Female Pelvic Medicine and Reconstructive Surgery, Michigan Medicine, Ann Arbor, MI; Female Pelvic Medicine and Reconstructive Surgery, Rush University Medical Center, Chicago, IL; Society for Gynecologic Surgeons Pelvic Anatomy Group.
Female Pelvic Medicine and Reconstructive Surgery, University Hospitals Cleveland Medical Center/Metro Health Medical Center, Cleveland, OH; Society for Gynecologic Surgeons Pelvic Anatomy Group.
Am J Obstet Gynecol. 2019 Nov;221(5):521.e1-521.e7. doi: 10.1016/j.ajog.2019.08.001. Epub 2019 Aug 8.
An increase in size of the aperture of the pelvis that must be spanned by pelvic floor support structures translates to an increase in the force on these structures. Prior studies have measured the bony dimensions of the pelvis, but the effect of changes in muscle bulk that may affect the size of this area are unknown.
To develop a technique to evaluate the aperture size in the anterior pelvis at the level of the levator ani muscle attachments, and to identify age-related changes in women with and without prolapse.
This was a technique development and pilot case-control study evaluating pelvic magnetic resonance imaging from 30 primiparous women from the Michigan Pelvic Floor Research Group MRI Data Base: 10 younger women with normal support, 10 older women with prolapse, and 10 older menopausal women without prolapse. Anterior pelvic area measurements were made in a plane that included the bilateral ischial spines and the inferior pubic point, approximating the level of the arcus tendineus fascia pelvis. Measurements of the anterior pelvic area, obturator internus muscles, and interspinous diameter were made by 5 independent raters from the Society of Gynecologic Surgeons Pelvic Anatomy Group who focused on developing pelvic imaging techniques, and evaluating interrater reliability. Demographic characteristics were compared across groups of interest using the Wilcoxon rank sum test, χ, or Fisher exact test where appropriate. Multiple linear regression models were created to identify independent predictors of anterior pelvic area.
Per the study design, groups differed in age and prolapse stage. There were no differences in race, height, body mass index, gravidity, or parity. Patients with prolapse had a significantly longer interspinous diameter, and more major (>50% of the muscle) levator ani defects when compared to both older and younger women without prolapse. Interrater reliability was high for all measurements (intraclass correlation coefficient = 0.96). The anterior pelvic area (cm) was significantly larger in older women with prolapse compared to older (60 ± 5.1 vs 53 ± 4.9, P = .004) and younger (60 ± 5.1 vs 52 ± 4.6, P = .001) women with normal support. The younger and older women with normal support did not differ in anterior pelvic area (52 ± 4.6 vs 53 ± 4.9, P = .99). After adjusting for race and body mass index, increased anterior pelvic area was significantly associated with the following: being an older woman with prolapse (β = 6.61 cm, P = .004), and interspinous diameter (β = 4.52 cm, P = .004).
Older women with prolapse had the largest anterior area, suggesting that the anterior pelvic area is a novel measure to consider when evaluating women with prolapse. Interspinous diameter, and being an older woman with prolapse, were associated with a larger anterior pelvic area. This suggests that reduced obturator internus muscle size with age may not be the primary factor in determining anterior pelvic area, but that pelvic dimensions such as interspinous diameter could play a role. The measurements were highly repeatable. The high intraclass correlation coefficient indicates that all raters were able to successfully learn the imaging software and to perform measurements with high reproducibility.
骨盆开口的大小必须由骨盆底支撑结构跨越，这会导致这些结构上的力增加。先前的研究已经测量了骨盆的骨骼尺寸，但肌肉体积变化对该区域大小的影响尚不清楚。
开发一种评估提肛肌附着处水平前骨盆开口大小的技术，并确定有和没有脱垂的女性的年龄相关变化。
这是一项技术开发和试点病例对照研究，评估了密歇根骨盆底研究小组 MRI 数据库中的 30 名初产妇的骨盆磁共振成像：10 名年轻、有正常支撑的女性，10 名年长、有脱垂的女性，和 10 名年长、绝经、无脱垂的女性。在前骨盆区域测量中，包括双侧坐骨棘和耻骨下点在内的平面，近似于骨盆弧形腱膜的水平。前骨盆区域、闭孔内肌和棘间直径的测量由来自妇科外科研讨会骨盆解剖组的 5 名独立评估员进行，他们专注于开发骨盆成像技术，并评估评估者间的可靠性。使用 Wilcoxon 秩和检验、卡方检验或 Fisher 确切检验（适当时）比较感兴趣组之间的人口统计学特征。创建多元线性回归模型以确定前骨盆区域的独立预测因子。
根据研究设计，各组在年龄和脱垂阶段上存在差异。种族、身高、体重指数、孕次和产次无差异。与年长和年轻无脱垂女性相比，脱垂患者的棘间直径明显更长，且更大比例（>50%的肌肉）的肛提肌缺陷。所有测量的评估者间可靠性均很高（组内相关系数=0.96）。与年长（60±5.1 比 53±4.9，P=0.004）和年轻（60±5.1 比 52±4.6，P=0.001）有正常支撑的女性相比，有脱垂的年长女性的前骨盆区域（cm）明显更大。有正常支撑的年轻和年长女性的前骨盆区域无差异（52±4.6 比 53±4.9，P=0.99）。在校正种族和体重指数后，前骨盆区域的增加与以下因素显著相关：是有脱垂的年长女性（β=6.61cm，P=0.004）和棘间直径（β=4.52cm，P=0.004）。
有脱垂的年长女性的前骨盆区域最大，这表明前骨盆区域是评估脱垂女性的一种新的考虑因素。棘间直径和年长女性有脱垂与更大的前骨盆区域相关。这表明，随着年龄的增长，闭孔内肌体积减小可能不是决定前骨盆区域的主要因素，但骨盆尺寸（如棘间直径）可能起作用。该测量具有高度可重复性。高组内相关系数表明，所有评估者都能够成功学习成像软件，并以高度可重复性进行测量。
