How Pre-Analytical Factors Affect Blood Culture Diagnostic Accuracy in Adult Inpatients: A Cross-Sectional Analysis

Background and Purpose: Blood culture (BC) remains the gold standard for detecting bloodstream infections. Given the typically low microbial load in adult bacteremia, both the volume of blood sampled and proper collection techniques are essential for diagnostic accuracy. This study aimed to evaluate BC collection practices in adult patients, focusing on blood volume adequacy, departmental variation, and the influence of pre-analytical factors on culture yield.Material and Methods: This retrospective study included all aerobic and anaerobic BC bottles submitted from adult patients to the Microbiology Laboratory of XXX University Faculty of Medicine between January 10 and April 30, 2022. Blood volume per bottle was visually measured post-incubation. Demographic and clinical data were extracted from hospital records.Results: A total of 4695 BC bottles representing 1463 episodes from 712 adult patients were analyzed. Only 47% of episodes met the recommended standard of at least two sets per episode. About one-fourth of bottles were optimally filled, with overfilling more prevalent than underfilling. Overfilling was paradoxically associated with lower positivity rates. Patients with malignancy had significantly higher blood volumes, while those with neuropsychiatric conditions or recent surgery had lower volumes. Blood volumes were substantially lower in the ICU and emergency departments. Central venous catheter use was associated with higher but not necessarily optimal blood volumes.Conclusion: Suboptimal adherence to BC sampling standards, particularly in blood volume and set number, persists across clinical settings. Interventions targeting pre-analytical errors and departmental differences may improve diagnostic yield in suspected bloodstream infections.