Objective
We sought to correlate signs and symptoms of pelvic organ prolapse (POP) with pubovisceral muscle avulsions on magnetic resonance imaging (MRI).
Study Design
In this retrospective cohort study of 189 women with recurrent POP or unexplained symptoms of pelvic floor dysfunction, we reviewed T2-weighted pelvic floor MRI and categorized defects as minor or major avulsion, or as no defect present. Outcomes were correlated to quality-of-life questionnaire scores and data on obstetric and surgical history, together with POP-Quantification (POP-Q) measurements. Multivariable ordinal logistic regression analysis with manual backward elimination was applied to calculate odds ratios (ORs).
Results
Major pubovisceral avulsions were diagnosed in 83 (44%) women, minor avulsions in 49 (26%) women, while no defects were seen in 57 (30%) women. Women with a history of episiotomy or anterior vaginal wall reconstructive surgery had a higher OR for more severe pubovisceral muscle avulsions (adjusted OR, 3.77 and 3.29, respectively), as did women with symptoms of POP (OR, 1.01, per unit increase) or higher stage POP of the central vaginal compartment based on POP-Q measurement “C” (OR, 1.18). Women with symptoms of obstructive defecation were more likely to have no defect of the pubovisceral muscle on MRI (OR, 0.97, per unit increase).
Conclusion
The variables episiotomy, previous anterior vaginal wall reconstructive surgery, POP-Q measurement “C,” and symptoms scored with the Urogenital Distress Inventory “genital prolapse” and Defecatory Distress Inventory “obstructive defecation” subscales are correlated with pubovisceral muscle avulsions on pelvic floor MRI.
Traditionally, diagnoses and treatment plans are based on a thorough medical history and physical examination, but imaging of the area of interest is becoming increasingly important. For conditions assembled under the term “pelvic floor dysfunction,” including pelvic organ prolapse (POP), imaging is not part of standard clinical practice, even though one of the risk factors for POP, ie, a traumatic avulsion of the pubovisceral muscle from the pubis, can be readily visualized. Pubovisceral muscle avulsions are thought to be mainly the result of a vaginal delivery and occur on a daily basis when, during second stage of labor, the pubovisceral muscle gets (partially) detached from its insertion to the pubis in up to 36% of women. Perineal ultrasonography and magnetic resonance (MR) imaging (MRI) can be used to visualize pubovisceral muscle avulsions, both with their specific advances and drawbacks regarding costs, availability, and spatial resolution. The Translabial 3D-Ultrasonography for Diagnosing Levatordefects (TRUDIL) study is currently performed in The Netherlands to evaluate which of these techniques is superior.
Pubovisceral muscle avulsions are observed as a partial detachment of the muscle from the pubis with loss of muscle bulk (minor pubovisceral avulsion) ( Figure 1 ) or as a complete loss of connection to the pubis or significant bilateral damage (major pubovisceral avulsion) ( Figure 2 ). Major pubovisceral avulsions have been reported to be associated with an increased risk of POP and recurrence of POP after surgery. Management of POP in women with recurrent POP or in whom there is a discrepancy between clinical signs and symptoms of pelvic floor dysfunction remains the most challenging in clinical practice and further exploration of the role of pubovisceral muscle avulsions in this group seems therefore particularly important. The aim of this study was to identify variables that predict the presence and severity of pubovisceral muscle avulsions. Outcomes of disease-specific quality-of-life questionnaires and POP-Quantification (POP-Q) measurements together with data on obstetric and surgical history were correlated to pubovisceral muscle avulsions on pelvic floor MRI.
Materials and Methods
The present retrospective cohort study was conducted among patients who visited the Department of Obstetrics and Gynaecology of the Radboud University Medical Centre in the period 2005 through 2011. Patients were referred for pelvic floor MRI as part of routine clinical workup in case of recurrent POP or when there was a discrepancy between clinical signs and symptoms of pelvic floor dysfunction. All women who underwent MRI and completed the disease-specific quality-of-life questionnaires were included. As pubovisceral muscle avulsions are thought to be mainly the result of a vaginal delivery, women who were not vaginally parous were not included in this study. Furthermore, women who had undergone pelvic floor reconstructive surgery in the period between MRI and completion of the questionnaires were excluded. Additional exclusion criteria were insufficient diagnostic quality of the MRI and (known) congenital defects of the female reproductive system. MRI was performed to determine degree of prolapse or to ascertain the possible cause(s) of symptoms. All data sets were retrospectively analyzed for pubovisceral muscle avulsions. The study was officially deemed exempt from institutional review board approval since all data were obtained as part of routine clinical workup.
The following validated questionnaires were used: Urogenital Distress Inventory (UDI), Incontinence Impact Questionnaire (IIQ), and Defecatory Distress Inventory (DDI). The UDI consists of 11 items on bothersome urinary symptoms, eg, urge and stress urinary incontinence, while the IIQ is composed of 13 items measuring the impact of urinary incontinence on quality of life. The DDI measures bothersome defecatory symptoms, eg, fecal incontinence (FI) and obstructive defecation, and consists of 10 items. Each item score ranges from 0-100, where 0 indicates the best quality of life and 100 indicates that all symptoms are present and are causing maximal bother. In all 3 questionnaires, the items are grouped over 5 subscales. Each subscale score is calculated by taking the mean of the corresponding item scores.
The anatomic degree of POP was measured using a simplified version of the International Continence Society POP-Q system. Hereby, the descent of the anterior, central, and posterior vaginal compartments was measured (point Ba, C, and Bp, respectively). These measurements are expressed in centimeters in relation to the hymenal remnants. A minus sign indicates that the maximal protrusion is above these remnants whereas points distal to the hymenal remnants have a positive outcome. Furthermore, the genital hiatus was measured. All measurements were performed during maximum Valsalva.
MRI data sets were analyzed to determine the presence and severity of pubovisceral muscle avulsions. A T2-weighted 3-dimensional (3D) turbo spin echo (1 × 1 × 1 mm 3 resolution) sequence and a higher in plane resolution axial T2-weighted turbo spin echo (0.5 × 0.5 × 3 mm 3 resolution) sequence were used to acquire MRI. Slice thickness was 3 mm without image spacing. The patient was in supine position, and imaging was performed after voiding. For bowel preparation, 10 mg of bisacodyl was taken the day before imaging and patients were asked to retain from ingesting fluids and solid foods up to 1 and 4 hours before the examination, respectively. Directly prior to imaging, 1 mL of scopolaminebutyl was injected intramuscularly to reduce intestinal mobility, thereby enhancing image quality. As the entire pelvic floor MRI protocol also includes a dynamic phase, the rectum was opacified using 120 mL of ultrasound gel. For the grading of pubovisceral muscle avulsions, only the static images were used. Images were imported and analyzed in a 3D imaging postprocessing program (TeraRecon Inc, San Mateo, CA). Hereby, the observers were able to reconstruct the 3D data sets to acquire images in the plane of minimal hiatal dimensions. The plane of minimal hiatal dimensions is defined as the angled axial plane with anteriorly the inferior aspect of the pubis and posteriorly the inner aspect of the pubovisceral muscle at the anorectal angle. This plane is thought to represent the true levator hiatus.
The MRIs were independently evaluated for pubovisceral muscle avulsions by an experienced radiologist (J.J.F., 4 years’ experience) and a novice observer (K.L., 6 months’ experience). Both participated in an online, case-based training presided over by the originator of the MRI levator defect scoring system (J.O.L. DeLancey, Ann Arbor, MI). Observers were trained to identify the relevant anatomy and landmarks of the female pelvis and to determine the presence and severity of pubovisceral muscle avulsions. This technique is known for its high interobserver reliability with a reported weighted Cohen kappa of 0.86 (95% confidence interval, 0.83–0.89). In scoring pubovisceral muscle avulsions on MRI, the arcuate pubic ligament is used as reference point. In the angled axial orientation, the slices 2-10 above this reference point are assessed. Avulsions observed on the axial images had to be confirmed in the coronal orientation. Both muscle sides were scored separately. The final score ranged from 0 (no defect) to 3 (complete loss of connection to the pubis), with a score of 1 indicating the loss of <50% of muscle bulk and score 2 representing ≥50% loss, both still with identifiable connection of the muscle to the pubis. A total score for the 2 sides (0-6) was then assigned and categorized as no defect (total score, 0), minor pubovisceral avulsion (total score, 1-3), or major pubovisceral avulsion (total score, 4-6 or unilateral score of 3). When scores of the 2 observers differed, MRIs were reviewed jointly to reach consensus. Both observers were blinded to all clinical findings.
Statistical methods
Analysis of variance was used to compare continuous variables among the 3 groups. In case of a statistically significant difference, the post hoc least significant difference procedure was applied for intergroup comparison. Fisher exact test was used to identify differences between groups in case of binary variables. Univariable ordinal logistic regression analyses were conducted with details on obstetric and surgical history, POP-Q data, and each questionnaire subscale score as independent variables, respectively. Pubovisceral muscle avulsion grading based on MRI was hereby used as dependent variable.
Multivariable ordinal logistic regression analysis with manual backward elimination was applied to identify potential predictors for pubovisceral muscle avulsions and to calculate odds ratios (ORs). By using ordinal logistic regression instead of multinomial logistic regression, the valuable information on ordering of the severity of pubovisceral muscle avulsions was retained. All variables with a P value < .20 on univariable ordinal logistic regression analyses were entered in the multivariable ordinal regression analysis. All analyses were performed using statistical software (SPSS 18.0 for Windows; SPSS Inc, Chicago, IL). P values < .05 were considered statistically significant.
Results
From 2005 through 2011, a total of 333 gynecological patients underwent pelvic floor MRI in our center. We were unable to analyze the MRI datasets of 6 patients due to imaging artifacts, eg, due to movement of the patient or presence of hip metal. Six women were excluded because of congenital anomalies affecting the pelvic floor, 5 additional women were nulliparous, and scheduled imaging in 1 woman was cancelled as a result of high body mass index. Of 315 women, 189 (60%) returned the questionnaires and were included in this study. Major and minor pubovisceral avulsions were diagnosed in 83 (44%) and 49 (26%) women, respectively, while 57 (30%) women had not sustained any visible trauma to the pubovisceral muscle. Of the women with an avulsion, 96 (73%) had bilateral trauma.
Table 1 outlines several patient characteristics including POP-Q measurements and details on obstetric and surgical history. Most differences observed were between the groups no defect and major pubovisceral avulsion and between the groups minor and major pubovisceral avulsion. In Table 2 , the subscale scores of the 3 questionnaires are depicted. A wide range was observed on all subscale scores. Women with pubovisceral avulsions, both minor and major, scored lower on 4 of 5 DDI subscales, eg, on the “pain” subscale, while women with major pubovisceral avulsions had a statistically significantly higher score on the UDI “genital prolapse” subscale.
| Variable | No defect (n = 57) | Minor avulsion (n = 49) | Major avulsion (n = 83) | P value | |||
|---|---|---|---|---|---|---|---|
| n | Median [range] or n (%) | n | Median [range] or n (%) | n | Median [range] or n (%) | ||
| Age, y | 57 | 55 [26–75] | 49 | 59 [31–83] | 83 | 55 [29–71] | .15 |
| BMI, a kg/m 2 | 54 | 27 [19–37] | 42 | 25 [19–34] | 80 | 25 [18–37] | .15 |
| Obstetric history | |||||||
| Parity, a no. | 57 | 3 [1–6] | 49 | 3 [1–6] | 83 | 2 [1–5] | .05 b , c |
| Age at first delivery, a y | 56 | 25 [17–39] | 47 | 25 [18–36] | 80 | 26 [17–37] | .09 b |
| Forceps delivery | 54 | 1 (2) | 43 | 2 (5) | 79 | 5 (6) | .58 |
| Vacuum delivery | 54 | 6 (11) | 43 | 2 (5) | 78 | 7 (9) | .51 |
| Cesarean delivery | 55 | 4 (7) | 44 | 2 (5) | 82 | 10 (12) | .33 |
| Episiotomy a | 53 | 28 (53) | 46 | 28 (61) | 75 | 63 (84) | < .001 b , c |
| Perineal laceration a | 49 | 20 (41) | 45 | 27 (60) | 71 | 39 (55) | .15 |
| Surgical history | |||||||
| Hysterectomy | 57 | 32 (56) | 49 | 34 (69) | 83 | 55 (66) | .34 |
| UI surgery | 57 | 18 (32) | 49 | 14 (29) | 83 | 31 (37) | .56 |
| Pelvic floor reconstructive surgery a | 57 | 31 (54) | 49 | 35 (71) | 83 | 73 (88) | < .001 b , c |
| No. of pelvic floor reconstructive surgeries | |||||||
| 1 a | 57 | 17 (30) | 49 | 18 (37) | 83 | 34 (41) | .43 |
| 2 | 57 | 11 (19) | 49 | 11 (22) | 83 | 21 (25) | .74 |
| ≥3 a | 57 | 3 (5) | 49 | 5 (10) | 83 | 17 (21) | .03 b |
| Vaginal compartment d | |||||||
| Anterior a | 56 | 20 (36) | 49 | 26 (53) | 80 | 62 (78) | < .001 b , c |
| Central a | 57 | 14 (25) | 48 | 17 (35) | 80 | 33 (41) | .12 b |
| Posterior a | 56 | 22 (39) | 48 | 23 (48) | 80 | 52 (65) | < .01 b |
| POP-Q measurements, cm | |||||||
| Ba a | 48 | −2 [−3 to 2] | 42 | −1 [−3 to 4] | 76 | −1 [−3 to 7] | .02 b , e |
| C a | 46 | −7 [−10 to 0] | 42 | −6 [−9 to 5] | 76 | −5 [−9 to 7] | .001 b , e |
| Bp | 47 | 0 [−3 to 2] | 42 | 0 [−3 to 6] | 76 | 0 [−3 to 7] | .29 |
| GH a | 46 | 3.5 [1–7] | 41 | 4 [3–7] | 74 | 4 [2–7] | < .01 b , e |
a Variable entered in multivariable analysis;
b Statistically significant difference between no defect and major avulsion;
c Statistically significant difference between minor and major defect;
d In 6 cases POP surgery had been performed, but it was not possible to determine the compartment involved;
e Statistically significant difference between no defect and minor avulsion.
| Questionnaires | No defect (n = 57) | Minor pubovisceral avulsion (n = 49) | Major pubovisceral avulsion (n = 83) | P value | |||
|---|---|---|---|---|---|---|---|
| n | Median (range) | n | Median (range) | n | Median (range) | ||
| UDI | |||||||
| Overactive bladder | 55 | 33.3 (0–100) | 45 | 22.2 (0–100) | 78 | 33.3 (0–88.9) | .35 |
| Urinary incontinence a | 55 | 33.3 (0–100) | 47 | 16.7 (0–100) | 79 | 33.3 (0–100) | .25 |
| Obstructive micturition | 56 | 25.0 (0–100) | 48 | 25.0 (0–100) | 80 | 16.7 (0–100) | .49 |
| Discomfort/pain | 55 | 33.3 (0–100) | 48 | 33.3 (0–100) | 83 | 33.3 (0–100) | .32 |
| Genital prolapse a | 55 | 16.7 (0–100) | 47 | 33.3 (0–100) | 82 | 33.3 (0–100) | .001 b |
| DDI | |||||||
| Constipation a | 56 | 33.3 (0–100) | 48 | 0 (0–100) | 83 | 16.7 (0–100) | .02 b , c |
| Obstructive defecation a | 55 | 33.3 (0–100) | 48 | 16.7 (0–83.3) | 83 | 16.7 (0–75) | < .001 b , c |
| Pain a | 56 | 33.3 (0–100) | 48 | 0 (0–100) | 83 | 0 (0–100) | < .01 b , c |
| Fecal incontinence a | 55 | 16.7 (0–100) | 49 | 16.7 (0–100) | 82 | 0 (0–100) | .27 |
| Flatus incontinence | 55 | 33.3 (0–100) | 49 | 33.3 (0–100) | 83 | 33.3 (0–100) | .66 |
| IIQ | |||||||
| Physical functioning | 55 | 33.3 (0–100) | 47 | 33.3 (0–83.3) | 78 | 33.3 (0–100) | .37 |
| Mobility | 54 | 33.3 (0–100) | 48 | 44.4 (0–100) | 81 | 33.3 (0–100) | .67 |
| Social functioning | 53 | 22.2 (0–88.9) | 44 | 16.7 (0–100) | 79 | 22.2 (0–100) | .84 |
| Embarrassment | 52 | 25.0 (0–100) | 46 | 16.7 (0–100) | 78 | 16.7 (0–100) | .44 |
| Emotional health | 57 | 55.6 (0–100) | 48 | 33.3 (0–100) | 80 | 33.3 (0–100) | .13 c |
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