Levator ani subtended volume: a novel parameter to evaluate levator ani muscle laxity in pelvic organ prolapse

Pre- vs Post-Operative Levator Ani Subtended Volume in Patients Undergoing Hysterectomy: A Comparative Imaging Study

INTRODUCTION AND HYPOTHESIS

The effects of hysterectomy on pelvic floor function remain uncertain, with the levator ani muscle (LAM) playing a critical role in pelvic support. The levator ani subtended volume (LASV) is an objective measure of the LAM's anatomical volume, derived from magnetic resonance imaging (MRI). This study was aimed at assessing the consistency between MRI and computed tomography (CT) in quantifying LASV, and to investigate the effect of hysterectomy on the LAM.

METHODS

This retrospective study analyzed a cohort of 55 hysterectomy patients, utilizing pre-operative pelvic MRI and post-operative CT scans to measure the LASV. To evaluate the consistency between MRI and CT, the study employed the intraclass correlation coefficient and Bland-Altman agreement analysis in a subset of 32 patients with both pre-operative scans. A paired-samplet test was used to analyze LASV changes pre- and post-hysterectomy, and linear regression analysis was performed to account for potential risk factors that may influence post-operative LASV.

RESULTS

High consistency between MRI and CT in measuring LASV was found, with an ICC of 0.911. We observed a significant increase in LASV following hysterectomy, with mean volume pre- and post-operatively of 16.66 cm3 and 18.87 cm3 respectively. Age and body mass index were significant predictors of post-hysterectomy LASV, whereas parity and the type of hysterectomy had no significant impact.

CONCLUSIONS

Hysterectomy significantly affects the LAM, resulting in an increase in post-operative LASV. Moreover, this study verifies that MRI and CT can be used interchangeably for LASV measurements in clinical practice.

Comparison of the anterior pelvis and levator ani muscle on MRI in women with and without anterior pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

The objective was to compare the differences in pelvic and levator ani muscle diameters in women with and without anterior pelvic organ prolapse.

METHODS

Three groups were included, including 50 nulliparous women (nulliparous group), 50 women with stage III-IV anterior vaginal prolapse (prolapse group), and 50 women of the same age as the prolapse group but without prolapse (nonprolapse control group). The ischial interspinous diameter (ISD), anterior pelvic area (APA), levator defect score (LDS), levator ani hiatus width (LH-W), H-line, M-line, levator ani plate length, levator ani plate angle, and cervix length (CL) were measured.

RESULTS

There were no significant differences in ISD (10.6±0.8 vs 10.6±0.9 cm), LH-W (3.0±0.4 vs 3.3±0.4 cm), or CL (2.9±0.6 vs 3.0±0.5 cm) between the nulliparous group and the nonprolapse control group (p>0.05). However, there were significant differences between them and the prolapsed group (11.2±0.6 cm, 3.6±0.4 cm, 4.2±1.5 cm; p<0.05). There were no significant differences in LDS (0.70±0.61 vs 0.70±0.65) or APA (58.4±8.4 vs 60.1±7.4 cm2) between the nonprolapse control group and the prolapse group (p>0.05), but they were significantly different from those of the nulliparous group (0.08±0.34, 55.1±6.0 cm2) (p<0.05). The area under the receiver-operating characteristic curve for the ISD of nonprolapse control and prolapse groups was 0.713, and the cutoff value was 10.95 cm.

CONCLUSIONS

The levator ani hiatus width and cervix length were larger in patients with anterior vaginal prolapse than in those without prolapse. An ischial ISD greater than 10.95 cm was associated with prolapse.

Multimodal measurements of levator bowl volume in nulligravid asymptomatic women: endovaginal ultrasound versus MRI

INTRODUCTION AND HYPOTHESIS

Measurements of levator bowl volume using advanced imaging, may be predictive of pelvic floor muscle function. The aim of this study was to compare the volume of the levator bowl using both magnetic resonance imaging (MRI) and endovaginal ultrasound (EVU) of healthy asymptomatic women.

METHODS

All participants underwent a comprehensive interview including completion of the Pelvic Floor Distress Inventory Questionnaire-20 questionnaire, pelvic examination with a pelvic organ prolapse quantification evaluation, MRI, and EVU. The pelvic floor was segmented using Slicer and the MRI segmentations were trimmed using two methods: soft-tissue landmarks and the field of view (FOV) of the ultrasound volume. The levator bowl volume of the 3D segmented shapes was measured using Blender's 3D printing toolkit. Normality was tested using the Shapiro-Wilks test and comparisons were made using self-paired t tests.

RESULTS

The final analysis included 19 patients. Levator bowl volume measured via MRI was larger than that measured in EVU (46.1 ± 7.9 cm3 vs 27.4 ± 5.9 cm3, p<0.001). Reducing the FOV of the MRI to that of EVU caused the MRI volume to be much closer to the EVU volume (35.5 ± 3.3 cm3 vs 27.4 ± 5.9 cm3, p<0.001); however, it remained significantly larger.

CONCLUSION

Levator bowl volume measured using MRI was larger than that measured using EVU no matter the method of delineation of the levator muscles. Although EVU is safe, cheap, and easy to perform, it captures a smaller volume of levator bowel than MRI.

Hiatal failure: effects of pregnancy, delivery, and pelvic floor disorders on level III factors

INTRODUCTION AND HYPOTHESIS

The failure of the levator hiatus (LH) and urogenital hiatus (UGH) to remain closed is not only associated with pelvic floor disorders, but also contributes to recurrence after surgical repair. Pregnancy and vaginal birth are key events affecting this closure. An understanding of normal and failed hiatal closure is necessary to understand, manage, and prevent pelvic floor disorders.

METHODS

This narrative review was conducted by applying the keywords "levator hiatus" OR "genital hiatus" OR "urogenital hiatus" in PubMed. Articles that reported hiatal size related to pelvic floor disorders and pregnancy were chosen. Weighted averages for hiatal size were calculated for each clinical situation.

RESULTS

Women with prolapse have a 22% and 30% larger LH area measured by ultrasound at rest and during Valsalva than parous women with normal support. Women with persistently enlarged UGH have 2-3 times higher postoperative failure rates after surgery for prolapse. During pregnancy, the LH area at Valsalva increases by 29% from the first to the third trimester in preparation for childbirth. The enlarged postpartum hiatus recovers over time, but does not return to nulliparous size after vaginal birth. Levator muscle injury during vaginal birth, especially forceps-assisted, is associated with increases in hiatal size; however, it only explains a portion of hiatus variation-the rest can be explained by pelvic muscle function and possibly injury to other level III structures.

CONCLUSIONS

Failed hiatal closure is strongly related to pelvic floor disorders. Vaginal birth and levator injury are primary factors affecting this important mechanism.

Hypothesis generation: Quantitative research to levator ani muscle injury based on MRI texture analysis

AIM

Patients with pelvic organ prolapse (POP) mostly have injury to the levator ani muscle (LAM). We aimed to assess LAM injury in POP patients by quantifying texture feature (TF) ratios between the LAM and the obturator internus muscle (OIM) using texture analysis.

METHODS

This study retrospectively enrolled 32 participants, including 24 patients with POP and eight people with normal pelvic floor muscles. TFs of the LAM and the OIM were extracted using LIFEx version 6.30, and an independent samples t-test was performed to determine TF ratios characterizing LAM injury. After dimension reduction and binary logic analysis, the optimal TF ratio was obtained and the LAM injury quantitative evaluation was proposed. Spearman's correlation was performed to explore the correlations between TF ratios and clinical characteristics. We compared the diagnostic performance of quantitative evaluation and visual evaluation.

RESULTS

There were significant differences in 13 TF ratios between the POP and control groups. The area under the receiver operating characteristic curve of the integrated TF ratio was 0.948. Integrated TF ratio was significantly correlated with body mass index, pregnancies, and vaginal deliveries but had no correlation with LAM volume, hiatal area or abortions. Compared with the visual evaluation, the diagnostic accuracy of the quantitative evaluation had improved by 63.2% and 14.3% in the "minor defect" and "major defect" categories, respectively.

CONCLUSION

The integrated TF ratio can be used as a new quantifiable index to characterize LAM injury. The TF evaluation provides a potential role in LAM injury noninvasive diagnostic.

Prevalence of symptoms of pelvic floor dysfunction and related factors among Japanese female healthcare workers

OBJECTIVES

Women working in the medical field may be at risk for pelvic floor dysfunction due to high physical activity levels leading to increased abdominal pressure; however, the actual situation remains unknown. This study aimed to clarify the prevalence of symptoms of pelvic floor dysfunction and its associated factors among Japanese women working in the medical field.

METHODS

A cross-sectional study was conducted among female employees at a public hospital in Japan from July to August 2020. Participants answered a web-based questionnaire. Three types of symptoms related to pelvic floor dysfunction were assessed based on one or more subscale scores in the Pelvic Floor Distress Inventory-Short Form 20 (PFDI-20).

RESULTS

Out of 466 female employees in the hospital, 294 responded (response rate 63.1%). The mean age was 42.8 ± 10.3 years old and 221 (73.5%) were nurses. The prevalence of at least one type of symptom was 63.9%. The prevalence of recto-anal symptoms (45.9%) was highest, followed by lower urinary tract (37.1%) and pelvic organ prolapse symptoms (22.8%). The total PFDI-20 score was associated with constipation (β = .254), body mass index (β = .136), and part-time work (β = .167) after adjusting for other variables.

CONCLUSION

This study showed a high prevalence of symptoms related to pelvic floor dysfunction among women working in the medical field. Lifestyle management to prevent constipation and obesity is a promising strategy to improve symptoms of pelvic floor dysfunction.

Estimated Levator Ani Subtended Volume: A Predictive Biomarker for Surgical Outcomes Following Native Tissue Apical Repair

OBJECTIVE

The aim of the study was to investigate the clinical utility of estimated levator ani subtended volume (eLASV) as a prospective preoperative biomarker for prediction of surgical outcomes.

STUDY DESIGN

This is a prospective case-control pilot study. Patients were recruited and gave consent between January 2018 and December 2020. Surgical failure was defined by composite score. The eLASV was calculated for each patient based on a previously published algorithm. Descriptive statistics, Fisher exact test, log-binomial regression, area under a receiver operating characteristics, Bland-Altman plot, Lin coefficient, and κ coefficient were all performed for analysis.

RESULTS

Fifty-one patients gave consent, 31 completed preoperative magnetic resonance imaging, 27 underwent surgery (uterosacral ligament suspension), and 19 followed up for 1-year examination. Five patients (26.3%) were defined as surgical failure with median eLASV volume of 57.0 (interquartile range, 50.1-66.2). Fourteen patients (73.7%) were defined as surgical success with median eLASV of 28.2 (interquartile range, 17.2-24.3). Eighty percent of the surgical failure group (4/5) had elevated volume of eLASV, where only 14.3% of the success group (2/14) had an elevated volume (P = 0.0173). No confounders were found and unadjusted log-binomial regression suggested that patients with a high eLASV were 8.7 (95% confidence interval, 1.2-61.9) times more likely to experience surgical failure compared with those with low eLASV. The c-statistic (area under a receiver operating characteristics) was high at 0.829 along with Lin concordance coefficient of 0.949 (95% confidence interval, 0.891-0.977) for continuous data between the 2 interrater observer teams.

CONCLUSIONS

In this small prospective pilot study, patients with elevated eLASV on a preoperative pelvic magnetic resonance imaging were associated with an increased risk for surgical failure at 1 year regardless of age, body mass index, stage, or parity.CLINICAL TRIAL REGISTRATION:ClinicalTrials.gov, NCT03534830.

Three-Dimensional Pelvic Floor Ultrasound Assessment of Pelvic Organ Prolapse: Minimal Levator Hiatus and Levator Ani Deficiency Score

Purpose

The purpose of this study was to determine whether levator ani deficiency (LAD) scores and minimal levator hiatus (MLH) areas affect Pelvic Organ Prolapse Quantification (POP-Q) stage.

Methods

This study was a retrospective chart review of patients with pelvic organ prolapse (POP) at Seoul Songdo Hospital between August 2019 and August 2020. Three-dimensional (3D) pelvic floor ultrasound, preoperative anal manometry, and other physiological tests were performed in 78 patients with POP symptoms. We divided the patients into mild prolapse and severe prolapse groups based on the POP-Q. We examined the LAD and MLH areas. LAD scores were categorized as mild, moderate, or severe.

Results

There were 32 patients (41.0%) in the mild prolapse group (POP-Q stage I and II) and 46 (59.0%) in the severe prolapse group (POP-Q stage III and IV). The mean LAD score was significantly higher in severe prolapse group (13.33±2.49 vs. 8.19±2.92, P<0.001), and the rate of severe deficiency was also significantly higher in the severe prolapse group (29 [63.0%] vs. 2 [6.3%], P<0.001). The mean MLH was also significantly larger in the severe prolapse group (17.91±2.74 cm² vs. 14.95±2.60 cm², P<0.001). In addition, both MLH and LAD scores tended to increase at each stage.

Conclusion

There is a strong positive correlation between the POP-Q stage and the MLH and LAD scores that can be seen on 3D pelvic floor ultrasound. The findings of this study, by objectively demonstrating LAD and MLH in women with POP, are an important contribution to POP.

Levator ani muscle (LAM) anatomical volume compared to age and body mass index (BMI) of patients

INTRODUCTION AND HYPOTHESIS

The levator ani muscle (LAM) plays an important role in pelvic support. Estimated levator ani subtended volume (eLASV) is an objective measurement of the anatomical volume of the LAM obtained from pelvic MRIs. The aim of this study was to assess the relationship between the anatomical volume of LAM to the age and body mass index (BMI) of a surgical patient based on our previous published cutoff value of increased LAM volume as measured by pelvic MRIs (eLASV > 38.5). We hypothesize that increasing age and BMI will both be correlated with the increasing volumes of LAM.

METHODS

We conducted a secondary analysis of an Institutional Review Board-approved retrospective cohort study. Standard protocol pelvic MRI measurements, including the pubococcygeal line, H-line, and M-line, were collected along with the calculated width of the levator ani hiatus (eLASV = - 72.838 + 0.598H-line + 1.217 M-line + 1.136WLH). Comparison to patients' age and BMI was assessed using the Wilcoxon-Mann-Whitney (continuous) and chi-square test (group). Spearman's correlation analysis was used to explore the relationship between age and BMI to eLASV.

RESULTS

Patients with elevated LAM volumes of eLASV were more likely to be older than patients with low volume of LAM, with median age 65 (37, 83) vs. 49.5 (28, 72), respectively (p < 0.001). We observed no difference in median BMI between patients with elevated volumes of eLASV compared with patients with low volumes of eLASV.

CONCLUSIONS

Increasing age of women appears to be directly related to elevated volumes for levator ani muscle morphology when measured with eLASV.

Levator bowl volume during straining and its relationship to other levator measures

INTRODUCTION AND HYPOTHESIS

This study was aimed at measuring levator ani bowl volume at rest and while straining, comparing women with and without prolapse (controls), and assessing the ability of measures of the mid-sagittal bowl area, levator hiatus (LH), and urogenital hiatus (UGH) to predict bowl volume.

METHODS

Forty MRI scans previously acquired in case-control prolapse studies, including 20 women with prolapse and 20 women without prolapse, of similar age and parity, were selected. 3D models of rest and strain bowl volumes were made using sagittal scans and 3D Slicer®. Mid-sagittal bowl area, UGH, and LH were measured using ImageJ. Data were analyzed using two sample t tests, effect sizes, and Pearson's correlation coefficients at the 0.05 significance level.

RESULTS

Data were acquired in a total of 40 total women. Levator bowl volume at strain had a correlation coefficient of 0.5 with bowl volume at rest. During straining, prolapse subjects had a 53% larger bowl volume than control subjects (254 ± 86 cm³ vs 166 ± 44 cm³, p < 0.001), but at rest, the difference was 34% (138 ± 40 cm³ vs 103 ± 25 cm³, p = 0.002). Effect sizes for all parameters were large (d > 0.75). The strongest correlation with straining bowl volume was mid-sagittal straining bowl area (r = 0.86), followed by LH strain (r = 0.80), then UGH strain (r = 0.76).

CONCLUSIONS

Straining levator bowl volume is substantially different than measures made at rest, with only a quarter of straining values explained by resting measurements. The bowl area at strain is the best 2D measurement estimating bowl volume and explains 74% of straining bowl volume.

Recommended standardized terminology of the anterior female pelvis based on a structured medical literature review

BACKGROUND

The use of imprecise and inaccurate terms leads to confusion amongst anatomists and medical professionals.

OBJECTIVE

We sought to create recommended standardized terminology to describe anatomic structures of the anterior female pelvis based on a structured review of published literature and selected text books.

STUDY DESIGN

We searched MEDLINE from its inception until May 2, 2016, using 11 medical subject heading terms to identify studies reporting on anterior female pelvic anatomy; any study type published in English was accepted. Nine textbooks were also included. We screened 12,264 abstracts, identifying 200 eligible studies along with 13 textbook chapters from which we extracted all pertinent anatomic terms.

RESULTS

In all, 67 unique structures in the anterior female pelvis were identified. A total of 59 of these have been previously recognized with accepted terms in Terminologia Anatomica, the international standard on anatomical terminology. We also identified and propose the adoption of 4 anatomic regional terms (lateral vaginal wall, pelvic sidewall, pelvic bones, and anterior compartment), and 2 structural terms not included in Terminologia Anatomica (vaginal sulcus and levator hiatus). In addition, we identified 2 controversial terms (pubourethral ligament and Grafenberg spot) that require additional research and consensus from the greater medical and scientific community prior to adoption or rejection of these terms.

CONCLUSION

We propose standardized terminology that should be used when discussing anatomic structures in the anterior female pelvis to help improve communication among researchers, clinicians, and surgeons.

Interactions among pelvic organ protrusion, levator ani descent, and hiatal enlargement in women with and without prolapse

BACKGROUND

Pelvic organ prolapse has 2 components: (1) protrusion of the pelvic organs beyond the hymen; and (2) descent of the levator ani. The Pelvic Organ Prolapse Quantification system measures the first component, however, there remains no standard measurement protocol for the second mechanism.

OBJECTIVE

We sought to test the hypotheses that: (1) difference in the protrusion area is greater than the area created by levator descent in prolapse patients compared with controls; and (2) prolapse is more strongly associated with levator hiatus compared to urogenital hiatus.

STUDY DESIGN

Midsagittal magnetic resonance imaging scans from 30 controls, 30 anterior predominant, and 30 posterior predominant prolapse patients were assessed. Levator area was defined as the area above the levator ani and below the sacrococcygeal inferior pubic point line. Protrusion area was defined as the protruding vaginal walls below the levator area. The levator hiatus and urogenital hiatus were measured. Bivariate analysis and multiple comparisons were performed. Bivariate logistic regression was performed to assess prolapse as a function of levator hiatus, urogenital hiatus, levator area, and protrusion. Pearson correlation coefficients were calculated.

RESULTS

The levator area for the anterior (34.0 ± 6.5 cm²) and posterior (35.7 ± 8.0 cm²) prolapse groups were larger during Valsalva compared to controls (20.9 ± 7.8 cm², P < .0001 for both); similarly, protrusion areas for the anterior (14.3 ± 6.2 cm²) and posterior (14.4 ± 5.7 cm²) prolapse groups were both larger compared to controls (5.0 ± 1.8 cm², P < .0001 for both). The levator hiatus length for the anterior (7.2 ± 1 cm) and posterior (6.9 ± 1 cm) prolapse groups were longer during Valsalva compared to controls (5.2 ± 1.5 cm, P < .0001 for both); similarly, urogenital hiatus lengths for the anterior (5.7 ± 1 cm) and posterior (6.3 ± 1.1 cm) prolapse groups were both longer than controls (3.8 ± 0.8 cm, P < .0001 for both). The difference in levator area in prolapse patients compared with controls was greater than the difference in protrusion area (14.0 ± 7.2 cm² vs 9.4 ± 5.9 cm², P < .0002). The urogenital hiatus was more strongly associated with prolapse than the levator hiatus (odds ratio, 12.9; 95% confidence interval, 4.1-39.2, and odds ratio, 4.3; 95% confidence interval, 2.3-7.5). Levator hiatus and urogenital hiatus are both correlated with levator and protrusion areas, and all were associated with maximum prolapse size (P ≤ .001, for all comparisons).

CONCLUSION

In prolapse, the levator area increases more than the protrusion area and both the urogenital hiatus and levator hiatus are larger. The odds of prolapse for an increase in the urogenital hiatus are 3 times larger than for the levator hiatus, which leads us to reject both the original hypotheses.

Levator Ani Muscle Defects in Patients With Surgical Failure

INTRODUCTION

The objective of the study was to use a well-described system of measuring levator ani (LA) muscle defects from magnetic resonance images to evaluate whether major defects are correlated to an increased risk of surgical failure.

METHODS

A retrospective cohort study performed on patients who underwent laparoscopic uterosacral ligament suspension from 2010 to 2012. Surgical failure was defined as a composite score of anatomic bulge beyond the hymen with sensation of bulge or repeat treatment of prolapse via pessary or surgery by 1-year follow-up. Levator ani muscle defects were graded by a score of 0 (no defect), 1 (<50% muscle bulk missing), 2 (>50% muscle bulk missing), or 3 (complete loss of muscle). Total score is the sum from both graded sides, with 0 classified as having no defect, 1 to 3 classified as having minor defects, and 4 to 6 classified as having major defects. Dichotomous values of LA major defects were compared against dichotomous values of surgical outcomes via a contingency table. Fisher exact test was then performed to correlate major defects to surgical success/failure. P value of less than 0.05 was considered statistically significant.

RESULTS

Sixty-six women met the inclusion criteria. Thirteen (19.6%) patients met the criteria for surgical failure at 1 year. Of the 13, 54% (7) had a major defect, and 46% (6) had a minor or no defect (odds ratio, 1.31; 95% confidence interval, 0.39-4.41; P = 0.762).

CONCLUSIONS

We did not find a statistical correlation to surgical failure after a laparoscopic uterosacral ligament suspension with LA muscle defects on preoperative magnetic resonance images within this specific patient population.

Estimated levator ani subtended volume: a novel assay for predicting surgical failure after uterosacral ligament suspension

BACKGROUND

Levator ani muscle complex plays an important role in pelvic support and defects or laxity in this muscle complex contributes to pelvic organ prolapse and recurrence after surgical repair.

OBJECTIVE

The purpose of this study was to determine whether estimated levator ani subtended volume can predict surgical outcomes for laparoscopic bilateral uterosacral ligament suspension.

STUDY DESIGN

A retrospective cohort study was performed in patients who underwent laparoscopic uterosacral ligament suspension from 2010-2012. Only patients with a preoperative pelvic magnetic resonance image were included. Surgical failure was defined as a composite score that included the presence of anatomic bulge beyond the hymen with sensation of vaginal bulge or repeat treatment for prolapse via pessary or surgery by 1-year follow-up evaluation. Standard protocol pelvic magnetic resonance imaging measurements pubococcygeal line, H-line, and M-line were collected along with the calculation of the width of the levator ani hiatus. Estimated levator ani subtended volume was calculated for each subject. An optimal cutoff point was calculated and compared against categoric values of surgical success/failure. A Fisher exact test, an area under receiver operating characteristics curve, and logistic regression analysis were performed. A probability value of <.05 was considered statistically significant.

RESULTS

Ninety-three women underwent laparoscopic bilateral uterosacral ligament suspension during study period. Of these, 66 women had a standardized preoperative pelvic magnetic resonance image per institutional protocol. Thirteen patients (19.6%) met the criteria for surgical failure by 1 year. An optimal cutoff point of 38.5 was calculated by Liu's method for optimization. Among the patients with defined surgical failures, 84.6% (11/13) had an estimated levator ani subtended volume above cutoff point of 38.5. Among the patients with defined surgical success, 39.6% (21/53) had an estimated levator ani subtended volume above the cutoff point (84.6% vs 39.6%; P = .0048) with a significant odds ratio of 8.38 (95% confidence interval, 1.69-41.68; P = .009). An area under receiver operating characteristics curve of 0.725 (95% confidence interval, 0.603-0.847), sensitivity of 84.6% (95% confidence interval, 54.6%-98.1%), and specificity of 60.4% (95% confidence interval, 46%-73.5%) at 38.5 were predictors of surgical success/failure by 1 year. Logistic regression analysis demonstrated no significant confounders among age, body mass index, stage, or parity.

CONCLUSIONS

Estimated levator ani subtended volume may predict surgical failure for laparoscopic bilateral uterosacral ligament suspension. Patients with a calculated estimated levator ani subtended volume above 38.5 on a preoperative pelvic magnetic resonance imaging were associated with an increased risk for surgical failure by 1 year, regardless of age, body mass index, stage, or parity. Future investigation that will include repeatability, reliability analysis, and a prospective study is warranted.

A logarithmic opinion pool based STAPLE algorithm for the fusion of segmentations with associated reliability weights

Pelvic floor dysfunction is common in women after childbirth and precise segmentation of magnetic resonance images (MRI) of the pelvic floor may facilitate diagnosis and treatment of patients. However, because of the complexity of its structures, manual segmentation of the pelvic floor is challenging and suffers from high inter and intra-rater variability of expert raters. Multiple template fusion algorithms are promising segmentation techniques for these types of applications, but they have been limited by imperfections in the alignment of templates to the target, and by template segmentation errors. A number of algorithms sought to improve segmentation performance by combining image intensities and template labels as two independent sources of information, carrying out fusion through local intensity weighted voting schemes. This class of approach is a form of linear opinion pooling, and achieves unsatisfactory performance for this application. We hypothesized that better decision fusion could be achieved by assessing the contribution of each template in comparison to a reference standard segmentation of the target image and developed a novel segmentation algorithm to enable automatic segmentation of MRI of the female pelvic floor. The algorithm achieves high performance by estimating and compensating for both imperfect registration of the templates to the target image and template segmentation inaccuracies. A local image similarity measure is used to infer a local reliability weight, which contributes to the fusion through a novel logarithmic opinion pooling. We evaluated our new algorithm in comparison to nine state-of-the-art segmentation methods and demonstrated our algorithm achieves the highest performance.

Are bony pelvis dimensions associated with levator ani defects? A case-control study

INTRODUCTION AND HYPOTHESIS

Bony pelvis dimensions have been shown to differ in women with and without pelvic floor dysfunction. The goal of this study was to determine whether bony pelvis dimensions are different when comparing women with severe bilateral levator ani defects (LAD) with those with normal muscles.

METHODS

This is a secondary analysis of a case-control study comparing women with and those without pelvic organ prolapse. Subjects underwent pelvic organ prolapse quantification (POP-Q) examination and were classified as either having prolapse or being normal. All underwent pelvic magnetic resonance imaging (MRI). Levator defects were assessed based on the muscles' appearance on imaging and subjects were stratified into two groups--women with normal muscles (n = 99) and women with severe bilateral LAD (n = 50). Bony pelvis dimensions were measured via MRI pelvimetry. The subpubic angle, interspinous and intertuberous diameters, and the sacrococcygeal joint-to-infrapubic point (SCIPP) lengths were compared.

RESULTS

Both groups had similar demographics. The SCIPP length was 2.5 % (3 mm) shorter in women with severe LAD than in those without defects (P = 0.02). The SCIPP measured 4 % (5 mm) less in women with prolapse and severe LAD than in subjects with prolapse but normal muscles (P = 0.01). Logistic regression identified SCIPP length and history of forceps delivery as being independent predictors of severe bilateral LAD.

CONCLUSIONS

Severe bilateral LAD are associated with shorter SCIPP length and forceps-assisted vaginal delivery.

Geriatric gynecology

Most postmenopausal vaginal bleeding is benign; however, it merits diagnostic evaluation by transvaginal ultrasound or endometrial biopsy after emergency department evaluation. Patients and physicians may treat menopausal symptoms with hormone replacement therapy or other agents, such as venlafaxine or gabapentin. Hormone replacement therapy, when initiated close to the start of menopause and continued at the lowest possible dose for the shortest possible duration, carries less risk than previously believed. Pelvic organ prolapse affects millions of women and may contribute to poor body image and difficulty with urinary, gastrointestinal, and sexual function. Treatment options include Kegel exercises, pessaries, and surgery.