Stress and Urgency Urinary Incontinence: Clinical-Urodynamic Correlation and Rehabilitation Management in Daily Clinical Practice

(a) To correlate the clinical with the urodynamic diagnosis in a series of patients with UUI (urgency urinary incontinence) and SUI (stress urinary incontinence); (b) establish age, clinical and urodynamic differences; and (c) demonstrate the effectiveness of individualized rehabilitation treatment based on the clinical-urodynamic diagnosis in patients with SUI and UUI in the daily clinical practice of a third-level rehabilitation service. Retrospective study of 60 patients with SUI and UUI. Urodynamic study: (a) free flowmetry; (b) filling cystomanometry; (c) pressure-flow study. Outcome variables: daytime (DUF) and nighttime (NUF) urinary frequency, strength of the pelvic floor muscles (PFM) measured by manometry (maximum and mean pressure), and use of absorbents/day. Rehabilitation treatment: (a) pelvic floor muscle training (PFMT); (b) biofeedback (BFB), transcutaneous neuromodulation of the posterior tibial nerve (TTNM). Age, clinical, and urodynamic differences have been observed between patients with UUI versus SUI. UUI is more frequent in older patients (UUI 67.3 ± 10.19 years vs SUI 58.6 ± 8.54 years), p = 0.0028. Patients with UUI, when compared with patients with SUI, present more episodes of DUF (7.7 ± 5.1 vs 5.5 ± 3.99) and NUF (2.51 ± 1.67 vs 1.46 ± 1.42). Patients with SUI use more absorbents/day than patients with UUI (2.7 ± 1.53 vs 1.37 ± 1.5), p = 0.0243. The urodynamic study (UDS) confirmed the clinical diagnosis in UUI in 64.7%, while in SUI, it was only confirmed in 35.1%. In the urodynamic analysis (free flowmetry), patients with UUI have smaller bladders than patients with SUI (voiding volume in UUI 275.8 ± 178.95 vs 411.03 ± 203.62 in SUI), p = 0.083. The maximum flow (Qmax) is higher in patients with SUI compared to UUI (19.6 ± 7.07 vs 16.06 ± 8.54), p = 0.0836. In filling cystomanometry, the bladders of patients with UUI are smaller than those with SUI (bladder capacity UUI 266.3 ± 52.76 vs 308.6 ± 49.72 ml in SUI), p = 0.023. In SUI, the BFB/PFMT significantly improved DUF, NUF, PFM pressure, and absorbent use. In UUI, the BFB plus TTNM improved DUF, NUF, and the maximum and mean PFM pressure with statistical difference, while the use of absorbents decreased with a tendency to significance. There are age, clinical, manometric, and urodynamic differences in patients with UUI when compared with patients with SUI. UUI occurs in older patients; they present a greater number of daytime and nocturnal urinary frequency episodes and use fewer absorbents than patients with SUI. Patients with UUI evacuate a smaller urine volume have a lower peak flow (in flowmetry) and a lower bladder capacity (in cystomanometry) than patients with SUI. The rehabilitation treatment proposed in daily clinical practice (PFMT/BFB with or without TTNM improves SUI and UUI). In this study, the UDS has shown a greater clinical-urodynamic correlation in UUI than in SUI.


Introduction
Urinary incontinence (UI) is currently defined as any urine leakage capable of producing a social or hygiene problem [1]. The impact of urine leakage is such that it is believed to affect quality of life (QOL) more than prevalent diseases such as diabetes mellitus or arterial hypertension [2]. The This article is part of theTopical Collection on Medicine impact on health and the economy is important, since nearly 1.7 million men and 4 million women suffer from UI in Spain [2].
UI can be defined according to the precipitating symptoms in the following: (1) stress UI (SUI), which occurs after efforts (coughing, sneezing, laughing); (2) urgency UI (UI), the involuntary loss accompanied or preceded by emergency; and (3) mixed UI (MI), the loss associated with effort and urgency [3]. According to severity, SUI can be classified in degrees, according to the O'Brink Scale, in the following: (a) mild (loss after coughing or sneezing); (b) moderate (loss after walking or picking up weights); and (c) severe (loss at rest) [4]. The aim of characterizing UI is fundamental, since the treatment must be directed towards the main concern (loss, urgency or both); in fact, the treatment algorithms have been created with that objective [3].
However, no test is capable of diagnosing UI with 100% accuracy. The physical exam does not differentiate the type of UI. The medical history per se is not capable of being adequately interpreted in patients with UI. For this reason, standardized scales such as questionnaires (ICIQ-SF, IQoL, OAB-q) or the voiding diary can help to resolve such discrepancies [5]. Therefore, the diagnosis of UI should be made with (1) history and physical examination, (2) urine culture and analysis, (3) voiding diary, (4) pad test/24 h (pad test), and (5) urodynamic study that includes (a) free flowmetry, (b) filling cystomanometry, and (c) pressure-flow study [6].
The urodynamic study (UDS) is an extension of the medical history and physical examination, but in a nonphysiological way. The UDS increases the understanding of the function of the lower urinary tract (LUT) and reveals the underlying pathology that causes the discomfort to the patient [7]. In this sense, the UDS tries to measure different physiological variables and therefore is an instrumental or artificial test to assess the role of the LUT [6]. The UDS thus provides the most detailed and available information regarding the incontinence condition, and in many settings, the UDS is essential to provide adequate care [5].
The UDS measures bladder pressure and urinary flow during the bladder filling and emptying phase to assess neuromuscular function and LUT function, in order to identify the causes of bladder filling and emptying dysfunction [8]. However, the accuracy of the UDS has never been studied because there is no standard reference test that assesses the function of the LUT [9]. In fact, Okorocha has surprisingly suggested that the UDS should be validated by a randomized controlled study although it has never been required to other tests such demands to prove their validity, being therefore impractical and unethical [10].
Despite the above considerations, the value of the UDS in the evaluation of patients with UI is controversial. Some authors question that UDS provide useful data in the disorders of the LUT. These authors maintain that a detailed medical history and physical examination are capable of providing an adequate diagnosis in most cases [8]. Others have even noted inconsistency between clinical and urodynamic diagnosis in a significant number of patients [8,11].
In the evaluation of UI, the objective of the UDS is to objectively demonstrate UI and differentiate it from the different existing types (SUI, UUI, MUI), in order to apply the most effective and appropriate treatment [8]. However, there is little evidence to support this approach; that is, that urodynamic diagnosis improves clinical outcomes, or that the UDS predicts which patients will be cured after surgery due to SUI, or which patients will develop overactive bladder [8]. Therefore, the usefulness of the UDS is yet to be determined.
The objectives of this article are as follows: (a) to correlate the clinical with the urodynamic diagnosis in a series of patients with UUI and SUI; (b) establish age, clinical and urodynamic differences (if any); and (c) demonstrate the effectiveness of individualized rehabilitation treatment based on the clinical-urodynamic classification in patients with SUI and UUI in the daily clinical practice of a thirdlevel rehabilitation service.
The zero hypotheses is that there is no clinical, manometric, urodynamic, and age differences between patients with different types of urinary incontinence. The alternative hypotheses is that there are clinical, manometric, urodynamic, and age differences between patients with different types of urinary incontinence.

Material and Methods
We have retrospectively evaluated 60 female patients diagnosed with UI (30 patients with SUI, and 30 patients with UUI), referred to the rehabilitation service at Santa Cristina University Hospital, from January to December 2019. This study has been authorized by the Committee of Ethics of the Hospital and also complies with the clinical guidelines existing at the date of the study for the management of UI [1,2,4,12,13].
The inclusion criteria were the following: (1) female patients over 18 years of age; (2) with symptoms of urine leakage, urgency, or both; (3) clinical and manometric evaluation; (4) urodynamic diagnosis; (5) signed consent for rehabilitation treatment and for management of clinical data; (6) failure to pharmacological treatment (anticholinergics, β3 agonists, or others).
Exclusion criteria were as follows: (1) lack of cooperation or abandonment of treatment; (2) lack of understanding to carry out the treatment; (3) any serious neurological condition that makes it impossible to produce voluntary contractions of the pelvic floor muscles (PFM), such as stroke, dementia, and spinal cord injury; (4) presence of pacemaker or sacral neurostimmulator that contraindicates the use of peripheral neuromodulation.
In the initial evaluation, personal data (age), clinical data (daytime urinary frequency [DUF], nighttime urinary frequency [NUF]), manometric evaluation, and urodynamic data were recorded. The use of absorbents/day was also recorded (pad test/24 h). A clinical-urodynamic correlation was made, checking both diagnoses according to the type of UI.
In the final evaluation, the clinical and manometric variables were recorded after carrying out the proposed treatment (SUI or UUI).
The proposed protocol according to clinical guidelines varied in terms of symptoms or diagnosis of UI (SUI, UUI, MUI) [1,2,4,12,13]. In the case of UUI, the most used treatment was BFB plus transcutaneous neuromodulation of the posterior tibial nerve (TTNM) and the number of sessions proposed was 8, while in the case of SUI, the proposed treatment was PFMT with/without BFB and in some cases with mixed symptoms, TTNM, in a number of 6 sessions.
The outcome variables were the use of absorbents per day (pad test/24 h), the number of episodes of DUF (normal < 8/ day), of NUF (normal < 2/day), and the PFM strength measured as maximum and mean pressure, evaluated with the MYOMED® 932 equipment (ENRAF-NONIUS B. V., PO Box 810, NL-2600 Av Delft, Hetherlands).
For the evaluation of PFM strength, a continuous manometric evaluation of 2 min was carried out (tonic exercises for one minute and phasic exercises for another minute), in order to obtain the maximum and average contraction of the session. These values are an effective way to demonstrate the strengthening of the PFM over time (before and after treatment).
The manometric BFB protocol consisted of a 30-min session of PFM contractions divided into 15 min of tonic exercises (5 s of contraction plus 5 s of rest) and 15 min of phasic exercises (5 rapid contractions followed by 10 s of rest), supervised by a physiotherapist, 2 times/week until the proposed treatment is completed (6 sessions in SUI, 8 sessions in UUI) [1,12,14]. To perform the contractions, a vaginal probe connected to the MYOMED® 932 equipment was required.
TTNM was performed with the patient sitting or lying down, and the lower limb to be treated elevated. Two 50 × 50-mm surface electrodes were used, one placed 5-cm proximal to the medial malleolus (on the posterior tibial nerve path), and the other electrode placed on the ipsilateral calcaneus. The TENStem eco basic equipment (Pierenkemper GmbH, Hoernsheimer Eck 19-355,678, Wetzlar, Germany) was used. The session time was 30 min, in which a symmetrical biphasic rectangular current was applied with an amplitude of 0 to 9 mA, a frequency of 20 Hz, and a pulse of 200 μs. The intensity of the current was regulated until a sensory sensation (tingling in the sole of the foot) or a motor sensation (plantar flexion of the 1st toe or fan opening of the fingers) was obtained [15].
The UDS was carried out at the urology service by a trained urologist and following the recommendations of the ICS (International Continence Society) [16,17]. The following procedures were performed: (1) non-invasive free uroflowmetry, which was performed privately, registering the voided voiding volume (normal from 0 to 1000 ml) and then the maximum voiding flow (Qmax [normal if > 15 ml/s]); (2) filling cystomanometry which was performed with a 6F double urovesical catheter for bladder measurement and filling; and another 8F rectal catheter with an inflatable balloon to measure abdominal pressure. The infusion rate was 50 ml/min. The stress maneuver was performed with 3 episodes of coughing with increasing intensity, in order to determine the loss of urine due to stress. The maximum cystometric capacity was determined (normal between 300 and 600 ml). Finally, the following was carried out: (3) pressure-flow study, in which the detrusor pressure and Qmax (normal > 15 ml/s) were measured. The appearance of detrusor contractions with an intensity > 20 cmH2 in the absence of abdominal contraction confirmed the diagnosis of detrusor hyperactivity (DH), if it was observed in the filling phase [13].
For the statistical analysis, the SPSS version 20.0 statistical package (Statistical Package for Social Studies, IBM®, Illinois) was used. For the descriptive analysis of the quantitative variables, means and standard deviation (SD) were used, while for the qualitative variables, frequencies and percentages were used. To evaluate the quantitative variables before and after treatment, the Student's t-test was used for paired samples. Statistical significance was established at the 95% level (p < 0.05).

Results
Thirty female patients with a diagnosis of SUI and 30 with UUI (n = 60) have been evaluated. UUI is more frequent in older patients (UUI 67.3 ± 10.19 years vs SUI 58.6 ± 8.54 years), and with a statistically significant difference (p = 0.0028) Table 1 and Fig. 1.
In the urodynamic analysis (free flowmetry), patients with UUI have smaller bladders than patients with SUI (voiding volume in UUI 275.8 ± 178.95 vs 411.03 ± 203.62 in SUI) and with statistically significant difference (p = 0.083). In the same test, the maximum flow (Qmax) is higher in patients with SUI compared with UUI (19.6 ± 7.07 vs 16.06 ± 8.54), although the difference only showed a trend towards significance (p = 0.0836). In filling cystomanometry (instrumented  (Table 1).
With regard to UUI, the proposed rehabilitation protocol (BFB plus TTNM) decreased DUF (from 7.2 ± 5.1 to 4.76 ± 3.14 episodes), NUF (from 2.51 ± 1.6 to 1.25 ± 1.18 episodes), increased the strength of the PFM measured by the maximum pressure (from 18.17 ± 12.09 to 21.07 ± 17.7 mmHg) and the mean pressure (from 3.42 ± 2.66 to 4 ± 3.46 mmHg) and significantly. The reduction in the use of absorbents/day, although it was reduced by half (from 1.37 ± 1.5 to 0.75 ± 1.16), was not significant ( Table 2).
Regarding the clinical-urodynamic correspondence according to the types of urinary incontinence, of 34 patients with clinical UUI, it was confirmed by urodynamics in 22 of them (64.7%), while of 40 patients with clinical SUI, urodynamic SUI was confirmed in 14 of them (35%) (Fig. 1). The UDS is more sensitive to diagnose UUI than to diagnose SUI, in this series of patients (64.7% UUI vs 35% SUI) (Fig. 2).

Discussion
To our knowledge, this is the first article that has attempted to identify age, clinical, manometric, and urodynamic differences between patients with UUI and SUI, contrast the clinical diagnosis with the urodynamic diagnosis, and propose the most appropriate personalized treatment according to the type of incontinence, according to the existing evidence to date, in the daily clinical practice of a third level (specialized) rehabilitation service.
In our study, we have found that UUI is more frequent in older people (67.3 years), while SUI occurs in slightly younger people (58.6 years) and the difference is significant (p = 0.0028). These findings correspond to the majority of researchers who argue that age is a risk factor for presenting UI [4]. Geanini-Yagüez and Fernández-Cuadros argue that SUI progresses with age, presenting a maximum peak between 40 and 60 years and later, there is a decrease in prevalence. On the contrary, UUI and MUI show a progressive increase with age [4]. This would explain why SUI in this study was more frequent at 58.6 years (age group 40-60 years), while UUI was more frequent at 67.3 years on average. These findings coincide with Weidner et al., who suggest that urinary urgency (UU) is more common in older women [18], and with Abrahams, who argues that UUI increases with age [19].
Urinary urgency is clinically characterized by the urge to urinate that is difficult to postpone, accompanied or not by urinary incontinence and is generally associated with an increase in DUF (> 8/day) and NUF (> 2/night). If these symptoms are reproduced during the filling phase in cystometry (urodynamic study), urodynamic UI or overactive bladder syndrome is diagnosed [20]. In our study, DUF and NUF were higher in patients with UUI compared with patients with SUI.  On the other hand, patients with SUI used more absorbents than patients with UUI. We have included the use of absorbents/day (pad test/24 h) as an outcome variable because some authors consider it an essential tool to assess the severity of incontinence (the more absorbents, the greater the severity) [21]. This would explain why in SUI, patients used more absorbents than in UUI. However, some organizations such as the NICE (National Institute for Health and Excellence) [22] do not consider the pad test (pad test/24 h) as a method of assessment in severity of incontinence; therefore, they do not indicate it as a diagnosis or as an outcome measure. This is basically because UI is defined as any loss capable of causing a social/hygiene problem, and not because it soaks pads or is objectified by their use [4].
This study has shown that there are urodynamic differences between the bladders of SUI vs UUI patients. A normal or continent bladder has normal urethral capacity and resistance. An urgent bladder or UUI has a small bladder capacity, and the bladder is overactive (OAB). The bladder in SUI has low urethral resistance. In the bladders with MUI, bladder capacity is reduced, the bladder is overactive, and the urethra has low resistance [2]. In this study we have shown that bladder capacity (valued by free flowmetry and cystomanometry) is lower in patients with UUI. The Qmax (maximum flow) is higher in SUI than in UUI (19.6 ± 7.07 vs 16.06 ± 8.54 ml/s), although this difference does not reach statistical significance. This would be explained because in SUI, the urethra has low resistance to the passage of urine, and because the flow of urine is proportional to the volume of urine evacuated (the higher the volume evacuated, the higher Qmax).
UDS is a simple procedure that allows to define behavior in certain patients with symptoms or alterations of LUT. The UDS is the standard test in the research and diagnosis of voiding dysfunction and its result is operator-dependent. It is essential to know the components of UDS (free flowmetry, filling cystomanometry, and pressure-flow study) and the interpretation of normal values in UDS [23].
Free flowmetry is a noninvasive study that gives an estimate of the voiding act but may be influenced by the effectiveness of detrusor contraction, sphincter relaxation, or urethral permeability. The evacuated voiding volume varies from 0 to 1000 ml; Qmax in people under 40 years is > 25 ml/s, while in over 40 s, it should be > 15 ml/s. Patients with SUI have high flows due to minimal output resistance from urethra [23]. This explains why in this study Qmax is higher in SUI than in the UUI. Dominguez-Arroyo maintains that the voiding volume is between 300 and 600 ml [24]. In our study, UUI patients were below that value (275.8 ml) while patients with SUI were within that range (411.03 ml). This is consistent with Salinas-Casado, who refers to patients with UUI presented higher urinary frequency and lower bladder capacity than patients with SUI (123 ml in UUI, 241 ml in SUI) [25]. Katz argues that UUI patients evacuate urine volumes lower than normal values [11]. In addition to Qmax being dependent on the evacuated volume, Qmax is lower in UUI [11]. In contrast, Katz also states that Qmax is higher in SUI because the resistance when urinating is lower [11]. In short, Qmax is higher in SUI by the highest volume urinated and by the lower resistance of urethra [11].
In the cystomanometric study, the maximum bladder capacity is defined as the volume in which the patient has the urgent desire to urinate and usually coincides with the strong urination desire in UDS [23]. This would explain why patients with UUI in this study presented a capacity of 266.3 ml while patients with SUI had a higher capacity (308.6 ml).
Finally, the pressure-flow Study is used to evaluate the emptying characteristics of the LUT and simultaneously monitor the detrusor pressure and the flowmetry (Qmax), for which the detrusor contractility and the outlet obstruction are basically evaluated [23]. The pressure-flow study diagnoses hypocontractility of the detrusor and/or bladder outlet obstruction, while flowmetry and cystomanometry diagnose detrusor hyperactivity, urgency, or stress urinary incontinence (after accommodation, cough or Valsalva) [23,24]. In this study, we have not found differences in Qmax in the pressure-flow study.
In rehabilitation, the management of UI includes conservative measures, such as bladder training, PFMT with/ without BFB, and TTNM. Clinical guidelines state that the initial treatment should always include PFMT/BFB, while TTNM should be reserved for patients with UUI [22]. However, we believe that PFMT, BFB, and TTNM can be used in both pathologies (SUI and UUI, even in MUI). Fernández-Cuadros has stated that BFB (instrumented PFMT technique) is effective in the management of UI (stress, urgency, and mixed UI) [1,12,26]. This is due to the fact that (1) PFMT/BFBs activate the perineum detrusor reflex (Mahoney's R3), acting on the UUI, (2) PFMT/BFBs maintain the correct position and mobility of the urethra, acting on SUI, (3) PFMT/BFBs compress the urethra against the pubic symphysis, increasing urethral pressure, giving resistance to voluntary urination, useful in SUI, and (4) PFMT/BFBs protect passive restraints and nerve structures from stretching [4].
The management of UUI and overactive bladder in the rehabilitation contemplates the use of TTNM [27][28][29]. The stimulation frequency of 2 to 10 Hz produces detrusor inhibition; therefore, it would be useful in the management of overactive bladder [30], while stimulation at 35-40 Hz favors reinnervation and the conversion of fast to slow twitch fibers (useful in SUI) [31]. However, stimulation at 20 Hz (frequency used in this study) could take advantage of both modes of action, and be prescribed in both SUI and UUI [31].
In this study, in patients with UUI, BFB plus TTNM significantly decreased DUF, NUF, use of absorbents/day (24-h pad test), and improved the strength of the PFM. These findings coincide with previous studies, where we have shown that PFMT/BFB improve UUI [1,4,12,32,33].
In the same way, in this study, we have shown that PFMT/ BFB in SUI patients, and TTNM in UUI has significantly decreased DUF, NUF, and the use of absorbents/day (24-h pad test) and have improved the strength of PFM in patients with SUI. These findings correspond to what has been previously published by our study group [1,4,12,32,33].
With regard to the clinical-urodynamic correlation, in this study, we have observed that clinical UUI has been confirmed by UDS in 64.7% of cases (22 of 34 cases), while clinical SUI has been confirmed by UDS in 35.1% of cases (14 of 40 cases). In this study, the UDS is more sensitive in diagnosing UUI than in detecting SUI (64.7% vs 35.1%).
Urodynamic SUI is confirmed if, in the filling phase of cystomanometry, there is a loss of urine when abdominal pressure increases (coughing with a full bladder) without observing any detrusor contraction (Fig. 3a). On the other hand, urodynamic urinary urgency is confirmed if involuntary detrusor contractions appear in the same phase associated with a sensation of urgency or during accommodation maneuvers (overactive bladder). If losses also appear during the emergency episode, the diagnosis of urodynamic UU with associated incontinence (urodynamic UUI) will be established [34] (Fig. 3b).
Despite the fact that the UDS provides valuable information on the functioning of the LUT to the point of being universally considered as the gold standard for the study of the symptoms of LUT, there is still controversy regarding its diagnostic utility [9,22].
In this sense, a diagnostic test such as UDS should be performed if and only if its result will affect the management or the results of the treatment and will lead the patient to an alternative treatment route [9]. Glazener et al. argue that urodynamic diagnosis can influence in the proposed medical treatment. Thus, in the face of LUT symptoms, if the UDS confirmed SUI, the suggested treatment would be surgical. On the contrary, if the diagnosis is detrusor hyperactivity, the treatment ceases to be surgical and becomes conservative (drugs, BFB, TTNM, botulinum toxin type A) [8].
However, there are authors who are in favor and others against the value of UDS in the diagnosis and management of UI. Among the arguments in favor, free flowmetry is able to rule out voiding dysfunction with a negative predictive value (NPV) of 97.3%. The existence of detrusor hyperactivity is considered a risk factor for success in surgery for SUI. The arguments against are that UDS is not capable of differentiating the different causes of SUI, for example, hypermobility of the urethra, or deficit of the internal sphincter. Furthermore, determining the severity of SUI based on values such as the LPP (leakage point pressure) do not modify the surgical result [9].
All diagnostic tests have advantages and disadvantages and this is not different to UDS. The disadvantages of UDS, according to Wyndaele, are that this test does not reproduce Fig. 3 a A urodynamic study of a patient with clinical SUI is observed, where stress urinary incontinence (see red arrow) is observed in the urination canal (after 3 regular coughing episodes). b A urodynamic study of a patient with clinical UUI is appreciated, where detrusor hyperactivity (green arrow) is observed in the detrusor P channel, in addition to urinary urgency with secondary incontinence (red arrow) in the urination channel (in maximum filling sensation). P ves, vesical pressure; P abd, abdominal pressure; P det, detrusor pressure; Bomba, pump; Tiempo, time; Acomodación, accommodation; Punto de fuga, leaking point; Comando de micción, micturition order the symptoms of LUT. Furthermore, it requires skill, knowledge, and experience, making it an operator-dependent test [35]. The UDS has a clinical-urodynamic correlation in SUI of 80%. The presence of detrusor hyperactivity in the asymptomatic population is 10-20% and the reproducibility of the test is 10%. Symptoms do not correlate too much in UDS, and sometimes, UDS shows values that do not correlate with the urological problem [35]. According to the same author, the advantage of UDS is that this test is the most specific to assess the function of the LUT. The UDS allows classifying the clinical diagnosis of SUI in 91%, in pure SUI (51%) and in SUI and detrusor hyperactivity (38%). Therefore, the UDS is very important if conservative treatment of UI has failed or if there are complex forms of UI clinically detected [35]. In our study, the clinical-urodynamic correlation in the diagnosis of SUI was lower (35.1%).
Finazzi-Agro maintains that there are 2 randomized clinical trials (RCTs) that suggest that UDS is unnecessary in patients with uncomplicated SUI and they are the VALUE and the VISUS study [7,36]. Organizations such as NICE have relied on these studies to advice against its use [22]. However, of the patients with SUI, only 36% are non-complex patients, while 64% present complex symptoms [36]. In this sense, UDS generates (a) valuable information, (b) confirms the diagnosis, (c) generates clinical decision-making, and (d) allows giving adequate advice to the patient. Definitely, Finazzi-Agro establishes that more clinical information will be of greater benefit to the patient [36]. Salinas-Casado refers that UDS offers prognostic reliability in the surgical treatment of SUI (suburethral sling), because if UUI coexists, the clinical results will be worse [25].
Giner-Santamaría has observed that UDS confirms SUI in 60% of cases, it is not reproducible in 20%, and MUI is seen in 10%. On the other hand, in patients with UUI, UDS confirmed the diagnosis in 64% (bladder hyperactivity, urgency, or UUI); it was not reproducible in 12% and showed uncoordinated urination in 8% [37]. This diagnostic assessment was similar to that observed in our study, to diagnose UUI (64.7%), but not to confirm SUI (35.1%). The explanation for this difference is that the UDS establish that up to 33% of clinical diagnoses are incorrect; 20% of SUI symptoms cannot be reproduced in UDS, and 10% of UDS are normal in patients with incontinence symptoms [11]. Van Leijsen maintains that even 25-30% of patients with SUI are normal in the UDS [7].
According to the previous considerations, we agree with Yamanishi et al., who maintain that UDS is indicated in the following: (a) failure of conservative treatment; (b) if invasive treatment is considered (TTNM, botulinum toxin in the detrusor); (c) bypass/reservoir surgery to protect the upper urinary tract; and (d) to perform training with BFB [38].
For the above reasons, we have taken into account both the clinical and urodynamic diagnosis to establish the correct treatment and propose the most appropriate treatment according to current clinical guidelines (PFMT/BFB for SUI; BFB plus TTNM for UUI). With this proposed treatment, we have been able to observe clinical and manometric improvement and decrease the use of absorbents, in patients treated in daily clinical practice in rehabilitation, in a third-level hospital.
A limitation of the study is the small sample size of the study (n = 60). However, the conclusions obtained have been shown to be significant despite the small sample size.
The strengths of the study have been several. The UDS was carried out according to ICS (International Continence Society) standards and by qualified personnel (Hospital Urology Department). The history, the physical examination, and the manometric evaluation have been carried out by the same rehabilitation physician (MEFC) in order to avoid inter-observer variability. Treatment protocols are based on current knowledge about the management of UI; therefore, this sample is a representation of the usual medical practice carried out in a rehabilitation service of the 3rd level of care in a Spanish Public Hospital. The sample is obtained from a real, non-experimental population. We hope that the findings observed in this study can be extrapolated to other services, given the observed effectiveness of the proposed treatments in the management of UI.

Conclusion
There are age, clinical, manometric, and urodynamic differences in patients with UUI when compared with patients with SUI. UUI occurs in older patients; they present a greater number of daytime and nocturnal urinary frequency episodes and use fewer absorbents than patients with SUI. Patients with UUI evacuate a smaller urine volume and have a lower maximum flow (in flowmetry) and a lower bladder capacity (in cystomanometry) than patients with SUI. The rehabilitation treatment proposed in daily clinical practice (PFMT/BFB with or without TTNM) improves SUI and UUI. In this study, the UDS has shown a greater clinicalurodynamic correlation in UUI than in SUI.