Low Clinical Value Pathology Tests in the Emergency Department: Audit of Urine Microbiology and Culture Use at a Large Regional Centre.

OBJECTIVE

To assess the ordering practices of urine Microscopy Culture and Sensitivity (MCS) tests in a regional NSW emergency department. Our goal was to determine practices and alignment with diagnostic guidelines to inform future development of targeted interventions to reduce unnecessary testing.

METHODS

Retrospective review of NSW Pathology data on all urine samples sent for MCS testing from the Emergency Department between January 1 and December 31 of 2023. Data were merged with patient clinical data and 500 cases randomly selected for manual audit. Data extracted included patient characteristics, symptoms, urine analysis (UA) results, MCS results, treatment and whether results changed patient management.

RESULTS

There were 7074 urine MCS requests, equating to 88 requests per 1000 ED presentations. In the audited sample of 500 cases, 22.4% yielded positive cultures, and 15% were mixed growth/contamination. Only 87% of patients (n = 433) had a UA before MCS. UA had a 93.2% (95% CI: 88.9-96.2) negative predictive value overall and 88.2% in asymptomatic patients. Nearly half (41.6%, n = 208) of patients were treated with antibiotics, 22.4% (n = 112) in the absence of a positive MCS. An estimated 27% of MCS tests could have been safely avoided based on the absence of clinical symptoms. When extrapolated to the whole sample, this could save approximately $39, 538 in pathology costs.

CONCLUSIONS

A significant proportion of urine MCS was ordered without a clear indication. Reinforcing guideline-based ordering and emphasizing UA screening could reduce unnecessary testing, decrease healthcare costs, and minimize potential harm from overtreatment.