OBJECTIVES: To assess the added value of magnetic resonance imaging (MRI) after dynamic transvaginal ultrasound (TVUS) in the diagnostic pathway for preoperative staging of pelvic endometriosis. METHODS: A prospective observational study was conducted between April 22, 2014, and May 1, 2015. During that period, 363 patients with a clinical suspicion of endometriosis were included. All patients underwent a history, clinical examination, and dynamic TVUS examination. Most of the patients (n = 274) underwent conservative treatment according to the European Society of Human Reproduction and Embryology guidelines. Eighty-nine patients were selected for surgery, of whom 72 patients underwent the complete diagnostic pathway: ie, history, clinical examination, dynamic TVUS, and MRI. All data were analyzed by the nonparametric McNemar test for comparing each step in the diagnostic algorithm. RESULTS: The sensitivity and specificity for the history, pelvic examination, and dynamic TVUS were 93.7% and 55.6% (P < .001), respectively; when MRI findings were included, the sensitivity and specificity were 85.9% and 62.5%. Adding MRI routinely to the diagnostic procedure of endometriosis did not significantly improve the sensitivity or specificity. CONCLUSIONS: There is no significant added value of routine MRI after dynamic TVUS for the preoperative staging of endometriosis.@en