Quantitative Comparison of Ultrasound Versus Magnetic Resonance Imaging for Uterine Fibroid Mapping Before Myomectomy [ID 1484]

INTRODUCTION: Myomectomy is the gold standard for surgical removal of uterine leiomyomas. Evidence-based research exploring the accuracy of ultrasound (US) compared to magnetic resonance imaging (MRI) for preoperative mapping of uterine fibroids is limited. METHODS: A retrospective chart review was conducted to assess patients who underwent laparoscopic robotic-assisted myomectomy for symptomatic uterine fibroids at a single institution, by a single surgeon, from 2013 to 2023. Imaging, intraoperative, and postoperative outcomes were abstracted from medical records. Mann–Whitney U tests and two sample t-tests were used to compare differences by fibroid type (subserosal, intramural, submucosal) between preoperative imaging and operative findings of fibroid 1) number, 2) size, and 3) number multiplied by size, a metric capturing magnitude of error. RESULTS: A total of 165 patients (M age 37.4, 85.5% Black) were included in analyses. Both US and MRI (n=68, 41.2%) and MRI-only (n=68, 41.2%) were utilized for preoperative fibroid mapping for most patients, whereas fewer patients received US-only (n=29, 17.6%). Magnetic resonance imaging detected a greater number of fibroids (M 4.26, SD 3.71) than US (M 2.30, SD 1.62), but both underestimated operative findings (M 6.18, SD 5.84). We observed no significant difference between imaging modalities in predicting operative fibroid number or size. Magnetic resonance imaging had a smaller magnitude of error (ie, number*size) compared to US ( P =.03) for intramural fibroids. CONCLUSIONS/IMPLICATIONS: Among patients undergoing laparoscopic myomectomy, we observed minimal differences in the margin of error of US versus MRI in preoperative fibroid mapping for both number and size. Magnetic resonance imaging may have a smaller magnitude of error for intramural fibroids.