Does Surgery for Prolapse Change the Genital and Levator Hiatus on MRI?

INTRODUCTION: Prior studies have suggested that a clinically enlarged genital hiatus (GH) after surgery may be a risk factor for prolapse recurrence (Vaughan et al. 2018, Bradley et al 2023). What remains unknown is whether surgery can change the measurements of the levator hiatus (LH) and urogenital hiatus (UGH) made on magnetic resonance imaging (MRI) in patients with prolapse. OBJECTIVE: To describe the changes in LH and UGH length and cross-sectional area before and after surgery for prolapse. METHODS: Twenty subjects with anterior predominant prolapse who were planning surgical repair underwent an MRI preoperatively and postoperatively. The method of surgical repair was individualized for each subject as determined by their surgeon. Using 3DSlicer software (www.slicer.org), six raters measured LH and UGH length in the mid-sagittal plane, and LH and UGH area in a reformatted axial plane (Figure 1). Pre- and postoperative measurements were compared using the Wilcoxon signed-rank test. Interrater reliability was calculated using the intraclass correlation coefficient (ICC). RESULTS: 20 patients were included in the final analysis. The ICCs for all measurements ranged from 0.7 to 0.9, indicating moderate to excellent interrater reliability; therefore, all rater measurements were averaged for analysis. The patients had a median age of 64 (IQR 55.4–69.8), median BMI of 28.1 (IQR 24–31.4), and median parity of 3 (IQR 2–4). The most common apical support procedure was a sacrospinous ligament suspension (n=6, 30%), followed by a uterosacral ligament suspension (n=5, 25%). Most patients underwent an anterior vaginal repair (n=19, 95%) and a posterior repair (n=17, 85%). Fourteen patients (70%) underwent a vaginal hysterectomy, and six had concurrent anti-incontinence procedures, with five (25%) midurethral slings and one (5%) Kelly plication (Table 1). UGH area was significantly smaller following surgery (23.5 cm 2 pre vs 21.7 cm2 post, p<.001). There were no significant postoperative changes in LH length (66.9 mm pre vs 67.8 mm post, p=.4), LH area (26.5 cm2 pre vs 25.8 cm2 post, p=.37), and UGH length (51.9 mm pre vs 51.3 mm post, p=.65). CONCLUSIONS: UGH area was the only measure that significantly decreased after surgery for prolapse, while UGH length, LH area, and LH length remained unchanged. This suggests that while prolapse surgeries improve symptoms and quality of life for patients, there may be persistent, postoperative underlying defects in pelvic support that can play a role in the risk of prolapse recurrence.Figure 1Figure 2Table 1