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

ABSTRACT

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.