Yvonne Hsu

Comparison of levator ani muscle defects and function in women with and without pelvic organ prolapse.

BACKGROUND: To compare levator ani defects and pelvic floor function among women with prolapse and controls. METHODS: Levator ani structure and function were measured in a case–control study with group matching for age, race, and hysterectomy status among 151 women with prolapse (cases) and 135 controls with normal support (controls) determined by pelvic organ prolapse quantification examination. Magnetic resonance imaging was used to determine whether there were “major” (more than half missing), “minor” (less than half of the muscle missing), or no defects in the levator ani muscles. Vaginal closure force at rest and during maximal pelvic muscle contraction was measured with an instrumented vaginal speculum. RESULTS: Cases were more likely to have major levator ani defects than controls (55% compared with 16%), with an adjusted odds ratio of 7.3 (95% confidence interval 3.9–13.6, P<.001) but equally likely to have minor defects (16% compared with 22%). Of women who reported delivery by forceps, 53% had major defects compared with 28% for the nonforceps women, adjusted odds ratio 3.4 (95% confidence interval 1.95–5.78). Women with prolapse generated less vaginal closure force during pelvic muscle contraction than controls (2.0 Newtons compared with 3.2 Newtons P<.001), whereas those with defects generated less force than women without defects (2.0 Newtons compared with 3.1 Newtons, P<.001). The genital hiatus was 50% longer in cases than controls (4.7±1.4 cm compared with 3.1±1.0 cm, P<.001). CONCLUSION: Women with prolapse more often have defects in the levator ani and generate less vaginal closure force during a maximal contraction than controls. LEVEL OF EVIDENCE: II

Interaction among apical support, levator ani impairment, and anterior vaginal wall prolapse.

OBJECTIVE: To use a biomechanical model to explore how impairment of the pubovisceral portion of the levator ani muscle, the apical vaginal suspension complex, or both might interact to affect anterior vaginal wall prolapse severity. METHODS: A biomechanical model of the anterior vaginal wall and its support system was developed and implemented. The anterior vaginal wall and its main muscular and connective tissue support elements, namely the levator plate, pubovisceral muscle, and cardinal and uterosacral ligaments were included, and their geometry was based on midsagittal plane magnetic resonance scans. Material properties were based on published data. The change in the sagittal profile of the anterior vaginal wall during a maximal Valsalva was then predicted for different combinations of pubovisceral muscle and connective tissue impairment. RESULTS: Under raised intra-abdominal pressure, the magnitude of anterior vaginal wall prolapse was shown to be a combined function of both pubovisceral muscle and uterosacral and cardinal ligament (“apical supports”) impairment. Once a certain degree of pubovisceral impairment was reached, the genital hiatus opened and a prolapse developed. The larger the pubovisceral impairment, the larger the anterior wall prolapse became. A 90% impairment of apical support led to an increase in anterior wall prolapse from 0.3 cm to 1.9 cm (a 530% increase) at 60% pubovisceral muscle impairment, and from 0.7 cm to 2.4 cm (a 240% increase) at 80% pubovisceral muscle impairment. CONCLUSION: These results suggest that a prolapse can develop as a result of impairment of the muscular and apical supports of the anterior vaginal wall. LEVEL OF EVIDENCE: II-2

Appearance of the Levator Ani Muscle Subdivisions in Magnetic Resonance Images

OBJECTIVE: Identify and describe the separate appearance of 5 levator ani muscle subdivisions seen in axial, coronal, and sagittal magnetic resonance imaging (MRI) scan planes. METHODS: Magnetic resonance scans of 80 nulliparous women with normal pelvic support were evaluated. Characteristic features of each Terminologia Anatomica–listed levator ani component were determined for each scan plane. Muscle component visibility was based on pre-established criteria in axial, coronal, and sagittal scan planes: 1) clear and consistently visible separation or 2) different origin or insertion. Visibility of each of the levator ani subdivisions in each scan plane was assessed in 25 nulliparous women. RESULTS: In the axial plane, the puborectal muscle can be seen lateral to the pubovisceral muscle and decussating dorsal to the rectum. The course of the puboperineal muscle near the perineal body is visualized in the axial plane. The coronal view is perpendicular to the fiber direction of the puborectal and pubovisceral muscles and shows them as “clusters” of muscle on either side of the vagina. The sagittal plane consistently demonstrates the puborectal muscle passing dorsal to the rectum to form a sling that can consistently be seen as a “bump.” This plane is also parallel to the pubovisceral muscle fiber direction and shows the puboperineal muscle. CONCLUSION: The subdivisions of the levator ani muscle are visible in MRI scans, each with distinct morphology and characteristic features. LEVEL OF EVIDENCE: III

The use of graft materials in vaginal pelvic floor surgery

To review recent literature on graft materials used in vaginal pelvic floor surgery.

Interrater reliability of assessing levator ani muscle defects with magnetic resonance images

The objective of this study is to determine interrater reliability of assessing pubovisceral levator ani muscle defects with magnetic resonance images. Normal pubovisceral muscle was assigned a grade of 0; PVM defects were graded as mild = 1 (less than half missing), moderate = 2 (more than half missing), and severe = 3 (total or near total loss). Among six pairs of examiners, percent agreement and weighted kappa coefficients were calculated to determine agreement between pairs of examiners and among all examiners (i.e., “overall”). For unilateral scoring, exact agreement was found in 83.7%, and differences of one, two, and three grades were found in 14.7, 1.5, and 0.1%, respectively. For bilateral scoring, exact agreement and differences of one, two and three grades were found in 75.4, 15.9, 6.9, and 1.6%, respectively. Thus, exact agreement or a one-point difference was reached in 91.3% of cases. When defect status was categorized as none/normal, minor, and major, the overall weighted kappa coefficient was 0.86 (95% CI 0.83, 0.89). There was variation among examiner pairs with unilateral (p = 0.002) and bilateral (p = 0.02) scoring, but not when defect status was categorized as none/normal, minor, and major (p = 0.59). There was agreement to within one point in 91% of cases when six examiner pairs scored levator ani defects on a seven-point scale. Examiner pairs discriminated injury similarly when defect status was categorized as normal/none, minor, or major.

Anterior vaginal wall length and degree of anterior compartment prolapse seen on dynamic MRI

The objective of the study was to determine the relationship between midsagittal vaginal wall geometric parameters and the degree of anterior vaginal prolapse. We have previously presented data indicating that about half of anterior wall descent can be explained by the degree of apical descent present (Summers et al., Am J Obstet Gynecol, 194:1438–1443, 2006). This led us to examine whether other midsagittal vaginal geometric parameters are associated with anterior wall descent. Magnetic resonance (MR) scans of 145 women from the prior study were suitable for analysis after eight were excluded because of inadequate visibility of the anterior vaginal wall. Subjects had been selected from a study of pelvic organ prolapse that included women with and without prolapse. All patients underwent supine dynamic MR scans in the midsagittal plane. Anterior vaginal wall length, location of distal vaginal wall point, and the area under the midsagittal profile of the anterior vaginal wall were measured during maximal Valsalva. A linear regression model was used to examine how much of the variance in cystocele size could be explained by these vaginal parameters. When both apical descent and vaginal length were considered in the linear regression model, 77% (R2 = 0.77, p < 0.001) of the variation in anterior wall descent was explained. Distal vaginal point and a measure anterior wall shape, the area under the profile of the anterior vaginal wall, added little to the model. Increasing vaginal length was positively correlated with greater degrees of anterior vaginal prolapse during maximal Valsalva (R2 = 0.30, p < 0.01) determining 30% of the variation in anterior wall decent. Greater degrees of anterior vaginal prolapse are associated with a longer vaginal wall. Linear regression modeling suggests that 77% of anterior wall descent can be explained by apical descent and midsagittal anterior vaginal wall length.

Posterior compartment anatomy as seen in magnetic resonance imaging and 3-dimensional reconstruction from asymptomatic nulliparas

OBJECTIVE The objective of the study was to identify characteristic anatomical features of the posterior compartment using magnetic resonance (MR) cross-sectional anatomy and 3-dimensional (3-D) modeling. STUDY DESIGN Supine, static proton-density MR images of 20 nulliparas were analyzed. MR images were used to create models in a selected exemplar. RESULTS The compartments upper, mid, and lower segments are best seen in the axial plane. It is bounded inferiorly by the perineal body, ventrally by the posterior vaginal wall, and dorsally by the levator ani muscles and coccyx. In the upper portion, the compartment is bordered laterally by the uterosacral ligaments, whereas in the middle portion, there is more direct contact with the lateral levator ani muscles. In the lower portion, the contact becomes obliterated because the vagina and levator ani muscles become fused to each another and to the perineal body. CONCLUSION The posterior compartment has characteristic anatomic features in MR cross-sectional anatomy that can be further elucidated and integrated with 3-D anatomy.

Measurement of the pubic portion of the levator ani muscle in women with unilateral defects in 3-D models from MR images

Develop a method to quantify the cross‐sectional area of the pubic portion of the levator ani muscle, validate the method in women with unilateral muscle defects, and report preliminary findings in those women.

Magnetic Resonance Imaging and 3-Dimensional Analysis of External Anal Sphincter Anatomy

OBJECTIVE: To use magnetic resonance images of living women and 3-dimesional modeling software to identify the component parts and characteristic features of the external anal sphincter (EAS) that have visible separation or varying origins and insertions. METHODS: Detailed structural analysis of anal sphincter anatomy was performed on 3 pelvic magnetic resonance imaging (MRI) data sets selected for image clarity from ongoing studies involving nulliparous women. The relationships of anal sphincter structures seen in axial, sagittal, and coronal planes were examined using the 3-D Slicer 2.1b1 software program. The following were requirements for sphincter elements to be considered separate: 1) a clear and consistently visible separation or 2) a different origin or insertion. The characteristic features identified in this way were then evaluated in images from an additional 50 nulliparas for the frequency of feature visibility. RESULTS: There were 3 components of the EAS that met criteria as being “separate” structures. The main body (EAS-M) is separated from the subcutaneous external anal sphincter (SQ-EAS) by a clear division that could be observed in all (100%) of the MRI scans reviewed. The wing-shaped end (EAS-W) has fibers that do not cross the midline ventrally, but have lateral origins near the ischiopubic ramus. This EAS-W component was visible in 76% of the nulliparas reviewed. CONCLUSION: Three distinct external anal sphincter components can be identified by MRI in the majority of nulliparous women.

Sexual activity and function in women more than 2 years after midurethral sling placement

OBJECTIVE The purpose of this study was to assess prospectively the effects of midurethral sling surgery on sexual function and activity. STUDY DESIGN Sexual activity and function was assessed in 597 women with stress urinary incontinence who were enrolled in a randomized equivalence trial of retropubic compared with transobturator midurethral slings. Repeated measures analysis of variance was used to assess changes in Pelvic Organ Prolapse/Urinary Incontinence Sexual Questionnaire scores over a 2-year period. RESULTS Significant, similar improvements in sexual function were seen in both midurethral sling groups. Mean Pelvic Organ Prolapse/Urinary Incontinence Sexual Questionnaire scores increased from 32.8 at baseline to 37.6 at 6 months and 37.3 at 24 months (P < .0001). Dyspareunia, incontinence during sex, and fear of incontinence during sex each significantly improved after surgery. Preoperative urge incontinence was associated with abstinence after surgery (P = .02); postoperative urge incontinence negatively impacted sexual function (P = .047). CONCLUSION Midurethral sling surgery for stress urinary incontinence significantly improves sexual function, although coexistent urge incontinence has a negative impact.