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The scratch test is unreliable for detecting the liver edge
W N Tucker1, S Saab, L S Rickman
1Department of Internal Medicine, University of California Davis Medical Center, San Diego, California, USA.
Journal of Clinical Gastroenterology
|December 31, 1997
Summary
The scratch test is an invalid and unreliable method for measuring liver span below the right costal margin. This physical examination technique showed poor correlation with ultrasound measurements.
Area of Science:
- Hepatology
- Clinical Examination
- Diagnostic Accuracy
Background:
- The scratch test is a traditional physical examination technique used to estimate liver size.
- Its clinical utility in accurately assessing liver span below the costal margin requires validation.
Purpose of the Study:
- To evaluate the validity and reliability of the scratch test for measuring liver span.
- To compare scratch test estimations with ultrasound measurements.
Main Methods:
- Prospective, double-blind study involving 22 patients and 11 examiners with varying training levels.
- Examiners used only the scratch test to measure liver edge length below the right costal margin.
- Comparison of scratch test measurements with ultrasound findings using linear regression and concordance correlation coefficient.
Main Results:
- Very poor correlation was observed between scratch test estimates and ultrasound measurements across all examiners.
- Measurement reliability among seven observers was 0.68, while the reliability of a single examiner was only 0.24.
- The scratch test demonstrated significant variability and inaccuracy in estimating liver span.
Conclusions:
- The scratch test is neither a valid nor a reliable method for assessing liver span below the right costal margin.
- Ultrasound is a more accurate and reliable tool for liver span measurement.
- Clinical reliance on the scratch test for this purpose is not recommended.