Background: Clinical Laboratory Services (CLS) are essential in emergency care for diagnosis and treatment. However, misuse can result in false positives and increased costs. This study explored CLS utilization patterns in a tertiary academic Emergency Department (ED). Methods: A retrospective observational study analyzed data from 8,407 patients visiting the ED of a tertiary university hospital between January and September 2024. A total of 19,486 emergency visits and 47,951 laboratory test orders were reviewed to explore the relationship between test ordering patterns and utilization rates per patient visit. Results: The average number of test orders per patient was 5.7, with an average of 2.46 orders per visit. Female patients had more ED visits (52.8%) and test orders (53.54%) than males (47.2%; 46.46%). The differences in visits and test orders between genders across test categories were statistically significant (p<0.0001). The average test orders per visit were slightly higher for females (2.50) than males (2.42). Microbiology and biochemistry were the most ordered tests in both genders. Patients under 20 had the highest test orders per visit (2.74 for females, 2.79 for males), while the 40-60 group had the lowest. Significant variations in seasonal trends and laboratory test ordering categories were also observed across all age groups in both genders. Conclusions: Our study analyzed ED laboratory test ordering patterns, highlighting gender and age disparities, seasonal trends, and inefficiencies. Additional investigation needed to measure the specific effect of evidence-based protocols, physician training, and policy measures on patient outcomes at the level of each illness.

Keywords: Clinical laboratory testing; Pattern; Emergency; ICD-10