Do Physical Exam and Ultrasound Liver Size Findings Correlate? Teaching the Abdominal Examination Through Reflective Practice

Abstract

Introduction: Our primary objective was to identify a measurement correlation between liver sizes measured via the right midclavicular line physical exam (PE) method and trans-axial ultrasound (US) and then develop a correction factor whereby the liver size can be translated between the two measurements. We aspire to apply this correction factor as an educational tool to promote active learning in medical students learning how to accurately percuss the liver size. Methods: We performed a cross-sectional study including 101 adult patients with liver disease undergoing liver biopsy at the Penn State Health Milton S. Hershey Medical Center. Liver measurements were obtained by PE and trans-axial US liver size as performed by a single hepatologist. A correlation coefficient was calculated. For each patient, a ratio was made between measurements from the trans-axial US size and midclavicular line PE size to generate an average correction factor. Results: The average PE-determined liver size was 8.9 cm +/- 1.13. On US, the average trans-axial measurement was 14.3 cm +/- 1.6. An R factor was calculated at 0.7, indicating that there was a strong correlation between the measurements. We generated an average correction factor of 1.6 between the PE-determined liver size and trans-axial US measurementsfor each patient. Conclusion: A correlation exists between the two methods of obtaining liver size. The correction factor can play a significant role in allowing students to reflect on their PE technique. Students can percuss the liver size and multiply it by the correction factor, comparing that to the liver size observed on US. If there remains significant discrepancy between the two measurements, the student is able to reflect on his or her technique and can make an active effort to adjust it to percuss more accurate liver measurements. We aim to incorporate our method into our medical school curriculum. We suggest two strategies by which this can be accomplished: 1) Teaching students liver percussion on cadavers. Following percussion and subsequent incorporation of our correction factor, an experienced advisor can measure the US-determined liver size and compare it to the student's percussed liver span measurement. 2) Based in the classroom, students can practice the PE on each other or standardized patients. Once a student has percussed his or her interpretation of the liver size and multiplied in our correction factor, comparisons can be made to the US- determined measurement of the percussed liver.936_A Figure 1. Each patient is represented by a single diamond and corresponding measurements for the two exam methods are shown.936_B Figure 2. Midclavicular and transaxial measurements of the liver936_C Figure 3. Common liver size conversions using the correction factor