Assessment of pelvic organ prolapse with the Pelvic Inclination Correction System: defining the normal range and threshold to pathology

Abstract Purpose To define the normal range and threshold values for pathologic prolapse on MRI using the PICS line and assess its correlation with the pubococcygeal line (PCL). Methods This prospective, IRB-approved study included 20 nulliparous volunteers and 18 prolapse patients (POP-Q Stage ≥ 2). Organ positions (bladder, cervix, anorectal junction) relative to PICS and PCL were measured on dynamic MRI. Differences in organ position were compared. Receiver-operating characteristic (ROC) analysis was performed to identify cutoff values for prolapse using the PICS line. The correlation between PICS and PCL measurements was tested with Spearman’s rank correlation. Results In volunteers, median bladder and cervix positions measured to the PICS at rest were − 2.7 cm and − 5.3 cm compared to − 1.9 cm and − 2.7 cm in patients ( p < 0.001). During straining, bladder and cervix were at − 0.9 cm and − 3.2 cm in volunteers versus + 2.5 cm and + 2.5 cm in patients ( p < 0.001). Correlation was strong for PICS and PCL measurements for all three compartments ( δ = 0.883–0.970, p ≤ 0.001). AUCs of PICS for the anterior and middle compartment were 0.98 (95% confidence interval CI 0.96–1.00, p < 0.001) and 0.96 (95% CI 0.89–1.00, p < 0.001) for differentiating patients from healthy volunteers. AUC for the posterior compartment was 0.76 (95% CI 0.57–0.96, p = 0.034). Conclusion PICS measurements reliably differentiate patients from volunteers in the anterior and middle compartment. Future studies need to identify a reliable threshold for the posterior compartment. PICS and PCL measurements are strongly correlated. Graphical abstract