Ultrasonography (USG) has the advantages of non-invasiveness, no risk of radiation exposure, and simplicity of providing real-time images.¹ Recently, USG has become widespread in clinical medicine and has changed the clinician’s approach to many diseases.^2-5 The interest of clinicians is increasing as the ease of access to ultrasound devices and abdominal ultrasonography is also widely performed by non-radiologists, e.g., primary care physicians, to evaluate chronic liver disease and disease of gall bladder.⁶ In line with this trend of clinical practice, abdominal ultrasound is included in the mandatory training course for internal medicine residents in South Korea.⁷ Moreover, efforts are being made to establish abdominal ultrasound practice training at training hospitals and various academic societies.⁸

In the wake of the COVID-19 pandemic, the educational paradigm, particularly in the medical field, has witnessed a rapid shift toward online teaching and learning.^9,10 These shifts may be noticeable in real-world fields, such as medical ultrasound training, where the balance between theoretical knowledge and practice is important.^11,12 Furthermore, this trend appears to lead to a surge in the dependence on digital platforms, posing new challenges to medical education.¹⁰ This change in education methods may be applied to abdominal USG learning. Practicing USG using a phantom model and repetitive learning for the ultrasound anatomy and disease findings on a digital platform are expected to improve the efficiency of abdominal ultrasound learning.¹³ On the other hand, there is a lack of objective standards for the curriculum and evaluation of the effectiveness of education and verified certification in training programs of upper abdominal USG.

Thus, this study compared the effects of a 30-minute online (via digital platform) and offline (face-to-face) lecture for upper abdominal USG education. In addition, this study also evaluated the effectiveness of a 30-minute upper abdominal USG lecture for internal medicine (IM) residents and gastroenterology (GI) fellows.

1. Study population

Forty-eight physicians were recruited from Ulsan University Hospital and Kosin University Gospel Hospital, which are tertiary and training hospitals in South Korea. They participated in the study voluntarily. This study included 13 IM residents and 12 GI fellows in the online education group, as well as 20 IM residents and 3 GI fellows in the offline education group. The Institutional Review Board of Ulsan University Hospital (IRB no. 2022-10-004) and Kosin University Gospel Hospital (IRB No. 2020-09-033) approved this study. The personal information of the participants and test scores were anonymized before analysis by indicating only whether they were internal medicine residents or gastroenterology fellows.

2. Education methods for abdominal USG

1) Online lecture

Online education was conducted via Google Classroom,¹⁴ which allowed participants to access the platform freely. The online training sequence included a pre-lecture test, a 30-minute lecture, and a post-test. All participants accessed Google Classroom and took the pre-lecture test, 39 short-answer questions, to submit their results first. For 30 minutes, they watched a pre-recorded lecture and then retook the post-lecture test, 39 short-answer questions, to submit their results. Google Classroom automatically recorded the login details of each participant, with the settings configured to prevent duplicate viewings and to enable participant identification (Fig. 1).

Figure 1. Study design. Before and after a short lecture, the physicians (Internal medicine residents and gastroenterology fellows) took a test with 39 slides consisting of still images of liver ultrasonography and the related short-answer questions.

2) Offline lecture (face-to-face lecture)

The same method as the online training sequence was applied to the offline setting. The method also included a pre-lecture test, a 30-minute in-person lecture, and a post-lecture test (Fig. 1). Both the online and offline lectures were identical in all aspects of the mode of instruction because the online and offline lectures were conducted by the same instructor, covering the same content for the same duration.

3. Test question composition

The test comprised questions evaluating the knowledge of the anatomical structure in abdominal ultrasound, liver segment, and operating ultrasound equipment. The test was meticulously structured to assess a comprehensive range of ultrasound- related knowledge, comprising 39 questions in total. The test encompassed 23 questions pertaining to the structure of the liver, 11 questions pertaining to the segment of the liver, and five questions focused on the optimal techniques for acquiring USG images. Both the pre-lecture test and post-lecture test had identical questions, but the order was randomized to prevent memorization. The participants completed a pre-lecture test, attended a non-interactive lecture on abdominal ultrasonography, and then retook the same test with the questions in a randomized order. Furthermore, the correct answers were not provided to the participants after the pre-lecture test to assess the effect of lecture-based education alone, and a post-lecture was administered after an online or offline lecture. Fig. 2 presents examples of short answer questions used in this study.

Figure 2. Examples of short-answer questions in the test of this study.

4. Statistical analysis

The categorical variables are presented as frequencies and percentages. The continuous variables are presented as the mean values±standard derivation. The Pearson χ² test (or Kruskal–Wallis test) was conducted for the categorical variables, and a t-test (or Mann–Whitney test) was used to compare the continuous numerical variables. A paired t-test was also conducted for each group, and an educational method was used to compare the scores before and after the lecture. A p-value <0.05 was considered significant. Data processing and statistical analyses were conducted using Statistical Package for the Social Sciences (SPSS version 24; IBM Co.), and graph creations were performed using GraphPad-Prism (version 10.1.2; GraphPad Software Inc.).

1. Baseline characteristics of the study population

Among 48 physicians, the online lecture group (n=25) had 13 IM residents (52%) and 12 GI fellows (48%), and the offline lecture group (n=23) had 20 IM residents (87.0%) and three GI fellows (13.0%). The rate of previous USG education for online and offline was nine (36.0%) and seven (30.4%), respectively (p=0.919). The rate of previous USG experience between the two groups was not significantly different between groups (p=0.301). In the online lecture group, 19 (76%) physicians had no USG experience, and six (24%) physicians had more than 10 USG experiences; in the offline lecture group, 21 (91.3%) physicians had no experience, and two (8.7%) physicians had more than 10 USG experiences (Supplementary Table 1).

2. Comparison of pre-lecture test and post-lecture test in total participants

The mean pre-test scores in the online and offline lecture groups were 16.7 (±8.6) and 7.3 (±6.1), respectively (p=0.003) (Supplementary Table 1). After one-time USG education, there was a significant increase in the test scores in IM residents (online and offline settings) and GI fellows (online setting) (p<0.0001, <0.0001, and p=0.0035, respectively) (Fig. 3A, 3B, 3D). On the other hand, although there was a trend of score improvement among GI fellows in the offline lecture group, statistical significance was not achieved because of the small number of participants (p=0.400) (Fig. 3C).

Figure 3. Comparison of the pre-test and post-test scores after a one-time ultrasonography lecture. The changes in the test scores between the pre- and post-tests were statistically significant in the offline lecture in IM residents (A) and online lecture in IM residents (B). The changes in test scores between pre- and post-test were not significant in offline lectures in GI fellows (C) but significant in online lectures in GI fellows (D). IM, internal medicine; GI, gastroenterology.

3. Comparison of delta-core between the online and offline lecture groups in IM residents and GI fellows

The delta scores after a one-time upper abdominal USG lecture were similar to the online and offline groups in total population (8.8±4.3 vs. 7.8±3.7, respectively; p=0.406) (Table 1, Fig. 4A). Similarly, the delta scores were similar in the online and offline groups within IM residents (9.0±4.5 vs. 8.4±3.6, respectively; p=0.927) (Table 1, Fig. 4B) or GI fellows (7.3±3.8 vs. 7.3±3.0, respectively; p=0.986) (Table 1, Fig. 4C). In addition, no significant difference in the delta scores was observed between the IM residents and GI fellows in the total population (8.8±4.1 vs. 7.3±3.6, respectively; p=0.290) (Fig. 4D). Subgroup analysis showed that this lack of significant difference persisted between IM residents and GI fellows after the online (9.0±4.5 vs. 7.3±3.0, p=0.537) and offline lectures (8.4±3.6 vs. 7.3±3.8, p=0.485).

Table 1 . Comparison of the delta-score according to the type of lecture and participant

Trainee	Delta-score (online)	Delta-score (offline)	p-value
Total population	8.8±4.3	7.8±3.7	0.406
Internal Medicine residents group	9.0±4.5	8.4±3.6	0.927
Gastrointestinal fellows group	7.3±3.8	7.3±3.0	0.986

Values are presented as mean±standard deviation.

Figure 4. Comparison of the delta scores after education according to the education method and study population. The delta-score after a one-time lecture was similar in the online and offline groups in total population (8.8±4.3 vs. 7.8±3.7, respectively; p=0.406) (A). In the IM resident group, the delta-score was similar after online and offline lectures (9.0±4.5 vs. 8.4±3.6, respectively; p=0.927) (B). In the GI fellow group, the delta-score was similar after online and offline lectures (7.3±3.8 vs. 7.3±3.0, respectively; p=0.986) (C). There was also no difference between the IM resident and GI fellows in the total population (8.8±4.1 vs. 7.3±3.6, respectively; p=0.290) (D). IM, internal medicine; GI, gastroenterology.

In this multi-center study, comparable effectiveness of a one-time upper abdominal USG lecture was observed between the online and offline groups. In addition, the education effect of a 30-minute upper abdominal USG lecture was statistically significant in the IM residents and GI fellows. To the best of the authors' knowledge, this is the first study to compare the effectiveness of online lectures via Google Classroom and offline lectures in upper abdominal USG training for physicians.

Abdominal USG is a test in which the sensitivity can vary according to the operator’s skill, understanding of the USG anatomy, and patient’s condition. A considerable learning period was also proficient.¹³ Discussions and debates about the type of education and duration of education might be ongoing. Nevertheless, several studies have shown that the educational effect of abdominal ultrasound education is revealed in the study participants from various backgrounds. With a short time of education for medical students, 98.3% of participants visualized the kidney and bladder, and 78.9% of students accurately visualized the gallbladder in the subcoastal view.⁶ Another study compared the effects of early ultrasound education and delayed learning of first-year medical students.¹⁵ In addition, USG education can have a positive effect on understanding the anatomy in medical students' anatomy learning.¹⁶ The literature review showed that USG was necessary for an effective diagnosis and evaluation for primary physicians,¹⁷ and there was a study that a two-week weekend intensive program for family physicians was sufficient to gain the knowledge necessary to perform a USG examination.¹⁸ Another study showed that a two-day basic course for point-of-care USG (POCUS) has effectively conveyed the fundamental POCUS knowledge and skills.¹¹ USG training model for general surgery residents was also suggested.⁸

Medical education has traditionally been dominated by face-to-face education and apprenticeship education, especially in the context of medical skills education.¹⁹ Medical skills have been acquired through the process of applying them to patients under supervision after theoretical training based on classes.²⁰ Nevertheless, the development of technology and the pandemic phenomenon of COVID-19 have also brought various challenges to the environment of medical education. The necessity of online education was emphasized, and the success of online conferences accelerated the demands of online and blended learning, which were previously raised.^21,22 The effectiveness of these new education methods must be verified. This study showed that self-learning through a digital platform such as Google Classroom can be effectively applied to medical education.^14,23 Furthermore, many test questions in this study focused on the detailed anatomy of the liver, confirming that online sessions can significantly improve test scores within a short period.

This study had several limitations. First, the study populations for online and offline lectures were not matched and remained unadjusted for experiences for USG education, which could influence the comparability of the two groups. On the other hand, regardless of educational background, the current study showed that a one-time upper abdominal USG lecture was effective in learning USG-based anatomy. Second, the test questions in this study were not standardized. The questions in this study were about the detailed anatomy of the liver, and the scores of these questions also increased significantly after both online and offline lectures. Third, despite the efforts to reduce the testing effect by presenting the questions in a randomly assigned order, the possibility of a testing effect influencing the results cannot be excluded. Lastly, selection bias existed in the study population, which requires caution in generalization for the results of this study.

In conclusion, the effectiveness of an online, one-time upper abdominal USG lecture might not be inferior to an offline (face-to-face) lecture. Furthermore, the effect of one-time upper abdominal USG education appears to be significant in IM residents and GI fellows. Further randomized, matched study is needed to validate these outcomes.

Supplementary material is available at the Korean Journal of Gastroenterology website (https://www.kjg.or.kr/).

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