Do vaginal swabs alter empirical clinical management in obstetrics and gynaecology: A retrospective case-series and activity-based costing of the vaginal swab.

Background: Vaginal swab microbiological testing is commonly performed as routine clinical management for various obstetric and gynaecological presentations. The clinical utility and cost-effectiveness of vaginal swab microscopy, culture and susceptibilities (MCS) in altering empirical management is ill-defined.

Aims: To describe the clinical use of vaginal swabs in a tertiary women's hospital emergency department (ED), measure the impact of vaginal swabs on altering empirical clinical management, and to determine the economic cost of vaginal swab MCS.

Materials and methods: Retrospective case-series of vaginal swabs collected at a single, tertiary women's ED between January 2021 and July 2021. Symptomatology, clinical diagnosis, test results, and pre-swab and post-swab clinical management were determined upon medical record review. Economic costs of vaginal swab MCS were retrospectively determined via internal accounting records, permitting unit-level activity-based costing.

Results: A total of 660 vaginal swabs from 584 clinical episodes were included. Vulvovaginitis was the most common indication for swab collection (34.5%, 167 samples). Altered empirical management was observed in 9.8% of all swabs (95% CI 7.4-12.2%), with marked variability between clinical indications. Antimicrobial initiation was the most common alteration in management (8.9%, 95% CI 8.7-9.1%). The estimated cost of vaginal swab MCS was $29.71 AUD; labour, consumables and disposal costs accounted for 69.3, 29.8 and 0.9%, respectively.

Conclusions: The impact of vaginal swab MCS on empirical clinical management is context-specific and variable. The majority of swabs performed do not impact upon empirical management. Antimicrobial initiation is appreciably more common than antimicrobial cessation with vaginal swab results.