisting with urgency was as high as 4.0 for stage 3, and 5.7 for 
stage 4. Greater structural damage in the pelvic floor tissues of these patients could justify both results. Which of the three mechanisms described above participate in OAB related to POP, and its resolution after surgery is yet to be established. 
As expected, our results also indicate that older women with POP are more at risk for OAB at baseline and after prolapse surgery. Age-related changes in the bladder and pelvic floor tissues and/or in the nervous system contribute to the high prevalence of OAB in elderly women (2). These permanent changes could justify the high prevalence of OAB among the elderly (70.4%) and its high persistence after POP surgery (OR:5.59).

POPQ stage ≥ 3 and age ≥ 60 years increased the risk of urgency in women with symptomatic anterior compartment prolapse. This increase is higher in POPQ stage 4 and age ≥ 70 years. Close to half of patients with OAB experience improvement of urgency one year after surgery, although those who had a preoperative POPQ stage ≥ 3 or age ≥ 70 may be at higher risk of persist with urinary urgency. This information may be useful to advise women with OAB undergoing POP surgery regarding postoperative expectations.

De Boer et al. Pelvic organ prolapse and overactive badder. Neurourol Urodyn 2010; 29(1):30-39.
Zhu J, Hu X, Dong X, Li L. Associations Between Risk Factors and Overactive Bladder: A Meta-analysis Female Pelvic Med Reconstr Surg 2019;25: 238–246.