Despite the proven benefits of EU, it is only used in a minority of EDs [17–19]. Since formal ultrasound often requires 30 min or more to perform, many EPs may have the perception that EU is too time-consuming to incorporate into their clinical practice. Contrary to this perception, this study has shown that EU exams only require a mean of 2 min, 17 s to perform. Therefore, the authors believe that EU exam duration should not represent an impediment to the incorporation of EU into emergency medical practice. Furthermore, one does not need to be an expert to perform EU efficiently. The EPs with the most experience in our group performed EU exams only 19 s faster than the rest of the EPs. This is a clinically and statistically insignificant difference. Despite the brevity of this exam, determinate results were obtained in 57 of 66 EU cases.
The duration of positive, negative and indeterminate EU exams did not differ significantly. As well, there was no statistically significant difference in the duration of the various EU exam types. However, the subgroups were small. There was a trend towards indeterminate scans requiring more time to complete. As well, there was a trend towards cardiac and transabdominal pelvic scans being briefer, and transvaginal being a longer scan. Larger subgroups would be required to make a firm conclusion.
This is the first study to accurately measure the time required by physicians certified in EU to perform EU across all primary indications. Only one prior study has previously measured EU exam duration for all of the primary indications [23]. All other studies have focused on trauma [24–27, 29–34] or deep venous thrombosis (DVT) [22, 28]. Only three studies have included EU exams performed only by non-radiologist staff physicians and not trainees [22, 26, 34].
Prior studies [22–34] have reported a wide range of EU durations [22–34]. Only three studies have reported an EU duration in excess of 5 min [23, 27, 28]. Blaivas [23] reported that residents required a mean of 9 min, 53 s to perform EU. Healey reported that a comprehensive trauma scan required a mean of 10.1 min to perform. However, the scan was performed by an ultrasound technician and interpreted by a trauma surgeon. Jang reported that residents with limited training required a mean of 11.7 min to perform a DVT scan. In contrast, Blaivas [22] reported that a DVT scan performed by physicians with significant experience required a median of only 3 min, 28 s.
Four other studies have reported EU exam durations of less than 3 min [24, 25, 31, 34]. Only the trauma scan was the subject of these studies. One of these studies [25] found that EU duration reached a plateau of just over 2 min once the physicians completed 50–75 exams. The reliability of EU duration measurement has varied in previous studies. Only two studies used a stopwatch to time the EU exam [22, 23]. In three studies [24, 25, 34], all from the same centre, the duration was estimated using the duration of the videocassette recording of the scan. Self-reported estimates were used in four studies [28, 30, 32, 33]. Four studies did not report their method of measurement [26, 27, 29, 31].
Limitations and future questions
Several tasks associated with EU were not included in EU duration measurement. The time required to bring the machine to the patient bedside was not included in the duration. In our ED, ancillary personnel usually perform this task. Machine cleanup typically only requires a few seconds to perform. A more extensive cleaning of the endocavitary probe is performed by ancillary personnel. Documentation is usually limited to a written note in the chart and only takes a few seconds. In other jurisdictions, documentation requirements may be more extensive and time-consuming. The standard views performed for the primary indications may be fewer in Canada than in other countries and may limit the generalizability of these results.
It is possible that the physicians altered how they performed bedside ultrasound when being timed (i.e. Hawthorne bias). Individual physicians may have performed scans more quickly or slowly than usual when being timed. Physicians could not be blinded to the timing of their scans. Lastly, funding was sufficient to hire only one RA. It is possible that a second RA would have obtained different scan durations.
We did not measure the duration of EU exams performed for indications other than the primary indications. The duration of other EU exams (gallstones, hydronephrosis, etc.) could be the subject of a future study. As EU continues to disseminate throughout emergency medicine, more EU exams (primary and advanced applications) will be performed. Although individual EU exams may be brief, the impact of EU growth on EP staffing will need to be assessed.
