{"paper_id":"ab038d29-631d-4088-9853-43dd17e88e72","body_text":"Feb 10, 2026\nFresh versus frozen embryo transfer in endometriosis-Systematic review\nDOI\nhttps://dx.doi.org/10.17504/protocols.io.6qpvry7z3gmk/v1\nAlexandraIoannidou,NikolaosMachairiotis\nNational Kapodistrian University of Athens\nAlexandra Ioannidou\nNational Kapodistrian University of Athens\nCreate & collaborate more with a free account\nEdit and publish protocols, collaborate in communities, share insights through comments, and\ntrack progress with run records.\nCreate free account\n1 1\n1\nDOI: https://dx.doi.org/10.17504/protocols.io.6qpvry7z3gmk/v1\nProtocolCitation: Alexandra Ioannidou, Nikolaos Machairiotis2026. Fresh versus frozen embryo transfer in endometriosis-\nSystematic review.protocols.iohttps://dx.doi.org/10.17504/protocols.io.6qpvry7z3gmk/v1\nLicense:This is an open accessprotocoldistributed under the terms of theCreative Commons Attribution License,  which\npermits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited\nProtocol status:Working\nWe use this protocol and it's working\nCreated:February 10, 2026\nprotocols.io | https://dx.doi.org/10.17504/protocols.io.6qpvry7z3gmk/v1 February 9, 2026 1/3\n\nLast Modified:February 10, 2026\nProtocolInteger ID:242934\nKeywords: endometriosis, fresh versus frozen embryo transfer, fertility outcomes, fresh versus frozen embryo transfer, fresh\nembryo transfer, endometriosi, controlled endometrial environment, frozen embryo transfer, women with endometriosi, embryo\ntransfer, concerns that the endometrial environment, endometrial environment, optimal embryo transfer strategy, endometrial\nreceptivity, endometrium, widespread use of ivf, same cycle as ovarian stimulation, ovarian hyperstimulation, controlled ovarian\nhyperstimulation, adverse effects of ovarian stimulation, ovarian stimulation, infertility, reproductive outcome, fertility outcome,\nreproductive technology, hormonal deregulation at the time, hormonal deregulation, embryo, ivf, comparable success rate for\nconception, implantation, suboptimal for implantation, hormone level, supraphysiological hormone level, conception\nAbstract\nBackground: Endometriosis is an estrogen-dependent inflammatory disorder that is typically related to infertility,\nfor which assisted reproductive technologies are needed. Fresh embryo transfer can result in hormone levels that\nare supraphysiological, and this can have an impact on receptivity. Alternatively, frozen embryo transfer can be\nperformed and completed in a separate cycle, but it is unknown if there is a comparable success rate for\nconception. Methods: The search in PubMed, Europe PMC, and Google Scholar will be done comprehensively\nusing the keywords \"endometriosis,\" \"fresh versus frozen embryo transfer,\" and \"fertility outcomes\" for articles\npublished from 2010 until January 2026. Only those studies will be included that provide information specifically\non endometriosis-patients. Data will be extracted by two authors using predefined criteria. Despite widespread\nuse of IVF in this population, optimal embryo transfer strategies remain controversial. Traditionally, embryos have\nbeen transferred in the same cycle as ovarian stimulation (fresh embryo transfer). However, controlled ovarian\nhyperstimulation induces supraphysiological hormone levels, which may adversely affect endometrial receptivity.\nThese pathophysiological features raise concerns that the endometrial environment during fresh cycles may be\nsuboptimal for implantation in this subgroup. Frozen embryo transfer FET) has been proposed as an alternative\napproach, where embryo transfer is performed in a subsequent cycle in a more physiologic or controlled\nendometrial environment. For women with endometriosis, FET may theoretically reduce the adverse effects of\novarian stimulation on the endometrium and inflammatory/hormonal deregulation at the time of implantation.\nExtracting data of existing studies is challenged by heterogeneity in disease severity, stimulation protocols, and\nstudy design. Given the lack of consensus and the growing clinical use of FET, a systematic synthesis of the\navailable evidence is justified. Our systematic review aims to compare reproductive outcomes following fresh\nversus frozen embryo transfer in women with endometriosis.\nGuidelines\nThis systematic review will be carried out strictly according to the guidance by the PRISMA Statement.\nprotocols.io | https://dx.doi.org/10.17504/protocols.io.6qpvry7z3gmk/v1 February 9, 2026 2/3\n\nMethods\n1 A systematic search of three major databases—PubMed, Europe PMC, and Google\nScholar—will be performed with the keywords \"endometriosis, fresh versus frozen\nembryo transfer, fertility outcomes\". All available articles will be considered for this study\nfrom 2010 until January 2026.\n2 Articles have to be full-length research papers written in English, whereas abstracts\npresented at scientific meetings, case reports and review articles will be excluded. In\naddition, only those studies will be included that provide information specifically on\npatients with endometriosis. Rest of patient-groups will be excluded. The quality and\npotential risk of bias for these studies will be assessed using the ROBINSI tool.\n3 Specific data will be extracted from each publication in duplicate, including publication\ndate, authorship, studied population, methodologies employed, criteria for inclusion or\nexclusion I/E, sample type, and primary outcome measures.\nResults\n4 Results will be presented in a standardized fashion and the publication and author data,\ndemographics, metrics, and key findings of the included studies will be tabulated to\noptimize readability.\nDiscussion\n5 A critical appraisal of the included studies will be undertaken.\nConclusion\n6 In this section, we will recapitulate the key findings of our research.\nprotocols.io | https://dx.doi.org/10.17504/protocols.io.6qpvry7z3gmk/v1 February 9, 2026 3/3","source_license":"CC0","license_restricted":false}