Impact on Diagnostic Accuracy of a Specific Clinical Ultrasound Practical Teaching

Background Critical care and emergency medicine are both specialties covering all types of pathologies concerning multiple etiologies and systems. Clinical UltraSound (CUS) curricula concerning those specialties are accordingly covering a wide range of ultrasound improved clinical examination. Recently, a questionnaire sent to American medical schools, reporting 84% response rate, enlightened that 55% of the clinical ultrasound course directors are emergency physicians. This supports the great implication of emergency medicine in CUS development.

In 2015, the International Federation for Emergency Medicine (IFEM) Point of Care UltraSound (PoCUS) published an evidence-based consensus document for CUS curriculum based on national and international guidelines. Previously, the Council of Emergency Medicine Residency Director-Academy of Emergency Ultrasound (CORD-AEUS) consensus established guidelines to organize CUS training and assess resident competencies. To actual knowledge, although CUS training programs around the globe support the use of specific training to achieve CUS introduction in the emergency departments endorsing its use, there are still significant variations among proposed curricula. The training requirements are mostly described for core-ultrasound. Generally, core-ultrasound curricula encompass the skill acquisition of extended-Focused Assessment Sonography for Trauma (e-FAST), Aortic Aneurysm Assessment (AAA), basic cardiac and lung ultrasound and basic procedural ultrasound. Some include biliary and urinary tract assessment whereas others consider biliary and urinary tract assessment part of advanced CUS teaching. Most other specialties however focus their ultrasound teaching on the field of interest. For instance, urologists learn how to perform an ultrasound assessment of the urinary tract or the prostate whereas gastroenterologists focus their ultrasound ability on bowel and biliary.

Currently, based on emergency medicine requirements, the CUS training consist of an initial introduction followed by gaining experience throughout image acquisition, image interpretation and clinical integration and finally achieving competency. Different approaches and methods of teaching are available and often a combination of those is recommended in available curricula description. Many recommend reporting pathological CUS cases among ultrasound images compeeled in a logbook, either a certain amount (20% to 50%), either generically, in their core-ultrasound competency requirements. Although its benefit for emergency medicine clinical practice is substantial and evidence based, the introduction of CUS in emergency physicians' practice is evidently time consuming possibly due to theoretical and practical sessions requirements and assessments as well as bedside supervision. Several curricula recently included CUS to emergency medicine requirements program and more broadly to medical students' courses. This brings to a large number the need for CUS bedside teaching combined with other sources of competence achievement.

In an emergency clinical setting, the use of CUS for hepatobiliary assessment is mostly centered on inflammation and obstruction. Cholecystitis is known to be, from 95% to 99% of cases secondary to gallstones. Gallstones are accessible to CUS and, included in the clinical context, can strengthen the suspicion of cholecystitis. In a systematic review performed in 2011, the pooled estimates for sensitivity and specificity were 89.8% (95% confidence interval (CI) 86.4% to 92.5%) and 88.0% (95% CI 83.7% to 91.4%), respectively for gallstones detection using EUS. This is consistent with this finding being valuable for clinical practice. Although some studies supported the number to achieve agreement with expert for gallbladder assessment to be 25 to 50, a prospective study including 1837 patients from 1999 to 2006, reported the learning curve of emergency physicians for the evaluation of gallbladder is poorly influenced by the number of bedside examinations. Those considerations suggest other sources of competency achievement should be evaluated rather than the number of examinations itself.

Classically, initial CUS introduction uses short lectures combined with demonstration, "hands-on" skill teaching, simulation sessions, discussions, web-based learning and practical scanning on volunteers, models and patients. Occasionally, pathological models are difficult to find and bedside teaching, apart from clinical shift, is exclusively possible on volunteers presenting a normal pattern. This enlightens the need for studies evaluating the CUS training pathway using exclusively healthy volunteers compared to the use of pathological findings during practical sessions. This is strengthen by the introduction of CUS courses among medical schools. Indeed, unlike residents or physicians, medical students don't have as much possibility to access practical CUS training on patients presenting pathological patterns.

The following study is meant to give insights about the CUS skills acquisition to accurately diagnose gallstones using exclusively training on healthy volunteers after a standardized web based theoretical teaching about pathological and non-pathological gallbladder CUS. This could support the use of only healthy volunteers during practical sessions. The teaching of pathological images recognition could exclusively be done throughout theoretical sessions. Although this would neither avoid the need for enhancing competencies bedside, neither avoid continuous logging activity and regular CUS continuing medical education, this could secondary help CUS teaching by reducing the need for bedside supervision during clinical shifts. Indeed, to knowledge, bedside supervision is difficult to achieve in some emergency departments and CUS fellows have trouble to properly fill out a " logbook ". Organizing CUS teaching around normal pattern recognition associated to a theoretical course presenting pathological findings could lead to change CUS fellows' assessment. Those could be evaluated theoretically using pathological ultrasound images or loops and could be evaluated practically on healthy volunteers. This would avoid compelling a " logbook " which can arise some ethical discussion about patient consent and use of images even if the latter are classically anonymized.

According to scope literature review, no randomized control study has been published establishing the skills acquisition for gallstones findings. This study being a pilot one, it will allow to precise the feasibility of a proper randomized control trial and to evaluate sample size. This study could also be the starting point of randomized control trials concerning the teaching of other pathological findings such as free fluid, aortic aneurism, cardiac assessment, hydronephrosis.

The Main objectives to evaluate if CUS skills to diagnose gallstones can be acquired by 5th year medical students naïve to CUS use exclusively throughout practical sessions on healthy volunteers after a standardized theoretical teaching using a web-based passive video learning.

The Trial design is a pilot double-blind randomized control trial. 20 participants are randomly assigned to CG or IG using pre-defined blocks of 10 participants per group. Consolidation of knowledge and skills' acquisition for gallbladder evaluation using CUS take place during 3 teaching sessions (day 0-10-30) given by CUS instructors on volunteers. Evaluation of diagnostic accuracy (day 60) is performed at the end of the 2 months teaching period by two blinded examiners. The teaching is performed according to an expanding time interval as supported by a recent review.

Study members

--> Instructors Instructors are selected from the population of experts in CUS of the gallbladder in Belgium ; they are invited to participate via e-mail.

Each instructor receives a financial compensation for participating to the study.

Instructors are not blinded to participants' allocation. Instructors sign a "non-disclosure agreement" meaning they cannot give information to a third party during the entire duration of the study.

--> Volunteers Healthy volunteers are invited to participate by e-mail. Volunteers are selected using a web-based questionnaire asking for characteristics (age, sex, BMI).

Volunteers presenting a pathological gallbladder status (gallstones, sludge), are invited to participate throughout the consultation of surgery of the "Cliniques Universitaires Saint-Luc", before an elective surgery is planned.

Volunteers are paired for age (+/- 5 years) and BMI (+/- 1) between groups to avoid selection bias.

Volunteers are eligible if:

• Between 18 and 70 years old
• Signed consent for participation and "non-disclosure agreement" 1 obtained
• Underwent a formal ultrasound previous to the study day in order to confirm gallbladder status (gallstones or sludge yes/no), performed by a CUS expert independent from the study
• Do not have persistent abdominal pain or cholecystitis symptoms Volunteers are committed to "non-disclosure agreement" about their gallbladder status during their participation to the study, except in case of medical consultation for personal matter.
• Examiners Two examiners, blinded to participant allocation, evaluate practical skills of participants for gallbladder assessment using CUS on day 60.

Examiners are international experts in CUS coming from United Kingdom.