Direct Mass Spectrometry Differentiation of Ectopic and Eutopic Endometrium in Patients with Endometriosis

Study Objective: To introduce a method for the rapid assessment of endometriotic tissues using direct mass spectrometry (MS)-based lipidomics. Design: A prospective observational cohort study (Canadian Task Force classification II2). Setting: Department of Operative Gynecology of the Research Centre for Obstetrics, Gynecology and Perinatology. Patients: Fifty patients with ovarian cysts and peritoneal endometriosis who underwent laparoscopic surgery between 2014 and 2016. Intervention: Differences in mass spectrometric profiles of ectopic endometria (endometriosis) and eutopic endometria were analyzed for each patient in combination with morphohistologic evaluation. The lipidomic approach was applied using a direct high-resolution MS method. Measurements and Main Results: Of 148 metabolites, 15 showed significant differences between endometriotic tissue and a healthy endometrium of the same patient, considered as a control in this study. The main lipids prevalent in endometriotic tissues were phosphoethanolamine (PE O-20: 0), sphingomyelin (SM 34: 1), diglycerides (DG 44: 9), phosphatidylcholines (PC 32: 1, PC O-36: 3, PC 38: 7, PC 38: 6, PC 40: 8, PC 40: 7, PC 40: 6, PC 40: 9, and PC O-42: 1), and triglycerides (TG 41: 2, TG 49: 4, and TG 52: 3). Using partial least squares discriminant analysis models, MS showed that the lipidomic profile of endometriotic tissue (peritoneal endometriosis and ovarian endometriomas) was clearly separated from the eutopic endometrium, indicating tissue-type differentiation. Conclusion: Our results suggest that direct MS may play an important role for endometriotic tissue identification. Such an approach has potential usefulness for real-time tissue determination and differentiation during surgical treatment. Lipids of 3 important classes, sphingolipids, phospholipids, and the fatty acids (di-and triglycerides), were identified. Validation is required to determine whether these lipids can be used to discriminate between patients with endometriosis and those with other gynecologic diseases. (C) 2017 AAGL. All rights reserved.