Correlation of OSCE performance and point-of-care ultrasound scan numbers among a cohort of emergency medicine residents

BACKGROUND: Point-of-care ultrasound (POCUS) is an important clinical tool for a growing number of medical specialties. The current American College of Emergency Physicians (ACEP) Ultrasound Guidelines recommend that trainees perform 150–300 ultrasound scans as part of POCUS training. We sought to assess the relationship between ultrasound scan numbers and performance on an ultrasound-focused observed structured clinical examination (OSCE). METHODS: This was a cross-sectional cohort study in which the number of ultrasound scans residents had previously performed were obtained from a prospective database and compared with their total score on an ultrasound OSCE. Ultrasound fellowship trained emergency physicians administered a previously published OSCE that consisted of standardized questions testing image acquisition and interpretation, ultrasound machine mechanics, patient positioning, and troubleshooting. Residents were observed while performing core applications including aorta, biliary, cardiac, deep vein thrombosis, Focused Assessment with Sonography in Trauma (FAST), pelvic, and thoracic ultrasound imaging. RESULTS: Twenty-nine postgraduate year (PGY)-3 and PGY-4 emergency medicine (EM) residents participated in the OSCE. The median OSCE score was 354 [interquartile range (IQR) 343–361] out of a total possible score of 370. Trainees had previously performed a median of 341 [IQR 289–409] total scans. Residents with more than 300 ultrasound scans had a median OSCE score of 355 [IQR 351–360], which was slightly higher than the median OSCE score of 342 [IQR 326–361] in the group with less than 300 total scans (p = 0.04). Overall, a LOWESS curve demonstrated a positive association between scan numbers and OSCE scores with graphical review of the data suggesting a plateau effect. CONCLUSION: The results of this small single residency program study suggest a pattern of improvement in OSCE performance as scan numbers increased, with the appearance of a plateau effect around 300 scans. Further investigation of this correlation in diverse practice environments and within individual ultrasound modalities will be necessary to create generalizable recommendations for scan requirements as part of overall POCUS proficiency assessment.