Pelvic organ prolapse (POP) is an anatomical change of female pelvic floor referring to a falling, slipping or downward displacement of a pelvic organ. Uterus, bladder, rectum, or bowel could be clinically found displaced inside vaginal compartments, often causing lower urinary tract dysfunction (LUTD), not always noticeable by patients. The main reason that leads women to a physician, urologist, or urogynecologist, is the feeling of something prolapsing and sometimes palpable between legs, whereas urinary incontinence or dysfunctional voiding could also reveal a background of POP during clinical examination. Staging of POP had been a challenging subject of argument in the past, until the Staging System of Quantitative Pelvic Organ Prolapse (POP-Q) System was introduced and labelled as an ideal instrument for evaluation of prolapse in everyday clinical practice. The aim of our study is correlate the LUTD with the underlying stage of POP.

This is an observational prospective study including female patients above the age of 18, pooled both from the Urodynamics Clinic of the Urology Department and the Department of Obstetrics and Gynecology of our Hospital. The study has been approved by the Local Ethical Committee and all participants have signed a consent form at the enrollment visit. The prolapse has been evaluated with the Staging System of Quantitative Pelvic Organ Prolapse (POP-Q) System.
The inclusion criteria encompassed all women with a clinical POP, regardless of documentation of any lower urinary tract symptoms (LUTS). Patients with a previous pelvic surgical or conservative intervention for prolapse or LUTD, any kind of pelvic organ malignancy, neurological disorders, soft tissue diseases, affected upper urinary tract, and those with a vaginal ring or under medication for LUTD were excluded. Women were allocated in four Groups depending on the stage of the diagnosed prolapse and underwent an invasive urodynamics study (UDS) under the standards of the International Continence Society (ICS) for the evaluation of the lower urinary tract function. Prior to UDS, all patients had a bladder scan and post void residual (PVR) measurement, a stress test along with a free uroflow. The correlated parameters were the stage of POP and the time since it has been detected with any kind of clinical LUTD, maximum flow rate (Qmax) in uroflow and urodynamic findings such as detrusor overactivity (DO), urodynamic incontinence, maximum bladder capacity (MBC), bladder compliance, bladder outlet obstruction (BOO) and bladder contractility. 
BOO has been evaluated according to the Blaivas-Groutz (B-G) nomogram, while bladder contractility has been calculated with the Bladder Contractility Index (BCI) formula [detrusor pressure at Qmax (PdetQmax) + 5Qmax]. Additionally, prolapse detected since less than 1 year has been defined as T1, between 1-5 years as T2 and more than 5 years as T3 group.
Data were collected and statistically analyzed with SPSS v26 (IBM Corp. Released 2019. IBM SPSS Statistics for Windows, Version 26.0. Armonk, NY: IBM Corp).

From the total of 102 patients initially enrolled, 96 completed the study with a median age of 67 years (range 54-83). Among the 6 dropout patients, 4 of them did not complete the urodynamic evaluation and 2 of them denied invasive urodynamics beforehand. Considering the kind of prolapse, 43 (44.8%) of women had cystocele, 47 had uterine prolapse (48.9%), 1 had rectocele (1.1%) and 5 (5.2%) suffered from total prolapse. Regarding the stage of prolapse, 29 (30.2%) of the women were classified as Stage I, 46 (47.9%) as Stage II, 14 (14.6%) as Stage III and 7 (7.3%) as Stage IV POP. 77 (80.2%) patients reported LUTS, with the 49 (63.6%) of them complaining about urinary incontinence and 28 (36.4%) about difficult voiding. Stress test was positive in 44 (45.8%) women, the median PVR was 140ml (range 0-320), the median MBC was 360ml (range 120-480) and the median Qmax was 17ml/sec (range 6-28). There were no patients with affected bladder compliance.
Urodynamic findings for Stage I patients were detrusor overactivity (DO) in 10 (34.5%) of them without any kind of urodynamic incontinence, while none had BOO or detrusor underactivity (DU), and all were allocated at group T1. 21 (45.7%) Stage II patients had DO and in 5 (23.8%) of them it was followed by urine leakage, while 6 (13%) had BOO according to B-G nomogram but none had DU. 14 patients (30.4%), including those 6 with BOO, where assigned in group T2, while the rest 32 (69.6%) in group T1. 6 (42.9%) Stage III patients had DO accompanied by urine leakage during UDS, 11 (78.6%) were found with BOO and 2 (14.3%) with DU. 6 (42.9%) of those patients were in group T2 and 8 (57.1%), including those 2 with DU, were in group T3. Finally, all 7 Stage IV women were placed in group T3 and all had DO without urodynamic urine leakage, 4 (57.1%) of them had BOO and 3 (42.9%) of them DU.

Considering the results of our observational prospective study, we suggest that there could be two separate factors correlating POP with the dysfunction of the lower urinary tract.
The first one is the prolapse stage, noticing that the heavier the stage of prolapse is, the more severe the LUTD could be. For patients in stage I, only urodynamic findings of DO were observed with no clinical evidence of LUTS at all, while in stage II the main symptom seems to be urinary incontinence, with only a few cases of voiding dysfunction. On the other side, in stages III and IV LUTD appears to be more significant, including filling and voiding symptoms, confirmed mostly by UDS.
The second factor associating POP with LUTD could be the elapsed time since the diagnosis of prolapse. Looking throughout the results of our study, we could suggest that the more neglected prolapses are more possible to lead to urodynamic findings and LUTS. Combining both factors, prolonged and heavy prolapses could cause more severe LUTD.
There are two limitations regarding our study. First of all, the urodynamic formula for bladder contractility is not well established for female patients and sometimes urodynamic pattern was more suitable to diagnose DU than BCI itself. Another one, could be that the time of POP diagnosis, especially for the most neglected cases, was not always as precise it should be.

Pelvic organ prolapse is directly associated with any kind of LUTD. More severe or delayed in diagnosis prolapses could lead to more complicated types of LUTS. Thus, timely diagnosis and treatment of POP could be crucial for the preservation of lower urinary tract functional integrity.

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