Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, MN, USA.
Department of Radiology, Mayo Clinic College of Medicine, Rochester, MN, USA.
Neurogastroenterol Motil. 2018 Jul;30(7):e13314. doi: 10.1111/nmo.13314. Epub 2018 Mar 2.
Endoanal MRI and MR defecography are used to identify anal sphincter injury and disordered defecation. However, few studies have evaluated findings in asymptomatic healthy people. The effects of BMI and parity on rectoanal motion and evacuation are unknown.
In 113 asymptomatic females (age 50 ± 17 years, Mean ± SD) without risk factors for anorectal trauma, anal sphincter appearance, anorectal motion, and pelvic organ prolapse were evaluated with MRI. The relationship between age, BMI, and parity and structural findings were evaluated with parametric and non-parametric tests.
The anal sphincters and puborectalis appeared normal in over 90% of women. During dynamic MRI, the anorectal angle was 100 ± 1º (Mean ± SEM) at rest, 70 ± 2° at squeeze, and 120 ± 2° during defecation. The change in anorectal angle during squeeze (r = -.25, P < .005), but not during evacuation (r = .13, P = .25) was associated with age. In the multivariable models, BMI (P < .01) and parity (P < .01) were, respectively, independently associated with the intersubject variation in the anorectal angle at rest and the angle change during squeeze. Ten percent or fewer women had had descent of the bladder base or uterus 4 cm or more below the pubococcygeal line or a rectocele measuring 4 cm or larger. Only 5% had a patulous anal canal.
In addition to age, BMI and parity also affect anorectal motion in asymptomatic women. These findings provide age-adjusted normal values for rectoanal anatomy and pelvic floor motion.
肛门内磁共振成像（endoanal MRI）和磁共振排粪造影术用于识别肛门括约肌损伤和排便障碍。然而，很少有研究评估无症状健康人群的发现。体质量指数（BMI）和生育对直肠肛门运动和排空的影响尚不清楚。
在 113 名无肛门直肠创伤、肛门括约肌外观、直肠肛门运动和盆腔器官脱垂风险因素的无症状女性（年龄 50±17 岁，均值±标准差）中，通过 MRI 评估其肛门直肠运动。采用参数和非参数检验评估年龄、BMI 和生育与结构发现之间的关系。
超过 90%的女性肛门括约肌和耻骨直肠肌外观正常。在动态 MRI 中，静息时肛门直肠角为 100±1°（均值±SEM），收缩时为 70±2°，排便时为 120±2°。收缩时肛门直肠角的变化（r=-0.25，P<0.005），但排便时无明显变化（r=0.13，P=0.25）与年龄相关。在多变量模型中，BMI（P<0.01）和生育（P<0.01）分别与静息时肛门直肠角的个体间变异性和收缩时的角度变化独立相关。10%或更少的女性膀胱底或子宫下降超过 4cm，低于耻骨尾骨线或直肠前膨出测量值为 4cm 或更大。只有 5%的女性肛门扩约肌松弛。
除年龄外，BMI 和生育也会影响无症状女性的直肠肛门运动。这些发现为直肠肛门解剖和盆底运动提供了年龄调整后的正常数值。
