Hypothesis / aims of study
Cystoceles can be classified based on the functional anatomy of the bladder neck and proximal urethra. The two main types of cystoceles by Green’s classification are type II cystocele, i.e. a cystourethrocele, where the retrovesical angle (RVA) opens up during Valsalva manoeuvre, and type III cystocele, i.e. a cystocele with intact retrovesical RVA. [1] (see figure 1) Type II cystocele is associated with stress urinary incontinence (SUI), whereas type III seems to protect from SUI but predisposes to voiding dysfunction. [2]
Some women develop SUI symptoms after pelvic organ prolapse repair. Commonly the risk of de novo SUI is assessed preoperatively by performing stress testing on prolapse reduction. SUI presenting only during reduction of co-existing prolapse is termed occult SUI. The mechanism explaining occult SUI is not thoroughly understood, but it is believed that bladder base descent causes urethral obstruction due to kinking of the urethra. Consequently, correction of prolapse is thought to relieve the kinking, and the underlying compromised urethral closure mechanism becomes evident.
The aim of this study was to understand the mechanisms behind occult SUI. We hypothesized that type III cystocele and advanced cystocele are more common among women with occult SUI when compared with women who are symptomatic for SUI (overt SUI).
Study design, materials and methods
We conducted a cross-sectional study on patients evaluated for pelvic floor dysfunction at a tertiary urodynamic clinic between July 2016 and November 2018. Participants were assessed by standardized interview, clinical examination (Pelvic Organ Prolapse Quantification (POP-Q)), multichannel urodynamic testing and 4D translabial ultrasound. Translabial ultrasound was used to determine RVA, urethral rotation and organ descent relative to the inferoposterior symphyseal margin during maximal Valsalva [2]. We categorized cystocele using Green’s classification [1]: type II (cystourethrocele): RVA ≥140° and urethral rotation of 45-120°, and type III (cystocele with intact RVA): RVA <140° and urethral rotation of 45° or more (figure1). This definition was used on women demonstrating a significant cystocele on imaging, i.e. bladder descent to ≥10mm below the symphysis pubis [3]. Type I cystocele was excluded from analysis due to its relative rarity, and since it often seems to be iatrogenic, such as after anterior repair.
Only women with urodynamic stress incontinence (USI) were included; those after previous anti-incontinence surgery were excluded. We compared the women who were symptomatic for stress urinary incontinence (overt SUI) with those who were not (occult SUI), both for demographic characteristics, urodynamic findings as well as for functional anatomy, as defined by clinical examination and 4D translabial ultrasound. Associations were evaluated using univariate logistic regression. We then created a multivariable logistic regression model including significant predictors from univariate analysis. For regression analysis, cystocele type was categorized as no cystocele, type II cystocele, or type III cystocele.
Results
878 patients were seen during the inclusion period. Mean age was 58 years (SD 14), mean BMI 29 kg/m2 (SD 6) and median parity 2 (range 0-9). 263 (30%) participants had a history of hysterectomy, 155 (18%) of prolapse surgery and 111 (13%) of anti-incontinence surgery. 630 (72%) reported stress urinary incontinence, 605 (69%) urge urinary incontinence, 461 (53%) prolapse symptoms and 306 (35%) voiding dysfunction. After exclusion of women with previous anti-incontinence surgery, we were left with 767 patients. Of those, USI was seen in 458 (60%) participants; 390 (85%) were overt SUI and 68 (15%) occult SUI.
Of those 458 USI-positive women, 144 (31%) had a significant cystocele on imaging; 57 (40%) were classified as type II, and 80 (56%) as type III, and 7 (5%) other (two type I, 3 unclassified, 2 missing data). In univariate analysis, older age, higher BMI, slower maximum flow rate, higher values for Ba, C and Bp, greater bladder descent on imaging and type III cystocele were all associated with occult SUI. (see table 1) In multivariable regression model, statistically significant associations remained only for age and cystocele type. (table 1)
Interpretation of results
Cystocele type rather than its size, predicts occult SUI. In type III cystocele, prolapse reduction often exposes occult SUI. If patients present with type II cystocele, occult SUI appears unlikely.