International Urogynecology Journal

, Volume 24, Issue 3, pp 407–411

Predictor of de novo stress urinary incontinence following TVM procedure: a further analysis of preoperative voiding function

Authors

  • Masato Kuribayashi
    • Department of Integrative Cancer Therapy and UrologyKanazawa University, Graduate School of Medical Science
    • Department of Integrative Cancer Therapy and UrologyKanazawa University, Graduate School of Medical Science
  • Kazutaka Narimoto
    • Department of Integrative Cancer Therapy and UrologyKanazawa University, Graduate School of Medical Science
  • Satoko Urata
    • Department of Integrative Cancer Therapy and UrologyKanazawa University, Graduate School of Medical Science
  • Shohei Kawaguchi
    • Department of Integrative Cancer Therapy and UrologyKanazawa University, Graduate School of Medical Science
  • Mikio Namiki
    • Department of Integrative Cancer Therapy and UrologyKanazawa University, Graduate School of Medical Science
Original Article

DOI: 10.1007/s00192-012-1882-0

Cite this article as:
Kuribayashi, M., Kitagawa, Y., Narimoto, K. et al. Int Urogynecol J (2013) 24: 407. doi:10.1007/s00192-012-1882-0

Abstract

Introduction and hypothesis

The purpose of this study was to evaluate the predictors of de novo stress urinary incontinence (SUI) in patients undergoing a tension-free vaginal mesh procedure (TVM) for pelvic organ prolapse (POP).

Methods

Sixty-five patients without SUI were assessed with regard to voiding function by a pressure flow study and clinical characteristics.

Results

The mean age of the patients was 67 ± 8.3. Of the 65 patients, 41 (63 %) maintained urinary continence postoperatively and 24 (37 %) showed de novo SUI. In univariate analysis, the de novo SUI group included a significantly higher proportion of patients with preoperative obstruction, defined as moderate or greater obstruction according to the Blaivas nomogram (29 vs 7 %, P = 0.035). In multivariate analysis, urethral obstruction was an independent predictor of de novo SUI with an odds ratio of 12.616 (95 % confidence interval 1.580–268.731).

Conclusions

Preoperative evaluation of urethral obstruction will contribute to prediction of de novo SUI combined with a conventional diagnosis of occult SUI.

Keywords

De novo SUIPelvic organ prolapsePressure flow studyTVM procedure

Introduction

Transvaginal mesh surgery for pelvic organ prolapse (POP) has been widely adopted because of its favorable treatment outcome and low rate of complications. Transvaginal polypropylene mesh repair kits have been applied clinically and have shown good efficacy compared with traditional anterior colporrhaphy [1]. The frequencies of peri- and postoperative complications are low, and critical events are rare [2]. With regard to treatment outcome, Vaiyapuri et al. reported both subjective and objective cure rates exceeding 90 % [3].

De novo stress urinary incontinence (SUI) is one complication following POP surgery in patients who had urinary continence before surgery [4, 5]. Because the aim of mesh surgery is to improve quality of life (QOL) as well as achieve morphological repair, the occurrence of postoperative SUI is disadvantageous from the viewpoint of QOL. Previous studies investigating the incidence of de novo SUI following the vaginal approach to POP repair without concomitant anti-incontinence procedures reported lower risks ranging from 2 to 22 % [69]. On the other hand, Al-Mandeel et al. recently reported that approximately one third of women treated with POP surgery only developed de novo SUI and that the risk of de novo SUI may be higher than previously thought [10].

In patients with POP, kinking or external compression of the urethra plays a role in continence [11, 12]. That is, de novo SUI is a result of the disappearance of such urethral obstructive conditions by anatomical reconstruction. As we previously reported, urethral obstruction shows a greater degree of reduction after transvaginal mesh surgery [13]. This suggests a possible relationship between urethral obstruction and the mechanism by which SUI is masked preoperatively. However, there have been no urodynamic studies of the relationship between de novo SUI and preoperative obstructive findings. Thus, the present study was performed to evaluate patients’ preoperative characteristics and urodynamic study parameters to investigate the relationship between preoperative obstructive findings and de novo SUI.

Materials and methods

Patients without preoperative SUI who underwent surgery with no concomitant anti-incontinence procedures were eligible for the present study. Patients were eligible if they showed negative stress test results. The stress test was performed in the lithotomy position with the urinary bladder filled with 250 ml saline without POP repositioning. Exclusion criteria were urinary tract infection, urge urinary incontinence requiring medication, and bladder capacity of less than 250 ml. Sixty-five patients were investigated prospectively for at least 6 months after the operation; 25 of the 65 patients had been included in our previous study [13]. The inclusion criterion was a cystocele defined as point Aa of −1 or more in the Pelvic Organ Prolapse Quantification (POP-Q) scoring system; therefore, all 65 patients underwent anterior repair during the operation. Preoperatively, they were assessed with regard to voiding function by urodynamic studies, including a pressure flow study and evaluation of age, body mass index (BMI), parity, history of hysterectomy, and POP-Q stage.

In the pressure flow study procedure, a 12-F double-lumen catheter was inserted into the urinary bladder transurethrally and equilibrated to the pressure of the empty urinary bladder. Intra-abdominal pressure was substituted for intrarectal pressure measured with a transrectally inserted 6-F balloon catheter. Intravesical pressure was recorded under conditions of sterile saline instillation at 50 ml/min. Detrusor pressure was calculated by subtracting intra-abdominal pressure from intravesical pressure. Examinations were performed with POP left as is during the pressure flow study. Obstruction was evaluated by the Blaivas nomogram [14]. The surgical procedure was based on that reported by the French TVM group with soft polypropylene mesh (Gynemesh PS™) [15]. The mesh was cut into a shape similar to that of Prolift™ as previously reported [16, 17]. Patients with cystoceles only underwent anterior TVM, and those requiring level 1 or 2 repair, such as those with uterine prolapse or vault prolapse, were treated by anterior and posterior TVM.

Patients underwent pelvic examination including a stress test at 1, 3, and 6 months and 1 and 2 years after the operation. De novo SUI was defined as a positive stress test with the urinary bladder filled with 250 ml of saline, as in the preoperative examination. All terminology conformed to International Continence Society (ICS) standards [18]. This study was approved by our Institutional Ethics Committee, and all participants provided written informed consent before inclusion in the study. Statistical assessments were performed using the paired t test, Wilcoxon’s signed rank test, and the chi-square test in univariate analysis and logistic regression in multivariate analysis with P < 0.05 taken to indicate statistical significance.

Results

The characteristics of the 65 patients are shown in Table 1. The mean age was 67 ± 8.3 years. Of the 65 patients, 57 were urinary continent preoperatively, and the remaining 8 had urge urinary incontinence without SUI. None of these eight required medication for urge urinary incontinence; patients requiring a pad for urge urinary incontinence were excluded from the investigation.
Table 1

Baseline characteristics of the patients (n = 65)

Baseline characteristic

Number

Age, mean ± SD (range)

67 ± 8.3 (44–86)

BMI, mean ± SD (range)

24.1 ± 3.4 (20.5–40.3)

Parity, median (range)

2 (1–4)

History of hysterectomy

 

 No

51

 Yes

14

POP-Q

 

Cystocele

 

  Grade 2

13

  Grade 3 or 4

52

Uterine/vault prolapse

 

  Stage I or II

42

  Stage III or IV

23

BMI body mass index

Of the 65 patients, 41 (63 %) maintained urinary continence postoperatively and 24 (37 %) showed de novo SUI with a median period of 6 months (range 1–12 months) after the operation. Of the 24 patients, 7 underwent a urethral sling operation for de novo SUI with a median interval of 8 months after the TVM procedure; 6 were prescribed 40 μg clenbuterol hydrochloride, which is used to treat SUI in Japan; and the remaining 11 were treated conservatively with diet and pelvic floor muscle training. Figure 1 shows the distribution of the maximum flow rate (MFR) and detrusor pressure at maximum flow in the preoperative pressure flow study on the Blaivas nomogram. No patients showed abnormalities on electromyography during the pressure flow study.
https://static-content.springer.com/image/art%3A10.1007%2Fs00192-012-1882-0/MediaObjects/192_2012_1882_Fig1_HTML.gif
Fig. 1

Comparison of maximum flow and detrusor pressure at maximum flow according to the Blaivas nomogram between urinary continence and de novo SUI groups

Univariate analysis results between the urinary continence and de novo SUI groups are shown in Table 2. There were no significant differences in age, BMI, parity, or history of hysterectomy between the two groups. There was also no significant difference in the proportion of patients with POP-Q grade 3 or higher cystoceles, whereas patients with stage III or higher uterine prolapse or vault prolapse tended to develop de novo SUI, although the difference was not significant. The presence of preoperative obstruction evaluated by the pressure flow study was significantly associated with de novo SUI. The de novo SUI group included a significantly higher proportion of patients with preoperative obstruction. Considering a moderate or more severe obstruction according to the Blaivas nomogram as obstructive, 3 of the 41 patients in the urinary continence group and 7 of the 24 patients in the de novo SUI group were considered to have obstruction (7 vs 29 %, respectively; P = 0.035). Sensitivity and positive predictive value for preoperative obstruction to detect de novo SUI were 29 % (7 of 24) and 70 % (7 of 10), respectively. The mean MFR investigated by standard uroflowmetry was 25.1 ± 12.6 and 24.2 ± 14.3 ml/s in the urinary continence group and de novo SUI group, respectively (P = 0.345). The mean MFR investigated during the pressure flow study was 13.2 ± 7.3 and 9.8 ± 6.5 ml/s, respectively. Although not statistically significant, MFR at pressure flow study in the urinary continence group tended to be higher than that in the de novo SUI group (P = 0.052).
Table 2

Comparison between continence and de novo SUI groups

  

Continence (n = 41)

De novo SUI (n = 24)

P value

Age, mean ± SD

 

66.9 ± 7.9

67.1 ± 9.1

0.493

BMI, mean ± SD

 

23.6 ± 1.9

25.0 ± 5.0

0.633

Parity

   

0.564

 ≤2

 

23

16

 

 ≥3

 

18

8

 

History of hysterectomy

   

0.405

 No

 

34

17

 

 Yes

 

7

7

 

POP-Q

    

 Cystocele

≤ grade 2

8

5

0.299

 

≥ grade 3

33

19

 Uterine prolapse

≤ stage II

29

12

0.094

 

≥ stage III

12

12

MFR at UFM (ml/s), mean ± SD

25.1 ± 12.6

24.2 ± 14.3

0.345

MFR at PFS (ml/s), mean ± SD

13.2 ± 7.3

9.8 ± 6.5

0.052

Obstructive grade according to the Blaivas nomogram

 Moderate or severe

 

3

7

0.035

 Mild or none

 

38

17

Surgical procedure

 Anterior only

 

6

2

0.456

 Anterior and posterior

 

35

22

SUI stress urinary incontinence, BMI body mass index, MFR maximum flow rate, UFM uroflowmetry, PFS pressure flow study

In multivariate analysis, grade 3 or higher cystoceles, stage III or higher uterine prolapse, MFR at uroflowmetry, and urethral obstruction defined as moderate or more were analyzed by logistic regression as shown in Table 3. Urethral obstruction was an independent predictor of de novo SUI with an odds ratio (OR) of 12.616 [95 % confidence interval (CI) 1.580–268.731], whereas the other variables were not statistically significant.
Table 3

Multivariate analysis of predictors of de novo SUI

 

P value

Odds ratio (95 % CI)

Cystocele ≥ grade 3

0.862

1.153 (0.244–6.742)

Uterine/vault prolapse ≥ stage III

0.267

2.108 (0.560–8.124)

MFR at UFM

0.975

1.048 (0.051–25.076)

Urethral obstruction moderate or more

0.033

12.616 (1.580–268.731)

SUI stress urinary incontinence, MFR maximum flow rate, UFM uroflowmetry, CI confidence interval

Discussion

Our study showed that moderate or more severe preoperative urethral obstruction according to the Blaivas nomogram was an independent predictor of de novo SUI, whereas examination findings of POP-Q stage III or more did not reach statistical significance. The results of the present study indicate that a pressure flow study is useful to evaluate urethral conditions that mask SUI preoperatively and support the mechanism of de novo SUI reported previously [11, 12]. There have been no previous studies regarding the efficacy of preoperative pressure flow studies to predict de novo SUI. We also emphasize that preoperative evaluation of urethral obstruction requires no artificial POP reduction. The efficacy of occult SUI in prediction of de novo SUI has been reported. Although there may not be a precise definition of occult SUI and de novo SUI, conventionally, the former seems to refer to SUI diagnosed by POP reduction preoperatively [19], whereas the latter indicates a postoperative condition. It is certain that there is a correlation between occult SUI and de novo SUI, and some authors reported the usefulness of preoperative assessment of occult SUI to predict de novo SUI [1921]. However, we were also concerned about the various methods used to diagnose occult SUI. While the diagnosis of occult SUI requires reduction of POP, many different methods of repositioning POP (e.g., the use of a pessary, Sims speculum, cotton swab, vaginal packing, and forceps ring) have been described [22]. Karateke et al. reported that the pessary test in preoperative assessment of patients with severe POP and concomitant anti-incontinence surgery contributed to both the objective and subjective cure rates postoperatively [21]. Although instruments that mainly sustain level 1 support, such as pessaries and forceps rings, have been used to avoid urethral obstruction during restoration of POP [21, 22], there is still some doubt about whether level 1 support represents the postoperative condition in patients with cystoceles only, especially in low-stage POP. In addition to the method of POP repositioning, bladder volume, patient position, and application of abdominal pressure (by the Valsalva maneuver or by coughing) have not been standardized. The significance of a diagnosis of occult SUI is still a matter of debate.

Two separate mechanisms, urethral hypermobility and intrinsic sphincter deficiency (ISD), have been suggested as causes of SUI [23, 24]. That is, de novo SUI is the result of manifestations of urethral hypermobility and/or ISD secondary to surgical procedures for POP. It is also worth noting that half of the patients with de novo SUI did not show urethral obstruction preoperatively (Table 2). This suggests that not all cases of de novo SUI are caused by release of urethral obstruction and that POP may mask urethral hypermobility and/or ISD in some patients without urethral obstruction. In the present study, the MFR in the pressure flow study tended to be higher in the urinary continence group compared with the de novo SUI group (13.2 ± 7.3 vs 9.8 ± 6.5 ml/s, respectively; P = 0.052), although the difference was not statistically significant. The reason for the discrepancy between the MFR in the pressure flow study and MFR in uroflowmetry is not clear. However, we supposed that the MFR in the pressure flow study was measured in a uniform manner compared with the MFR in uroflowmetry in terms of bladder capacity; the condition of POP and the patients’ position during voiding may have also contributed. Whether there is a relationship between a lower MFR and the possibility of masked urethral hypermobility remains to be investigated. De novo SUI should be discussed from several viewpoints, i.e., whether urethral hypermobility or ISD is mainly responsible for de novo SUI. However, it was not possible here to determine whether urethral hypermobility or ISD was mainly masked by preoperative urethral obstruction because problems of diagnosing occult SUI also arise secondary to the necessity of restoring POP to diagnose urethral hypermobility and ISD preoperatively. Standardization of the POP restoration method may be needed to clarify the accurate mechanism of de novo SUI.

Whether concomitant anti-incontinence procedures during POP surgery are justified also remains unclear [25]. Difficulties in predicting de novo SUI have made this a challenging issue. An important reason for predicting de novo SUI is to determine whether concomitant anti-incontinence procedures should be performed during POP repair surgery. Few prospective randomized trials have been performed regarding concomitant anti-incontinence procedures. Brubaker et al. reported that Burch colposuspension significantly reduced postoperative symptoms of stress incontinence without increasing other lower urinary tract symptoms [26]. Although this was a well-designed randomized controlled trial, the surgical procedure used for POP was abdominal sacrocolpopexy, which is a surgical treatment not for cystoceles, but for vault prolapse. In addition, the anti-incontinence procedure was not a midurethral sling, which is a common procedure for prevention of de novo SUI performed concomitantly with mesh repair for POP. The concomitant midurethral sling has been applied in some patients undergoing mesh surgery, such as the TVM procedure, with favorable outcomes [2, 3]. However, the treatment criteria for a concomitant midurethral sling were not definite. Excessive anti-incontinence procedures should be avoided as long as their necessity and justifiability remain controversial. Predictors of de novo SUI also contribute to the decision regarding whether a concomitant anti-incontinence procedure should be performed.

The present study had some limitations. First, the results should be interpreted with caution because of the small sample size of 65 patients and follow-up period of only 6 months. Further investigations will improve the reliability of the results. Second, the lower sensitivity and positive predictive value of the preoperative obstructive findings are insufficient to predict de novo SUI without utilizing other diagnostic methods. Sensitivity and positive predictive value leave something to be desired by considering the cutoff value for obstruction/non-obstruction. Standardization of diagnosing occult SUI will contribute to more precise prediction of de novo SUI combined with preoperative obstructive findings.

In conclusion, preoperative obstruction as evaluated by pressure flow studies can be used as an independent predictor of de novo SUI. Combined with the conventional diagnosis of occult SUI, we can predict de novo SUI following POP surgery more accurately, which might help to determine whether concomitant anti-incontinence surgery is required.

Conflicts of interest

None.

Copyright information

© The International Urogynecological Association 2012