Incidence and Risk Factors of Postoperative De Novo Voiding Dysfunction following Midurethral Sling Procedures

untitledIncidence and Risk Factors of Postoperative De Novo Voiding Dysfunction following Midurethral Sling Procedures
Hoon Ah Jang, Jae Hyun Bae, Jeong Gu Lee From the Department of Urology, College of Medicine, Korea University, Seoul, Korea
Purpose: To compare the incidence of postoperative de novo voiding dysfunction and to identify the risk factors affecting the development of de novo voiding dysfunction after various midurethral sling (MUS) procedures for female stress urinary incontinence (SUI). Materials and Methods: Women with SUI underwent MUS by various procedures [tension-free vaginal tape (TVT), tension-free vaginal tape obturator (TVTO), tension-free obturator tape (TOT), or TVT-secure]. Cases were reviewed retrospectively with follow-up of at least 6 months. The subjects were divided into 2 groups according to the presence of postoperative de novo voiding dysfunction. De novo voiding dysfunction was defined as a low maximal uroflow rate (Qmax15 ml/s) or a large post-voided residual urine volume (PVR100 ml) observed at 6 months postoperatively. Clinical and urodynamic parameters were compared between the voiding dysfunction (Group I) and normal voiding (Group II) groups according to MUS procedure. Results: Of the 625 subjects, 163 (26%) patients showed evidence of de novo voiding dysfunction (Group I). Of these 163 subjects, 12 (7.3%) patients complained of voiding symptoms. There was no difference in the incidence of de novo voiding dysfunction according to MUS procedure. Multivariate analysis showed Qmax to be the only independent risk factor for de novo voiding dysfunction. Conclusions: This study confirmed the considerable incidence of post- operative de novo voiding dysfunction, which is, however, mostly asym- ptomatic. As preoperative Qmax decreased, the chance of postoperative de novo voiding dysfunction increased. Identification of risk factors of voiding dysfunction in women undergoing MUS may help in planning for better follow-up and early detection of possibly inherent late com- plications of voiding dysfunction. (Korean J Urol 2009;50:762-766) Key Words: Urinary bladder, Complications
Korean Journal of Urology Vol. 50 No. 8: 762-766, August 2009
DOI: 10.4111/kju.2009.50.8.762
Correspondence to: Jeong Gu Lee Department of Urology, Korea University Anam Hospital, 126-1, 5-ga, Anam-dong, Sungbuk-gu, Seoul 136-705, Korea TEL: 02-920-5683 FAX: 02-928-7864 E-mail: [email protected]
The Korean Urological Association, 2009
INTRODUCTION
standard minimally invasive procedures used to treat stress
urinary incontinence (SUI) since tension-free vaginal tape (TVT)
was first described in 1996 by Ulmsten.1-4 Shortly thereafter,
a different method of tape insertion was described, in which
the tape passes through the obturator foramen (transobturator
tape, or TOT). Several variations of this method have been
introduced to reduce complications such as bladder perfora-
tion.5
In MUS, the sling provides dynamic kinking of the urethra
when abdominal pressures increase but not at the resting phase.
Thus, theoretically, MUS does not cause voiding dysfunction
such as weak stream, urinary hesitancy, and straining voiding
in itself. However, voiding dysfunction such as a decreased
maximal uroflow rate (Qmax) or increased post-voided residual
urine volume (PVR) has been reported after the MUS opera-
tion.3,6
Hoon Ah Jang, et alIncidence and Risk Factors of Postop. Voiding Dysfunction following MUS 763
Although a standard definition of female voiding dysfunction
is controversial,7 Qmax, PVR, and voiding time are used as
criteria for voiding dysfunction.3,8,9
The incidence of voiding dysfunction after MUS has been
reported to be between 4% and 55% and it may affect the
patient’s well-being and quality of life (QoL), consequently
decreasing patient satisfaction with the procedure.2,3,10
Postoperative voiding dysfunction can be self-limiting if
urinary symptoms do not exist and the PVR is adequate.1,11
However, in some severe cases, unavoidable removal or
relaxation of the mesh has been reported.12,13 The incidence and
risk factors of de novo voiding dysfunction after the MUS
procedure in patients with normal voiding function preopera-
tively have yet to be evaluated. The aim of the present study
was therefore to evaluate the incidence and risk factors of de
novo voiding dysfunction after the MUS procedure and to
compare these according to type of MUS device.
MATERIALS AND METHODS
Between 2004 and 2008, the medical records of patients who
underwent MUS for treatment of SUI utilizing various
procedures (TVT, TVTO, TOT, and TVT-secure) with at
least 6 months of follow-up were reviewed retrospectively.
To exclude preoperative voiding difficulties overlapping the
criteria of de novo voiding dysfunction, patients with pre-
operative Qmax less than 15 ml/s or PVR100 ml were
excluded. Patients who showed an obstructive pattern on
preoperative uroflowmetry or who had postoperative retention
were also excluded from the study.
Voiding dysfunction after MUS was defined when more than
one of the following was observed: 1) de novo postoperative
voiding symptoms (such as frequency, weak stream, voiding
difficulty, and residual sensation), 2) obstructive pattern on
uroflowmetry, 3) postoperative Qmax15 ml/s, 4) residual
urine volume100 ml. The study population was divided into
2 groups, one with postoperative de novo voiding dysfunction
(group 1) and the other with normal voiding after MUS (group
2). The criterion of Qmax15 ml/s as a cutoff value for
voiding dysfunction was based on the female voiding dys-
function guideline published by the Korean Continence So-
ciety.14
(LUTS) questionnaire (BF-LUTS), and urodynamic studies
including Qmax, PVR, and detrusor pressure at the maximum
flow rate (Pdetmax). Preoperative SUI symptoms were classi-
fied by Stamey grade.15
Postoperative evaluation was done at 3 and 6 months after
the MUS procedure. All patients were followed up with voiding
symptom history, physical examination, uroflowmetry, voiding
diary, and a validated questionnaire to assess the patient’s
perception of the results of and satisfaction with the surgery.
Cure of SUI was defined as complete dry and improvement as
still urine leakage but no treatment required or patient satisfied
with the results of the operation. Cure and improvement were
regarded as successful treatment of SUI.
Independent-sample t-tests and Pearson's chi-square test were
used to test the statistical significance of differences between
patients with and without postoperative voiding dysfunction.
Logistic regression analysis was used to explore the risk factors
of postoperative Qmax decrease. Statistical significance was
considered at p0.05.
A total of 631 patients underwent the MUS procedure during
this period. Among them, 4 patients with a preoperative Qmax
15 ml/s and 2 patients with postoperative urinary retention
were excluded. The analysis was therefore based on 625
patients.
with urethral catheterization. The urethral catheter was removed
after confirmation of no urine leakage on a cystogram after 1
week.
The mean age of the study population was 51.6 (range,
31-96) years and parity was 2.5 (range, 0-9). The mean duration
of follow-up was 7.4±3.6 (range, 6-9) months. Of the 625
patients, 204 had grade I, 405 had grade II, and 16 had grade
III SUI.
(VLPP) was 62.7±29.1 cmH2O. Postoperatively, 474 (76.1%)
patients were cured and 133 (21.2%) were improved. There
were no statistically significant differences in surgical outcomes
according to symptom grade (Stamey grade), cystocele, VLPP,
previous pelvic operation, concomitant vaginal operations, or
764 Korean Journal of Urology vol. 50, 762-766, August 2009
Table 1. Comparisons of demographic data between the postoperative voiding dysfunction group (Group 1) and the normal voiding group
(Group 2)
No. of patients 625 163 462
Age (years) 51.6±9.4 51.2±9.3 53.1±9.9 0.124 a
Body mass index 25.1±3.2 25.1±3.2 25.2±3.4 0.810a
Diabetes mellitus () 34 (5.4%) 8 (7.5%) 26 (5.0%) 0.829b
Parity (number of birth) 2.5±1.6 2.5±1.1 2.6±1.2 0.639b
Stamey sx grade (I/II/III) 204/405/16 38/64/5 166/341/11 0.843b
Cystocele (I/II/III/IV) 207/79/19/5 36/22/5/2 171/57/14/3 0.721b
Rectocele 37 9 28 0.562b
Surgical methods
TVT: tension-free vaginal tape, TVTO: tension-free vaginal tape obturator, TOT: tension-free obturator tape, Qmax: maximal uroflow rate,
Delta Qmax: postoperative Qmax-preoperative Qmax, a: independent-sample t-test, b: Pearson's chi-square test, c: paired t-test
different kinds of tape devices.
Postoperative voiding dysfunction was observed in 156
patients, in whom only 12 patients presented with obvious
voiding symptoms. Of the 12 patients with voiding symptoms,
3 complained of weak stream, 2 of residual urinary sensations,
and 7 of frequency. Of these 12, 5 patients has a Qmax15
ml/s or PVR100 ml. All 3 with weak stream had a Qmax
15 ml/s with PVR100 ml. Two patients with residual
urinary sensation had a Qmax15 ml/s. Among the 18 patients
with PVR100 ml, 7 patients had PVR200 ml, requiring
intermittent catheterization. One of them presented with a large
amount (308 ml) of PVR and was treated with postvoid
catheterization without symptom improvement; therefore, the
tape was released at 5 months after the MUS procedure.
Meanwhile, 132 patients in whom postoperative Qmax
decreased to 15 ml/s showed no voiding symptoms, and
among these, only 9 patients presented with residual urine
volume over 100 ml.
between the normal voiding group (group 2) and the voiding
dysfunction group (group 1) postoperatively, preoperative
Qmax was significantly lower in group 1 than in group 2 (p=
0.294; 21.3±11.7 ml/s in group 1 and 25.2±10.2 ml/s in group
2, respectively) (Table 1). The other variables such as surgical
methods, age, BMI, parity, DM, cystocele, and urodynamic
variables did not differ significantly between groups. The mean
change in Qmax (postoperative Qmax-preoperative Qmax) was
significantly greater in group 1 than in group 2.
To explore the risk factors for postoperative de novo voiding
dysfunction, multiple logistic regression was performed and
preoperative Qmax was found to be the only risk factor. As
the preoperative Qmax increased by 1 ml/s, the risk of
postoperative voiding dysfunction decreased by a factor of 0.95
(Table 2). The other variables such as age, BMI, and parity did
not show statistical differences in the multiple regression
analysis.
DISCUSSION
MUS is the single most common surgical modality for the
treatment of SUI, with good results and few complications. In
MUS, the sling provides dynamic kinking of the urethra when
abdominal pressures increase, while maintaining stability at the
resting phase, consequently preventing urinary incontinence. 16
Hoon Ah Jang, et alIncidence and Risk Factors of Postop. Voiding Dysfunction following MUS 765
Table 2. Analysis of risk factors for postoperative voiding dys-
function after midurethral sling
Age 1.012 50.90-52.37 0.518
Height 1.107 15.21-16.06 0.582
Weight 0.901 60.90-62.11 0.700
Parity 0.987 2.33-2.50 0.831
Diabetes mellitus 0.908 0.601
Cystocele
1
2
3
4
0.776
1.454
0.862
1.103
0.814
1.459
0.834
0.993
rate, a: logistic regression analysis
Thus, theoretically, MUS doesn’t cause voiding dysfunction
including weak stream, urinary hesitancy, or straining voiding.
Clinical risk may not be significant in the case of decreased
Qmax after MUS if the patient does not have voiding symp-
toms and has an acceptable PVR. However, considering the
possible long-term consequences on the bladder and upper
urinary tract, even if patients do not present voiding symptoms,
a decrease in Qmax should be carefully monitored. The
incidence of voiding dysfunction after the MUS procedure has
been reported to be from 4% to 55%.2,3,10 Also, changes in the
postoperative emptying phase, such as a decrease of Qmax,
obstructive pattern on uroflowmetry, and increase of PVR have
been reported.7,17,18 It is commonly agreed that MUS com-
presses the midurethra, thus affecting voiding during the
emptying phase.
Our study showed the cure and improvement rate of SUI to
be 76.1% and 21.4%, respectively, which is similar to the
results of other studies.19,20 In our study, postoperative evalua-
tion was performed at least 6 months after the MUS procedure.
Qmax was significantly decreased postoperatively, but the
voided volume and PVR showed no significant changes.
Boustead and Singh6 reported a decrease in Qmax from 30-35
ml/s to 20-25 ml/s after the TVT procedure. Sander et al18 also
reported decreased Qmax, increased PVR, and obstructive
pattern of uroflow after TVT. But less than half of those
patients showed symptoms of voiding dysfunction postopera-
tively. In our study, a low Qmax preoperatively was shown as
a risk factor of de novo postoperative voiding dysfunction,
whereas the individual decreased range of Qmax after the MUS
procedure was greater in the de novo voiding dysfunction group
than in the normal voiding group. Saline et al3 reported that
20% of patients presented with decreased Qmax of less than
15 ml/s and risk factors for decreased Qmax were age and
preoperative low Qmax, which was comparable to our results.
Taken together, the above results indicate that a low preopera-
tive Qmax is a risk factor for postoperative presence of voiding
dysfunction. Decrease of Qmax postoperatively may also occur
in patients with low Pdetmax or bladder outlet obstruction.
However, in our study, there was no difference in the preopera-
tive Pdetmax between groups, suggesting that the postoperative
decrease of Qmax was not affected by preoperative low Pdet-
max or bladder outlet obstruction. On the other hand, Wang
et al17 defined voiding dysfunction as PVR above 100 ml and
low preoperative Qmax and reported that postoperative urinary
infection was one of the risk factors of postoperative voiding
dysfunction.
In our study, only a small portion of the patients with
objective de novo voiding dysfunction (Qmax15 ml/s or PVR
100 ml) were symptomatic. These findings indicated that the
significant changes in objective clinical parameters such as
Qmax or PVR did not overlap with the symptoms the patients
felt, indicating the necessity to identify patients with potential
postoperative voiding dysfunction by regular uroflowmetry and
PVR measurement, especially in high-risk groups.
According to other reports on the incidence of postoperative
de novo voiding dysfunction according to MUS procedure,
Daneshgari et al21 found no differences according to the method
of inserting the tape. Latthe et al22 also reported the same
conclusion, with findings similar to ours. The method used to
insert the tape did not seem to affect the development of
postoperative voiding dysfunction.
preoperative Qmax, the incidence of postoperative voiding
dysfunction became higher. In women with low preoperative
Qmax, a longer-term, regular follow-up should be recom-
mended to minimize the possible adverse consequences caused
766 Korean Journal of Urology vol. 50, 762-766, August 2009
by de novo voiding dysfunction.
CONCLUSIONS
In our study, a considerable rate of postoperative de novo
voiding dysfunction, although mostly asymptomatic, did exist.
Preoperative peak flow rate was regarded as the only risk factor
for postoperative de novo voiding dysfunction. There were no
differences in the incidence according to method of MUS. In
patients with low preoperative Qmax, the MUS procedure
should be performed carefully, considering the potential for
postoperative de novo voiding dysfunction.
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