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Transobturator suburethral tape (TOT) procedures are becoming the first-line surgical method for urodynamic stress incontinence, with equivalent efficacy and similar modes of action compared with retropubic suburethral tape (RPT) procedures1–4.
Tape location and tape tension are among the most frequently investigated factors that might affect surgical outcome of suburethral tape procedures4–15. While some researchers have found that a tape located at the start of the distal third of the urethra is important for optimal outcome14, 15, others regard tape location as being less crucial4, 9, 10. In contrast, tape tension is universally accepted as a factor affecting surgical efficacy and postoperative complications related to suburethral tape procedures1, 4–6, 9, 12, 14, 15.
Ultrasound is a clinically feasible method that can offer morphological information and assess functional behavior of suburethral tapes4–8, 14. With three-dimensional (3D) or 4D technology, the location and course of suburethral tape can be defined9. Utilizing 4D ultrasound technology, we conducted this study firstly to explore the ultrasound changes in tape location and tape tension as a result of increased intra-abdominal pressure in women who had been successfully treated with TOT placement, and secondly to explore ultrasound differences in tape location and tape tension between women with and those without stress urinary incontinence (SUI) and those with and those without complications such as overactive bladder (OAB) symptoms and voiding difficulty, following TOT placement.
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Between January 2007 and January 2010, women who had undergone a Monarc subfascial hammock procedure (American Medical Systems, Minnetonka, MN, USA) in the treatment of urodynamic stress incontinence were enrolled prospectively into the study. After excluding women with a history of diabetes, neurological disease or stroke, previous or concomitant pelvic reconstructive surgery, concurrent symptoms of urgency or urgency incontinence, ≥ Stage II pelvic floor relaxation assessed by the Pelvic Organ Prolapse Quantification (POP-Q) system16 or detrusor overactivity demonstrated on urodynamic studies, 56 women were left for analysis. Approval to carry out this study was obtained from the Institutional Review Board Committees in Cathay General Hospital (CT9650 and CT9897). Informed consent was provided by all participants. Methods, definitions and units conform to the standards recommended by the International Continence Society16, except where specifically noted.
The Monarc subfascial hammock procedures were performed by a single investigator (W.C.H.). With the woman under general anesthesia, a 1-cm midline incision in the anterior vaginal wall was made approximately 1 cm proximal to the external urethral meatus. The tape was placed using the ‘outside-in’ route as recommended by the manufacturer. The tape tension was adjusted by placing Metzenbaum scissors between the tape and the urethra during plastic sheath removal in all women.
Postoperative assessments were scheduled at 3 months, 12 months and 24 months following the procedure. At each follow-up, women were assessed by a question-directed interview, SUI severity was assessed by the Sandvik Incontinence Severity Index17 and Ingelman-Sundberg Scale18, impact on quality of life was assessed by Taiwanese versions of the short forms of Urogenital Distress Inventory (UDI-6) and Incontinence Impact Questionnaire (IIQ-7)19, pelvic examination, cough stress test and 4D ultrasound.
The interview addressed the storage and voiding functions of the lower urinary tract and encompassed urinary frequency, nocturia, SUI, urgency, urgency incontinence and voiding difficulty. The question concerning SUI was: ‘Following the procedure, have you ever leaked urine while laughing, coughing, sneezing, during physical exercise, or while bending over, moving or heavy lifting?’ The question concerning urgency was: ‘Following the procedure, have you ever perceived a sudden, compelling desire to pass urine which is difficult to defer?’ The question concerning urgency incontinence was: ‘Following the procedure, have you ever experienced involuntary loss of urine associated with urgency?’ The question concerning voiding difficulty was: ‘Following the procedure, have you ever had a slower urinary stream compared to previous performances or in comparison with others, or have you had the need to make an intensive effort to initiate, maintain, or improve urinary stream?’ If a woman answered ‘Yes’ to any question, for each symptom severity was further ranked by asking her how bothered she was by the symptom on a 4-point Likert scale, ranging from 0 (not bothered at all) to 1 (mildly bothered), 2 (moderately bothered) and 3 (severely bothered). Symptoms of OAB were defined as affirmative response to urgency with or without urgency incontinence.
Pelvic examination was performed with the woman lying in the dorsal lithotomy position and focused on healing status and pelvic support, with the latter being assessed using the POP-Q system. A cough stress test was performed with the patient standing, while ensuring by ultrasound that the bladder volume was approximately 200–300 mL. A positive cough stress test was defined as any visible leakage of urine on six consecutive vigorous coughs.
The 4D ultrasound assessments were conducted by a single investigator (W.C.H.) using an introital approach, when the woman was at rest, during maximum straining and during strong coughing. The ultrasound system was a Philips® iU22 (Philips Medical Systems, Bothell, WA, USA) equipped with a 3–9-MHz endovaginal volume transducer with an 85° acquisition angle at 2–3 Hz20. When the woman was lying in the lithotomy position with a full bladder (not standardized but with an estimated bladder volume of 200–300 mL), the endovaginal transducer was covered with a condom and placed at the introitus. It was adjusted to obtain a sagittal image covering the area including the symphysis pubis, urethra, bladder and anorectal junction, with the symphysis pubis located to the right and the external urethral meatus to the inferior. First, using 3D ultrasound with automatic acquisition, images with the patient at rest were selected when the symphysis pubis, urethra, bladder neck and tapes were clearly visible. 4D ultrasound was then performed twice, during which patients were instructed orally, first to perform at least three maximum straining maneuvers and then to perform at least three strong coughs. All 3D and 4D volume datasets obtained at rest, during straining and during coughing were stored digitally for subsequent analysis.
Offline post-processing of the 3D and 4D ultrasound volume datasets was conducted by one investigator (J.M.Y.), blinded to the subjects' clinical information, using QLAB software, release 6.0, (Philips Medical Systems). For analysis of the impact of straining and that of coughing, we selected the image from each 4D dataset that demonstrated the most caudodorsal movement of the bladder neck in the sagittal plane. The selected resting, straining and coughing images were manipulated by rotating the z-axis in Plane 1 until the urethral segment anterior to the center of the suburethral tape was perpendicular to an imaginary horizontal line passing through the center of the suburethral tape (Figure 1a)20. The selected resting, straining and coughing images were manipulated sequentially, by rotating the x-axis in Plane 3 until the two arms of the tape were clearly and symmetrically visible (Figure 1b). The sagittal view in which the urethra lay perpendicular to the imaginary horizontal line and the axial view in which both arms of the tape were clearly demonstrated at the level of the imaginary horizontal line were selected for analysis. For each parameter, three measurements were made and their average was used for statistical analysis.
Figure 1. Ultrasound images showing planes used for quantitative measurements in the assessment of location and tension of transobturator suburethral tape (T, arrows): sagittal image (a) with the urethra (U) lying perpendicular to an imaginary horizontal line passing through the center of the tape (dashed line) and (b) the corresponding axial image at the level of the imaginary horizontal line. B, bladder; SP, symphysis pubis.
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Ultrasound parameters representing tape location
Tape location was evaluated by measuring the sagittal tape–symphysis pubis distance (sTSD), sagittal tape–symphysis pubis angle (sTSA) and tape percentile (Figure 2) in the manipulated resting, straining and coughing images. sTSD was defined as the distance between the center of the tape and the inferior border of the symphy- sis pubis in the sagittal plane. sTSA was defined as the angle between a line from the center of the tape to the inferior border of the symphysis pubis and the midline of the symphysis pubis in the sagittal plane. Tape position along the urethra was measured and expressed as a percentage of the urethral length, referred to as ‘tape percentile’, as follows: proximal urethral length (distance from bladder neck to mid-point of tape) divided by total urethral length (distance from bladder neck to external urethral meatus) in the sagittal plane, with the bladder neck and the external urethral meatus representing 0% and 100% of the urethral length (i.e. 0th and 100th percentile), respectively5. Intra- and interobserver reliabilities of measurement of sTSD and sTSA were good to very good at rest, on straining and during coughing in 20 volume datasets tested by intraclass correlation (Table 1).
Figure 2. Ultrasound parameters for assessing location of transobturator suburethral tape (T): sagittal tape–symphysis pubis distance (sTSD, dashed, double-headed arrow), sagittal tape–symphysis pubis angle (sTSA) and tape percentile. The tape percentile is calculated as a percentage of proximal urethral length (PUL) by total urethral length (TUL) (solid, double-headed arrows). B, bladder; SP, symphysis pubis; U, urethra.
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Table 1. Intra- and interobserver reliability of ultrasound measurements of sagittal tape–symphysis pubis distance (sTSD) and sagittal tape–symphysis pubis angle (sTSA) (n = 20) in women with transobturator suburethral tape
| ||ICC (95% CI)|
|Resting|| || |
| sTSD||0.840 (0.639–0.933)||0.794 (0.551–0.913)|
| sTSA||0.799 (0.559–0.915)||0.831 (0.622–0.930)|
|Straining|| || |
| sTSD||0.795 (0.552–0.913)||0.851 (0.661–0.938)|
| sTSA||0.747 (0.465–0.892)||0.857 (0.674–0.941)|
|Coughing|| || |
| sTSD||0.769 (0.504–0.902)||0.807 (0.576–0.919)|
| sTSA||0.852 (0.664–0.939)||0.805 (0.571–0.918)|
Ultrasound parameters representing tape tension
Tape tension was evaluated by observing urethral encroachment and measuring sagittal tape–urethra distances at the upper end of the tape (sTUDu), at the central point of the tape (sTUDc) and at the lower end of the tape (sTUDl) (Figure 3a) and axial urethral central echolucent area at the central point of the tape (aUCEAc) (Figure 3b) in the manipulated resting, straining and coughing images. Urethral encroachment was defined as the presence, in the sagittal plane, of an indentation in the urethral outer wall beside the tape, with a plateau-like elevation of the inner wall and narrowing of the echolucent urethral core, which encompassed the lumen and surrounding tissues5. sTUDu, sTUDc and sTUDl were defined as the shortest distance between the upper, center and lower ends, respectively, of the tape and the midline of the urethral echolucent area in the sagittal plane. aUCEAc was measured as the size of the urethral central echolucent area in the axial plane. We have demonstrated previously that the reliability of measurement of sTUDu, sTUDc, sTUDl and aUCEAc is good to very good at rest, on straining and during coughing20.
Figure 3. Ultrasound parameters for assessing tension of transobturator suburethral tape (T): (a) tape–urethral distances at upper end (sTUDu), central point (sTUDc) and lower end (sTUDl) of the tape (sagittal plane) and (b) urethral central echolucent area at the tape center (aUCEAc, circle) (axial plane). B, bladder; SP, symphysis pubis; U, urethra.
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Continuous and categorical data are presented as mean ± SD or n (%), respectively. The postoperative ultrasound changes between rest and maximum straining as well as between rest and the strongest cough were assessed by Wilcoxon signed ranks test. The clinical and ultrasound differences between women with and without postoperative SUI, OAB symptoms and voiding difficulty were evaluated by Mann–Whitney U-test, Yates corrected chi-square test or Fisher's exact test as appropriate. All analyses were carried out using SPSS for Windows, release 17.0 (SPSS Inc., Chicago, IL, USA) and the level of significance was 5%. However, for Bonferroni correction of multiple comparisons, P < 0.002 was considered significant.
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The mean ± SD age of the 56 women in the study was 53.5 ± 11.5 years, the median parity was 3 and the mean ± SD body mass index was 24.7 ± 3.2 kg/m2. There were 27 (48.2%) postmenopausal women and three (5.4%) women had undergone a Cesarean section. At the 3-month follow-up, all 56 women had a negative cough stress test, whereas only 47 (83.9%) women were free from the symptoms of SUI. Moreover, nine (16.1%) women reported OAB symptoms and 12 (21.4%) reported de novo or worsening voiding difficulty.
On ultrasound, distinct straining and coughing images for quantitative analysis were only available in 45 (80.4%) and 48 (85.7%) datasets, respectively. In women in whom the tape procedure had been successful, compared with during resting, sTSA was significantly increased on straining (P < 0.0001) and the rate of urethral encroachment was significantly increased on straining (P = 0.001) and during coughing (P < 0.0001). sTUDu was significantly reduced during coughing (P = 0.007) and sTUDc, sTUDl and aUCEAc were significantly reduced on straining (P = 0.005, P = 0.003 and P < 0.0001, respectively) and during coughing (P < 0.0001, P = 0.001 and P = 0.005, respectively). After Bonferroni adjustment, only the increases in sTSA on straining and rates of urethral encroachment on straining and during coughing, as well as the decreases in sTUDc and sTUDl during coughing and aUCEAc on straining, remained significant.
Compared with women without SUI symptoms following the Monarc procedure, women who reported postoperative symptoms of SUI had lower tape percentile at rest (P = 0.017) and on straining (P = 0.001). Women with postoperative SUI symptoms did not manifest urethral encroachment under any circumstances, while some women without symptoms did, leading to a significant difference between the groups on straining (P = 0.003) and during coughing (P = 0.003) (Table 2). Women with postoperative OAB symptoms had shorter resting sTSD (P = 0.038) and larger sTSA (P = 0.022) than did those without OAB symptoms (Table 3). Compared with those who did not, women who reported de novo or worsening voiding difficulty postoperatively had larger resting sTSA (P = 0.022) and higher incidence of urethral encroachment at rest (P = 0.008) (Table 4).
Table 2. Differences between ultrasound measurements in women with and those without stress urinary incontinence (SUI) 3 months after transobturator suburethral tape placement
|Variable||Without SUI||With SUI||P|
|Resting|| || || |
| n||47||9|| |
| sTSD (cm)||1.88 ± 0.41||2.01 ± 0.39||0.083|
| sTSA (°)||150 ± 14||140 ± 26||0.172|
| Tape percentile (%)||62 ± 8||47 ± 2||0.017|
| Encroachment||14 (30)||0 (0)||0.093|
| sTUDu (cm)||0.72 ± 0.21||0.78 ± 0.22||0.390|
| sTUDc (cm)||0.64 ± 0.18||0.66 ± 0.18||0.554|
| sTUDl (cm)||0.69 ± 0.16||0.69 ± 0.19||0.964|
| aUCEAc (cm2)||0.37 ± 0.24||0.38 ± 0.34||0.770|
|Straining|| || || |
| n||38||7|| |
| sTSD (cm)||1.82 ± 0.48||1.99 ± 0.38||0.039|
| sTSA (°)||166 ± 20||150 ± 15||0.511|
| Tape percentile (%)||63 ± 9||40 ± 11||0.001|
| Encroachment||24 (63)||0 (0)||0.003|
| sTUDu (cm)||0.67 ± 0.13||0.75 ± 0.22||0.259|
| sTUDc (cm)||0.54 ± 0.13||0.57 ± 0.17||0.635|
| sTUDl (cm)||0.58 ± 0.14||0.60 ± 0.17||0.771|
| aUCEAc (cm2)||0.27 ± 0.23||0.39 ± 0.46||1.000|
|Coughing|| || || |
| n||44||4|| |
| sTSD (cm)||1.83 ± 0.44||2.00 ± 0.41||0.385|
| sTSA (°)||155 ± 17||141 ± 15||0.582|
| Tape percentile (%)||58 ± 11||45 ± 18||0.021|
| Encroachment||36 (82)||0 (0)||0.003|
| sTUDu (cm)||0.73 ± 0.23||0.74 ± 0.13||0.957|
| sTUDc (cm)||0.58 ± 0.17||0.59 ± 0.19||0.986|
| sTUDl (cm)||0.63 ± 0.17||0.63 ± 0.15||0.871|
| aUCEAc (cm2)||0.29 ± 0.22||0.45 ± 0.63||0.957|
Table 3. Differences between ultrasound measurements in women with and those without de novo overactive bladder (OAB) symptoms 3 months after transobturator suburethral tape placement
|Variable||Without OAB||With OAB||P|
|Resting|| || || |
| n||47||9|| |
| sTSD (cm)||1.96 ± 0.41||1.70 ± 0.28||0.038|
| sTSA (°)||151 ± 21||156 ± 13||0.022|
| Tape percentile (%)||61 ± 8||64 ± 10||0.151|
| Encroachment||10 (21)||4 (44)||0.206|
| sTUDu (cm)||0.79 ± 0.22||0.66 ± 0.19||0.230|
| sTUDc (cm)||0.67 ± 0.18||0.56 ± 0.09||0.098|
| sTUDl (cm)||0.71 ± 0.19||0.58 ± 0.09||0.073|
| aUCEAc (cm2)||0.40 ± 0.26||0.21 ± 0.12||0.059|
|Straining|| || || |
| n||38||7|| |
| sTSD (cm)||1.91 ± 0.45||1.66 ± 0.36||0.196|
| sTSA (°)||165 ± 18||169 ± 12||0.474|
| Tape percentile (%)||60 ± 10||65 ± 6||0.296|
| Encroachment||19 (50)||5 (71)||0.422|
| sTUDu (cm)||0.75 ± 0.20||0.60 ± 0.24||0.207|
| sTUDc (cm)||0.58 ± 0.17||0.49 ± 0.12||0.264|
| sTUDl (cm)||0.61 ± 0.17||0.50 ± 0.08||0.264|
| aUCEAc (cm2)||0.30 ± 0.28||0.16 ± 0.13||0.245|
|Coughing|| || || |
| n||40||8|| |
| sTSD (cm)||1.92 ± 0.44||1.68 ± 0.22||0.240|
| sTSA (°)||153 ± 17.4||165 ± 18||0.207|
| Tape percentile (%)||56 ± 12||56 ± 8||0.986|
| Encroachment||29 (73)||7 (88)||0.659|
| sTUDu (cm)||0.74 ± 0.22||0.60 ± 0.24||0.395|
| sTUDc (cm)||0.59 ± 0.18||0.52 ± 0.10||0.375|
| sTUDl (cm)||0.63 ± 0.17||0.53 ± 0.11||0.235|
| aUCEAc (cm2)||0.31 ± 0.28||0.22 ± 0.16||0.528|
Table 4. Differences between ultrasound measurements in women with and those without de novo or worsening voiding difficulty 3 months after transobturator suburethral tape placement
|Variable||Without voiding difficulty||With voiding difficulty||P|
|Resting|| || || |
| n||44||12|| |
| sTSD (cm)||1.93 ± 0.40||1.87 ± 0.44||0.768|
| sTSA (°)||150 ± 21||159 ± 13||0.022|
| Tape percentile (%)||61 ± 8||63 ± 8||0.343|
| Encroachment||7 (16)||7 (58)||0.008|
| sTUDu (cm)||0.76 ± 0.22||0.76 ± 0.21||0.802|
| sTUDc (cm)||0.66 ± 0.18||0.64 ± 0.18||0.716|
| sTUDl (cm)||0.70 ± 0.18||0.68 ± 0.19||0.742|
| aUCEAc (cm2)||0.38 ± 0.25||0.36 ± 0.27||0.524|
|Straining|| || || |
| n||36||9|| |
| sTSD (cm)||1.91 ± 0.47||1.76 ± 0.28||0.545|
| sTSA (°)||166 ± 17||159 ± 19||0.297|
| Tape percentile (%)||60 ± 9||58 ± 15||0.966|
| Encroachment||19 (53)||5 (56)||0.983|
| sTUDu (cm)||0.71 ± 0.23||0.71 ± 0.14||0.103|
| sTUDc (cm)||0.56 ± 0.18||0.58 ± 0.12||0.713|
| sTUDl (cm)||0.58 ± 0.17||0.64 ± 0.14||0.339|
| aUCEAc (cm2)||0.24 ± 0.18||0.38 ± 0.40||0.748|
|Coughing|| || || |
| n||36||12|| |
| sTSD (cm)||1.95 ± 0.44||1.80 ± 0.42||0.719|
| sTSA (°)||152 ± 16||157 ± 19||0.457|
| Tape percentile (%)||56 ± 11||58 ± 14||0.444|
| Encroachment||27 (75)||9 (75)||1.000|
| sTUDu (cm)||0.76 ± 0.23||0.71 ± 0.22||0.431|
| sTUDc (cm)||0.60 ± 0.18||0.57 ± 0.17||0.336|
| sTUDl (cm)||0.65 ± 0.16||0.62 ± 0.16||0.662|
| aUCEAc (cm2)||0.38 ± 0.41||0.27 ± 0.16||0.913|
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We found that success of surgical placement of TOT in the treatment of urodynamic stress incontinence appears to require an appropriate tape location, in the region of the middle to lower-middle of the urethra, and proper mechanical interactions during stress. A distally placed tape along with excessive tension on the urethra was the morphologic feature in our study associated with OAB symptoms and/or voiding difficulty after the procedure.
There are limited studies exploring quantitatively the correlation of surgical outcome with the location and tension of suburethral tapes. In this study we used the sTSD, sTSA and tape percentile to represent tape location, with the first two of these parameters expressed in the polar coordinate system, indicating the tape position relative to the symphysis pubis21, and the tape percentile indicating the tape location relative to the urethra. Our results suggest that a larger sTSA and higher tape percentile would indicate a more caudal tape location. We also described the development of urethral encroachment and quantified tape tension through different urethral sections by measuring sTUDu, sTUDc, sTUDl and aUCEAc. A higher incidence of urethral encroachment, shorter sTUDu, sTUDc, sTUDl and smaller aUCEAc would suggest more tape tension on the urethra.
Our study demonstrated the importance of tape location in achieving urinary continence following TOT procedures. When women in whom the procedure had been successful strained, the tape position became more caudal relative to the symphysis pubis, while still remaining at the middle to lower-middle of the urethra. This suggested that the tape moved in accordance with urethral motion during increased intra-abdominal pressure. Our findings support those of other reports: that a proximally located tape is associated with persistent SUI symptoms22 and that an optimal tape location of 40th to 70th percentile leads to greater surgical success6, 14. Midurethral positioning is regarded as being important in achieving urinary continence as it allows the tape to act as a fulcrum to produce dynamic kinking of the urethra14, 22 or as a mechanical device to enhance the increase of intraurethral pressure5, 6 with stress. A proximally located tape cannot act as a fulcrum22 or fails to provide adequate mechanical interaction with the urethra5, 6 during increased intra-abdominal pressure. Dietz et al., in contrast, found that the subjective cure rate after RPT procedures was not affected by tape location10; this may have been due to higher tape tension nullifying the importance of tape location. It has been reported that TOTs have more proximal resting and straining locations and remain further from the symphysis pubis on straining, compared with RPTs1.
This study also demonstrated the importance of tape tension in achieving urinary continence following TOT procedures. When women in whom the procedure had been successful strained or coughed, greater tape tension was produced, as suggested by the findings of increased urethral encroachment rates and decreased sTUDu, sTUDc, sTUDl and aUCEAc. Women with postoperative SUI failed to develop urethral encroachment during increased intra-abdominal pressure. These findings suggest that mechanical compression of the urethra between the tape and the symphysis pubis is likely to be one of the curative effects offered by the TOT approach. Our findings are compatible with those of Kociszewski et al.14, who reported that the best outcome was found in cases whose ultrasound findings demonstrated tension of the elastic tape on the urethra during straining. A tape position too far away from the urethra has been reported to be associated with a higher failure rate7, 14. In the literature dynamic urethral kinking has been recognized as a sign of tape tension, with reported incidences of around 90%23 following RPT and 24–50% following TOT procedures5, 13, 23. Our unexpected findings, showing insignificant differences in sTUDu, sTUDc, sTUDl and aUCEAc between successful and failed cases, may be due to the small number of failed cases in our study.
The effect of suburethral tape on OAB symptoms is not completely understood. This study demonstrated that women with postoperative OAB symptoms had a more caudoventral resting tape position relative to the symphysis pubis compared with women without OAB symptoms. Previous studies have demonstrated a tighter tape tension exerted on the mid-urethra as being the causative factor of de novo urgency following TOT procedures22. Additionally, OAB symptoms were seen only in patients with a shorter distance between the tape and the urethral lumen7. We therefore speculated that a distally placed tape along with some tension on the urethra, but not sufficient to cause the development of urethral encroachment during resting, may be factors associated with postoperative OAB symptoms.
Tape tension exerted on the mid-urethra is regarded as accounting for de novo voiding symptoms including acute and chronic retention22. Voiding dysfunction is more likely to occur if the tape is too tight or too close to the urethra6, 7, 14, 24. Consistent with our previous study6, this study demonstrated that significantly more women with postoperative voiding difficulty developed urethral encroachment at rest, a sign of undue tape tension5, 6. This study also demonstrated a more caudoventral resting tape position in women reporting de novo or worsening voiding difficulty after Monarc procedures. Our findings showing the association of OAB symptoms and voiding difficulty with a more caudal resting tape position imply the possibility of a causative role of anterior vaginal wall relaxation in postoperative voiding difficulty25.
This study may have been limited by the subjective definitions of surgical outcome that we used. The subjective outcome measurements provided information regarding the experience of the women over a longer period compared with more objective tests such as stress test, pad test or urodynamic studies, which merely reflect a measurement at one point in time26. Additionally, patient satisfaction should be reassessed at frequent intervals27. We feel that this therefore justifies our use of subjective outcome measures. The relatively high voiding difficulty rate that we observed may be attributed to the fact that we classified women strictly as having postoperative voiding difficulty if they gave a positive response to any symptom in the category of voiding difficulty. Furthermore, this study may have inherent limitations as it was small-sized and short-term. Finally, in view of the multiple comparisons, some of the significant results may be spurious. Yet, despite these limitations, our study clearly demonstrated the significance of tape location and tape tension on surgical outcome in TOT procedures.
The surgical outcome of TOT placement depends on a complex interaction between the tape and the urethra. Both tape location and tape tension may affect this interaction and surgical outcome. 4D ultrasound provides a novel means with which to assess the location and tension of TOTs.