Abstract
Introduction and hypothesis
This study was aimed at comparing pelvic floor parameters between the standing and supine positions using upright computed tomography (CT) and evaluating the effects of sex and age in normal healthy volunteers.
Methods
In total, 139 volunteers (70 men, mean 46.7 years; 69 women, mean 47.3 years) underwent both upright CT in the standing position and conventional CT in the supine position. The distances from the bladder neck to the pubococcygeal line (PCL) and anorectal junction (ARJ), defined as the posterior aspect of the puborectalis muscle, to PCL were measured. The length, width, and area of the levator hiatus (LH) were measured on oblique axial images.
Results
The bladder neck (men, 22.2 ± 4.9 mm vs 28.3 ± 5.3 mm; women, 9.0 ± 5.1 mm vs 19.0 ± 4.0 mm) and ARJ (men, −18.8 ± 5.5 mm vs −12.1 ± 5.1 mm; women, −20.0 ± 4.7 mm vs −11.2 ± 4.3 mm) were significantly lower in the standing position than in the supine position (all p < 0.0001). The LH area (men, 1,990 ± 380 mm2 vs 1,697 ± 329 mm2; women, 2,284 ± 344 mm2 vs 1,811 ± 261 mm2) was significantly larger in the standing position (both p < 0.0001). Differences in all parameters between the standing and supine positions were larger in women than in men. ARJ in women showed a significant tendency to descend with age only in the standing position (r = −0.29, p = 0.017).
Conclusions
The bladder neck and ARJ descend and the LH area enlarges in the standing position. Pelvic floor mobility is greater in women than in men. Descent of the ARJ in the standing position is associated with aging in women.
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Funding
This study was supported by the Japan Society for the Promotion of Science (JSPS KAKENHI: Grant Number JP17H04266), Uehara Memorial Foundation, and Canon Medical Systems (Otawara, Japan) for Masahiro Jinzaki.
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K. Narita: data collection, data analysis, manuscript writing; Y. Yamada: protocol development, data collection, manuscript editing; M. Yamada: protocol development, data collection, manuscript editing; Y. Yokoyama: data collection, data analysis, manuscript editing; T. Nakahara: data collection, manuscript editing; M. Jinzaki: project development, manuscript editing.
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Masahiro Jinzaki received a grant from Canon Medical Systems, which loaned the upright CT device to Keio University. The funder was not involved in the design of the study; collection, analysis, and interpretation of the data; or writing of the manuscript. The other authors declare that they have no conflicts of interest.
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Narita, K., Yamada, Y., Yamada, M. et al. Pelvic floor morphology in the standing position using upright computed tomography: age and sex differences. Int Urogynecol J 31, 2387–2393 (2020). https://doi.org/10.1007/s00192-020-04335-z
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DOI: https://doi.org/10.1007/s00192-020-04335-z