Second-line MRI after expert transvaginal ultrasound in selected patients with suspected complex deep endometriosis: A prospective cohort study

Introduction

The objective of this study was to evaluate the added diagnostic yield of second-line magnetic resonance imaging (MRI) after expert transvaginal ultrasound (TVS) for preoperative mapping of deep endometriosis (DE). Material and methods: In this prospective observational cohort study, women with suspected DE scheduled for surgery after expert ultrasound were included. TVS was performed according to the International Deep Endometriosis Analysis (IDEA) protocol. MRI was selectively performed as a second-line investigation in patients with suspected advanced disease, inconclusive TVS, or advanced symptoms despite negative TVS findings. Surgical visualization served as the primary reference standard, with histopathology used as a secondary reference standard when available. Diagnostic performance (sensitivity, specificity, predictive values, likelihood ratios, and Cohen's κ) was assessed for TVS, MRI, and their combination, and stratified by prior surgical status. For the combined approach, a positive result was defined as a positive finding on either modality (TVS or MRI), representing a rule-out strategy.