The scratch test for determining the inferior hepatic margin
Still a valuable component of the physical exam
Evaluation of liver size by palpation is a basic component of the physical examination. Suspicion of an enlarged liver should prompt the clinician to examine for possible causes (Box 1) and investigate further with appropriate imaging such as ultrasonography. Palpation to detect the inferior liver margin may not be accurate or possible in certain clinical conditions (eg, obesity, abdominal distension, tenderness, or guarding). In such cases the scratch test may be useful. We describe the technique of the test and review the evidence base for its use.
The scratch test is a type of auscultatory percussion which was described as far back as 1840, and used to ascertain the size and form of various organs, including the heart and liver.2 The principle behind the scratch test is that the sound from a scratch on the skin overlying the relatively solid liver will be transmitted to a stethoscope located at another point over the liver better than a scratch not over the liver (ie, separated from the stethoscope by bowel or air).
Method for performing the scratch test3
The diaphragm of the stethoscope is placed on the xiphisternum (point C in Box 2).
The examiner repeatedly and lightly strokes…