Mapping Methodological and Disease-Specific Gaps in Endometriosis Biomarker Research: A Scoping Review

Endometriosis is a chronic, inflammatory gynecologic disease affecting approximately 10% of individuals assigned female at birth worldwide and is associated with substantial morbidity, reduced quality of life, and significant diagnostic delay. Despite decades of investigation, no non-invasive biomarker or biomarker panel has yet achieved sufficient validation for routine clinical implementation. While numerous primary studies and systematic reviews have evaluated candidate biomarkers across diverse biofluids and molecular classes, limitations in study design, disease characterization, reporting transparency, and validation practices have been repeatedly acknowledged in a fragmented manner. To date, to our knowledge, no structured synthesis has systematically mapped how methodological choices, engagement with biological complexity, and reporting practices vary across stages of biomarker development or across time. The purpose of this scoping review is to generate a structured map of endometriosis biomarker research, with a focus on identifying recurrent methodological and disease-specific gaps that may contribute to heterogeneity, limited reproducibility, and translational bottlenecks. Rather than evaluating or ranking biomarkers based on diagnostic performance metrics, this review examines how evidence has been generated and advanced across the biomarker development pipeline, from exploratory discovery through validation and clinical evaluation phases. Specifically, this review will: (1) Summarize methodological and reporting practices that influence reproducibility and interpretability; (2) Assess the extent to which studies incorporate endometriosis-specific biological complexity; (3) Map the distribution of studies across stages of biomarker development, from discovery to validation; and (4) Evaluate temporal trends to understand how the field has evolved over time. Data will be synthesized using a structured mapping framework combining narrative summaries, descriptive tabulation, and predefined visual outputs to illustrate patterns of evidentiary concentration, methodological practices, and areas of translational attrition. The objective is to benchmark the current state of the field and identify systemic barriers to translation. The expected outcome of this project is a comprehensive, stage-aware map that clarifies how methodological practices and disease framing influence the translational trajectory of endometriosis biomarker research. By systematically identifying structural gaps and patterns of heterogeneity, this review aims to inform the design of future biomarker studies, support more biologically contextualized and reproducible research practices, and provide guidance to clinicians, researchers, and funding bodies seeking to advance clinically meaningful diagnostic tools in endometriosis.