Diagnostic Accuracy of Transvaginal Ultrasound Versus Magnetic Resonance Imaging for Deep Infiltrating Endometriosis: A Histopathologically Correlated Prospective Study

BackgroundDeep infiltrating endometriosis (DIE) requires accurate anatomical assessment.This study prospectively compared transvaginal ultrasound (TVUS) and magnetic resonance imaging (MRI) with histopathology as the reference standard. MethodsIn this prospective paired diagnostic-accuracy study, 350 women with clinically suspected DIE underwent standardized TVUS and pelvic MRI, followed by laparoscopy and histopathological assessment.We computed overall and anatomical site-specific sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy, and likelihood ratios.We compared paired classifications using McNemar's test. ResultsHistopathology confirmed DIE in 213 (60.9%) participants.TVUS demonstrated 89.2% sensitivity, 86.9% specificity, 91.3% PPV, 83.8% NPV, and 88.3% accuracy.Corresponding MRI estimates were 91.5%, 92.7%, 95.1%, 87.6%, and 92.0%, respectively.TVUS showed higher sensitivity for ureteric disease, whereas MRI showed higher specificity and accuracy for several other anatomical sites.Paired classifications showed no significant differences (McNemar's χ² = 0.066, P = 0.798), although the counts differed.Interobserver agreement was substantial to near-perfect for most sites. ConclusionBoth standardized TVUS and MRI demonstrated high diagnostic accuracy for DIE.MRI performed better numerically for several measurements, but the paired analysis did not show statistically significant differences in overall classification.Expert TVUS may serve as an effective first-line examination, with MRI providing complementary information for complex, extensive, or equivocal disease and preoperative mapping.