Population-Specific 3D/4D Transperineal Ultrasound Reference Values and Cutoffs Associated With Pelvic Organ Prolapse...

Interpreting pelvic floor imaging and planning management of pelvic organ prolapse (POP) require reliable, population-specific thresholds for levator hiatus evaluation. However, current reference data are largely drawn from Western populations and may not reflect East Asian pelvic anatomy, potentially leading to underdiagnosis and inconsistent risk assessment. This study aimed to define transperineal ultrasound normative measurements and cutoff points associated with clinically significant POP (stage II or higher) in Chinese women.

This multicenter cross-sectional study initially enrolled 706 parous women who underwent urogynecologic assessment at three tertiary hospitals in China between November 2019 and October 2024. After application of the predefined exclusion criteria, 626 women were included in the final analysis. POP was staged with the Pelvic Organ Prolapse Quantification system. Blinded sonographers acquired three- and four-dimensional transperineal ultrasound volumes at rest, maximal contraction, and maximal Valsalva. They measured the levator hiatus area, anteroposterior and lateral diameters, and the levator urethra gap during contraction. Logistic regression examined factors associated with POP stage II or higher, and receiver operating characteristic (ROC) analysis determined optimal thresholds.

Among the 626 women included in the final analysis, the median age was 45 y. A total of 330 participants had POP-Q stage ≥ II, representing 52.7% of the analyzed cohort. Women with advanced prolapse were typically older and had higher parity. Complete levator avulsion and greater levator urethra gap during contraction were more frequent in this group. They also showed larger increases in levator hiatus area and anteroposterior diameter from rest to maximal Valsalva, along with a greater proportional change in the lateral diameter (all p < 0.05). ROC analysis defined key thresholds for detecting POP stage II or higher: absolute LHA at maximal Valsalva ≥19.23 cm² (AUC 0.839), hiatus area change ≥4.85 cm² (AUC 0.805), anteroposterior diameter at maximal Valsalva ≥5.95 cm (AUC 0.798), hiatus area proportional change ≥27.18% (AUC 0.769), levator urethra gap at contraction ≥2.042 cm (AUC 0.696), and lateral diameter proportional change≥15.11% (AUC 0.705).

Population-specific quantitative transperineal ultrasound parameters improved anatomic assessment, enabled earlier identification of high-risk women, and supported individualized surgical planning and conservative management.