Introduction

Training programs in ultrasound (particularly point of care ultrasound (POCUS)) are already well-established for postgraduate medical practitioners [1]. More recently, undergraduate medical programs are integrating ultrasound (US) into their curricula. The Ultrasound in Medical Education Portal lists over 200 medical schools on the AIUM (American Institute of Ultrasound Medicine) website as having a curriculum which includes an ultrasound component [2]. In 2014, the American Academy of Emergency Medicine issued a clinical practice statement declaring that ‘Ultrasound should be integrated into undergraduate medical education curricula’ [3]. The purpose of this study is to provide a guide for medical educators of the available evidence regarding how best to integrate ultrasound (e.g., correlating human anatomy with corresponding ultrasound images or sonoanatomy) and the possible learning opportunities associated with it (e.g., using it as a teaching tool to demonstrate blood flow or focusing on its clinical applications). We aimed to inform medical educators of the following:

  1. (i)

    the different categories of literature available on the topic of undergraduate ultrasound

  2. (ii)

    findings of importance from researchers in this field

  3. (iii)

    future directions for ultrasound in undergraduate medical education

Given the heterogeneous literature that has emerged in this field, a scoping review was conducted. Scoping reviews differ from systematic reviews in that they have a broader focus and are often employed as a means of defining the parameters of the literature on a given subject [4].

Methods

Data Sources and Searches

A search of electronic databases (Pubmed, EMBASE, CINAHL, Medline, PyscINFO) was conducted for educational studies published between January 1980 and August 2016 that either directly taught medical students the use of ultrasound or that reviewed an ultrasound program for medical students. Search terms were combined as per Table 1. Hand searched articles, including articles we found while examining reference lists from identified primary papers, were also examined for inclusion.

Table 1 Literature search terms
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Study Selection

The process for article screening is outlined in the PRISMA flow (Fig. 1). Only full-length articles published in English were considered for inclusion. Duplicate articles within or between databases were excluded with the help of the referencing software Endnote (version X7.4). The remaining full-text articles were screened independently for inclusion by two reviewers (CN, JB). Discrepancies between reviewers were resolved through consensus. Inclusion criteria were prospective or retrospective studies, observational or intervention studies and studies describing how medical students learn to use ultrasound. Articles were excluded as per the PRISMA flow (Fig. 1; for citation references, see Appendix A). Studies that met the inclusion criteria were reviewed by two reviewers (CN, JB) for thematic commonalities. Once categories were formulated the major findings from these categories were discerned and discussed.

Fig. 1
figure 1

PRISMA flow of literature search

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Results

The literature search yielded 593 articles, of which 128 were considered eligible for inclusion.

The categories that emerged were as follows: papers that described or evaluated an ultrasound curriculum and papers that surveyed those involved in the development and evaluation of these curricula; those that employed ultrasound as a means of teaching another topic in the curriculum (e.g., anatomy, physiology, physical examination, invasive procedures); articles that examined the learning curve for undergraduate ultrasound and articles that described the use of adjunctive methods or technology in the teaching of ultrasound to medical students, including those which used peer mentoring. Where papers featured elements of more than one category, they were classified with respect to the category that best fitted the primary focus of the paper. Tables (1, 2, 3, 4 and 5) are presented for each category.

Table 2 Curriculum papers—20 papers
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Table 3 Learning category—67 papers
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Table 4 Learning Curve—seven papers
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Table 5 Adjunct category—34 papers
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Curriculum

Papers categorised in the curriculum category either described a fully-formed ultrasound curriculum or described an ultrasound teaching intervention that spanned more than a single educational theme or goal. We also included in this section papers that surveyed ultrasound educators with respect to ultrasound implementation or assessment in medical schools.

Learning Category—Incorporation of Ultrasound into Teaching of Another Curriculum Topic

Sixty-seven papers were categorised as incorporating US into teaching a particular part of the curriculum. Some authors have described POCUS as the ‘new stethoscope’ [119] and the majority of the papers which focus on a curriculum topic have taught ultrasound in the context of physical examination (31 papers). Fifteen papers focus on the teaching of sonoanatomy while smaller numbers focus on the topics of physiology and invasive procedures.

The Learning Curve for Undergraduate Ultrasound Education

The learning curve category includes papers that either inform educators regarding factors that enhance or limit student learning ultrasound, or formally examine the learning curve for the acquisition of ultrasound skills.

Adjunctive Technologies and Teaching Methods in Undergraduate Ultrasound Education

The adjunct category comprises papers that describe or evaluate adjunctive technologies and teaching methodologies in the teaching of ultrasound to undergraduates.

Discussion

Our review of the current literature on the integration of US into medical school curricula found that the published research is focused on the following four areas:

  1. (1)

    Descriptions of various fully and partially integrated ultrasound curricula where ultrasound has been integrated into two or more years of the medical school curriculum. A small number of these programs include objective evaluation. In addition, surveys of program administrators are available, giving insights into the process of successfully integrating ultrasound into an undergraduate medical curriculum.

  2. (2)

    Descriptions of the incorporation of ultrasound into one topic in the curriculum (i.e., anatomy, physiology, physical examination, invasive procedures). Some authors included an evaluation of these educational interventions.

  3. (3)

    Descriptions of the learning curve of ultrasound education

  4. (4)

    Descriptions and evaluations of using adjuncts or peer mentoring to teach US.

Six take home messages from this scoping review:

  1. 1.

    Integrate Ultrasound into the Undergraduate Medical Curriculum—‘Just Do It’

The major difference in the papers categorised to category 1 or 2 is one of scale. Incorporation of ultrasound into an entire curriculum is a much larger undertaking than standalone additions to parts of a curriculum. The latter can be achieved in lower-resourced settings but the former, while resource intensive, leads to a more robust program. Twenty-one percent of the papers in this review (27 of 128 publications) have involved three authors from three different institutions that have integrated ultrasound teaching within each year of their medical school curriculum (DP Bahner, JC Fox and RA Hoppmann). Full integration has allowed for the development of such programs over time, with incorporation of feedback and continued improvement [10, 11].

The investment of these medical schools in ultrasound is being rewarded by increased student interest, with some evidence emerging that medical students are choosing programs based on their investment in ultrasound [11] leading to our first take home message which is ‘Integrate ultrasound into your undergraduate medical curriculum’. If possible, invest in a fully integrated program. Such programs do require a significant initial investment in terms of faculty, equipment and administration; however, if your medical school does not have the resources for this initial investment, the evidence is there to support integrating ultrasound into one topic in the curriculum such as anatomy and building out from this as resources allow. A recurring theme in the papers that employed ultrasound to teach anatomy was the use of ultrasound to teach ‘living anatomy’ [25,26,27].

The majority of papers in this scoping review (67/128) described the use of ultrasound as a tool to enhance the teaching of another topic or a clinical skill.

  1. 2.

    Evaluate your program objectively and incorporate an image management system.

Objective measures of ultrasound performance have been developed but have yet to be validated in the undergraduate population. The majority of papers that we reviewed were satisfied to rely on students’ subjective ratings of their own learning experiences. The limitations of such data are clear: students may rate a course as favourable even where their knowledge gains were modest and no reliable comparison is possible between the effectiveness of the various educational interventions described. Students tend to overestimate their performance, but a significant amount of knowledge can be retained at 8 months in a well-structured program [8].

One way of assessing students is to use the national sonographer standard [5]; however, this standard will vary between countries. Although medical students can reach national sonographer standards with a structured integrated approach [5], the majority of student scores tended to be akin to ‘a borderline level of competency’. This underscores the need for a structured approach to undergraduate ultrasound education which incorporates a robust image review and management system [15]. Many programs up to this point have been evaluated using various pre- and post-test questionnaires, MCQ exams and checklists; however, validated tools are emerging [21, 22].

In 2013, Tolsgaard et al. achieved international consensus across multiple specialties on a generic ultrasound rating scale using a Delphi technique [133]. In 2014, Tolsgaard et al. published their assessment of 30 ultrasound users. They used their OSAUS scale (Objective Structured Assessment of Ultrasound Skills) to successfully differentiate novice, intermediate and experienced obstetric and gynaecology physician ultrasound users [134]. In 2015, Todsen et al. replicated this work for point of care ultrasound in a group of 24 physician participants [135]. The OSAUS has yet to be validated in the undergraduate population. Our research group believes this is the next step to advance the field of undergraduate ultrasound education.

  1. 3.

    Involve the right people—include emergency physicians, radiologists, sonographers and clinicians who use ultrasound on a daily basis. Consider the value of peer-teaching.

Currently, the majority of programs are led by emergency medicine faculty but there is a growing engagement of radiologists in undergraduate ultrasound teaching [23]. Given the already high demands on faculty for teaching time, institutions should consider enlisting the help of ultrasound professionals such as sonographers, or peer teachers. Near peer teaching offers an opportunity for advanced students to push their learning horizons further, while also relieving an oft-cited limitation in ultrasound program construction—the availability of qualified faculty that can meet a large teaching commitment [126].

  1. 4.

    Ultrasound simulators and phantoms are versatile adjuncts that allow for ultrasound teaching in the absence of patients or cadavers

Some of the most common teaching adjuncts employed in the ultrasound literature were ultrasound simulators and phantoms. The evidence supports the use of simulators as well as several novel low-cost teaching tools for the less well-resourced educator. Ultrasound can also complement cadaver-based teaching, allowing invasive interventional skills (central line placement [85, 86], pericardiocentesis [87], surgical biopsy [88]) to be taught on realistic anatomy without compromising patient safety. Where cadavers are not available, ultrasound simulators and phantoms can fulfil a similar role.

  1. 5.

    Use small group teaching and spend some time on knobology and physics—this accounts for a significant cognitive load for novices

Ultrasound is operator-dependent; however, students can learn quickly [8], particularly with small-group teaching [93]. Jamnickzky et al. [97] highlighted the cognitive load imposed by ultrasound ‘knobology’ on novice learners, a finding which serves as a warning to educators that teaching the basics of the technology cannot be sacrificed, even in a time-limited setting.

  1. 6.

    Harness student enthusiasm

One constant among the heterogeneous literature reviewed here was in students’ responses to ultrasound teaching. In every paper in which students’ subjective assessment of ultrasound incorporation into the curriculum was sought, it was very positive. The benefits of active student engagement and leadership have also been demonstrated in student-led ultrasound interest groups [102], where students interested in ultrasound have the opportunity to organise educational events and demonstrate autonomy in their learning. Medical students respond positively to US and, after receiving undergraduate ultrasound instruction, are more likely to use US in their postgraduate practice [24].

Conclusions and Future Directions

Integration of ultrasound into the medical school curriculum is feasible and beneficial to medical students. Those programs with greater integration deliver a more robust ultrasound education. The quality of an ultrasound curriculum is dependent on involving a wide range of ultrasound practitioners, from radiology faculty to peer teaching. Ingenuity in teaching technologies and strategies, including the use of low-cost simulators and near peer teaching, has provided an example of how ultrasound can be taught, even in less well-resourced medical schools.

The following gaps exist: (1) Long-term follow-up studies demonstrating that learners improve with existing teaching methods and (2) the use of validated tools (such as OSAUS) to assess learners and programs.

Ultrasound education researchers should look to the established medical education literature to design follow-up studies which can demonstrate that structured training programs improve the ultrasound skills of students. The authors agree with Hoppmann et al.’s [11] call for ‘an international consensus conference on US education to help define the essential elements of US education globally to ensure US is taught and ultimately practiced to its full potential’.

Limitations of This Paper

Limitations of space precluded a comprehensive analysis of each paper uncovered in our search. For this same reason, papers were generally only reported in the category that best fitted their primary focus. For example, a teaching intervention for physical examination that had, as a component, an e-learning module or a simulator was categorised under the physical examination heading and not in terms of the adjunctive technologies employed.