Evidence Base: Liver & Ascites

Physical Exam

How helpful is physical examination in assessing liver size?

The exact dimension of a normal liver span in the midclavicular line have been reported as anywhere from 6cm to 15 cm but generally is considered as less than 12 cm. Studies show that clinicians underestimate the liver span as compared to that measured by ultrasonography. However, these studies found that the estimated span correlates moderately with the span by imaging. They also showed that the estimates where strongly influenced by the examiner’s technique, with a heavier percussive stroke yielding a smaller span estimate.

The data shows that while there is a high likelihood of the liver actually extending below the costal margin if the clinician detects this on exam. However, this finding is a weak predictor of having an enlarged liver (LR 1.7).

Approximately 1/2 of the livers found to extend below the costal margin by liver scintiscans are not be palpable; this appears to depend on the consistency of the liver.

Being able to palpate a liver edge does not necessarily mean the liver is enlarged or diseased but does increase the likelihood of hepatomegaly. You must also take into account the vertical liver span and overall clinical context of the patient. At the same time, a nonpalpable liver edge does not rule out hepatomegaly but does reduce its likelihood. This is instrumental in those settings of low prior probability of liver disease in indicating that further examination is likely to have little yield if the liver cannot be felt. (Naylor)

Conclusion

Naylor suggests that after having elicited the history and other physical signs of liver disease, the added value of a detailed physical examination of the liver is uncertain. In general, diagnostic tests yield little at the extremes of prior probability. In keeping with this, there is less yield from liver examination in persons who are not suspected of having liver disease or who are obviously suffering from some hepatobiliary complaint.

They go on to recommend a triaged approach to examination of the liver

1. Low probability of disease, liver edge not palpable:
   If the pretest probability of liver disease is low, begin by palpating the lower liver border in the MCL in situations of low probability of liver disease. If the liver edge is not palpable on an adequate exam, no further examination in patient. Light percussion may be used to confirm lack of extension of the liver edge below the costal margin and/or guide further palpation.
2. Low probability of disease, liver edge palpable:
   With a palpable lower edge, MCL span can be ascertained by light percussion of the upper border. A span of less than 12 to 13 cm reduces the probability of hepatomegaly.
3. High probability of disease, liver edge not palpable:
   If there is a high probability of liver disease and the liver is not palpable, measuring span by percussion alone may also be helpful as tables of norms have been published, although these apply to moderate or heavy percussion methods.
4. High probability of disease, liver edge palpable:
   Palpate specifically to assess the quality of the liver edge only if there are signs of liver disease, including unequivocal hepatomegaly. Auscultation over the liver has a limited role in examination.

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How helpful is physical examination in detecting ascites?

No single sign has been found to be both sensitive and specific. The most powerful physical exam findings for the diagnosis of ascites (LR+ column in table below) are a positive fluid wave and shifting dullness. The most useful physical exam finding arguing against ascites (LR- column in table below) is the absence of bulging flanks, flank dullness, or shifting dullness.

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