Magnetic resonance imaging to evaluate anterior pelvic prolapse: H line is the key

The aim of the study is to compare clinical staging of anterior pelvic prolapse with magnetic resonance imaging (MRI) staging, using the pubococcygeal line (PCL), the midpubic line (MPL), and the H line as reference lines. Moreover, we aim to analyze interrater reliability of each reference line.

Forty-two women with pelvic organ prolapse (POP) symptoms were studied using the pelvic organ prolapse quantification on physical examination. Two different observers calculated anterior POP using the three MRI reference lines, retrospectively. Agreement between MRI and clinical staging was estimated using Pearson correlation for the quantitative measurements and kappa index for the stages. Interrater reliability was estimated using the intraclass correlation coefficient (ICC).

Correlation between physical examination and the H line was high by both observers (r = 0.86 and r = 0.76, p < 0.01). The correlation was lower using MPL (r = 0.76 and r = 0.65, p < 0.01). The results of comparing MRI staging and physical examination were: κ = 0.618 and κ = 0.602 for the H line, κ = 0.273 and κ = 0.267 for MPL and κ = -0.105 and κ = -0.140 for PCL. The results of interrater reliability were: ICC of 0.968 for the H line, ICC of 0.788 for MPL, and ICC of 0.737 for PCL.

Anterior POP staging using MRI H line as a reference presents a better agreement with clinical staging than PCL or MPL. The H line has better interrater reliability. The H line could replace the current lines.