How Strongly do Physical Examination Estimates and Ultrasonographic Measurements of Liver Size Correlate? A Prospective Study.

BACKGROUND: Liver size assessed by physical exam and ultrasound has long been used to gain useful clinical information. The size measurements obtained by these modalities have been difficult to compare as they are measured in two different axes (trans-axial versus mid-clavicular). Our objective is to identify a measurement correlation between ultrasound and physical exam liver size findings. We aim to develop a correction factor where by the liver size can be translated between the measured trans-axial size obtained by ultrasound and physical exam size when measured in the mid-clavicular line.

METHODS: We conducted a prospective study including one hundred and one adult patients with liver disease undergoing liver biopsy between April 2008 and November 2008 at Penn State Health Milton S. Hershey Medical Center.Liver measurements were obtained by physical exam and ultrasound as performed by a single hepatologist.

RESULTS: The average physical exam size using the mid-clavicular approach was 8.9 cm +/- 1.13. On ultrasound, the average trans-axial measurement was 14.3 cm +/- 1.6. A ratio was made between measurements from the mid-clavicular line physical exam size and trans-axial ultrasound size, and found to have a mean correction factor of 1.6 +/- 0.14. The correction factor was applied to the physical exam-determined liver size and compared to ultrasound findings, with 76% of values (77/101) falling within 10% of the ultrasound-determined liver size.

CONCLUSION: This study proves a strong correlation exists between physical examination estimates of liver size and the measured size on ultrasonogaphy. Multiplying the percussed liver span by a correction factor consistently yields accurate predictions of the transaxial liver span.