Condition-Specific Protocols Used in the Emergency Department Observation Unit: A Scoping Review

<h2>Abstract</h2><h3>Background</h3> Emergency Department Observation Units (EDOUs) provide time-limited care for patients not clearly requiring inpatient admission. Despite widespread adoption, evidence describing condition-specific EDOU protocols remains fragmented. We conducted a scoping review to map the clinical conditions, characteristics, and outcomes of published EDOU protocols. <h3>Methods</h3> This review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) guidelines. PubMed was searched for articles published between January 1, 2000, and June 1, 2025. Eligible publications reported condition-specific EDOU clinical care pathways for adult populations. Articles were screened and extracted by 2 reviewers in Covidence. Findings were summarized using descriptive statistics and Poisson regression modeling. <h3>Results</h3> Of 6,741 publications identified, 239 met the inclusion criteria. Publications appeared in 93 journals and increased annually by 4%. Most studies were observational (72%) and conducted at academic centers (78%). Most protocols addressed diagnostic (45%) or diagnostic-therapeutic (28%) pathways, although there was a recent increasing trend in therapeutic pathways. Cardiology, particularly chest pain management, represented the predominant clinical focus, followed by infectious disease. Protocols describing geriatric care and viral illness management showed significant annual increases of 16% and 19%, respectively. Frequently reported outcomes included disposition rates, mortality, and return emergency department visits, whereas patient- and provider-centered outcomes were less commonly assessed. <h3>Conclusions</h3> The EDOU protocol literature has expanded substantially over the past 25 years but remains concentrated in a limited number of clinical domains. Greater emphasis on underrepresented conditions and outcome measures may help guide the next generation of evidence-based EDOU protocols.