THE SCRATCH TEST IS UNRELIABLE FOR DETECTING THE LIVER EDGE

To determine the validity and reliability of the scratch test method f or estimating the liver span below the right costal margin, we perform ed a prospective double-blind study using multiple examiners at differ ent levels of training. Twenty-two patients were examined by 11 observ ers using only the scratch test. Measures of liver edge length below t he right costal margin using the scratch test were compared with those by ultrasound. The validity of the scratch test was determined by sim ple linear regression and the concordance correlation coefficient. The re was very poor correlation between the scratch test estimates and ul trasound measurements for all examiners. Measurement reliability, esti mated using generalizability theory, for seven observers who examined the same nine patients was 0.68. The reliability of a single examiner was 0.24. The scratch test method for measuring the liver edge span be low the right costal margin war neither a valid nor reliable method of physical examination.