Uniform enlargement of the abdomen may be because of gas or fluid in the abdomen. In the former there is tympanic note on percussion while in the latter there is dullness.
Because the fluid accumulates in the flanks, the areas of dullness on both sides resembles a horse-shoe shape.If fluid is suspected-
- Perform percussion with the patient lying on his back
- Then change patien to lateral position and percuss on each side.
In these maneuvers , the upper flank will be resonant as the fluid is pushed down by gravity to the lower flank, a phenomenon called shifting dullness.
Percussion also helps to delineate the outline of an enlarged viscera or abdominal tumour.
An enlarged spleen is dull note on percussion whereas from an enlarged left kidneyis resonant note because of the intervening colon.
The upper border of the liver can be accurately determined by percussion. Percussion is started anteriorly in the right midclavicular line from second intercostals space downwards and repeated in the anterior mid and posterior axillary lines and the scapular line posteriorly.
The normal liver dullness is in the fifth space in the midclavicular, seventh space in the anterior axillary and ninth space in the scapular lines.
The upper border of the liver may be percussed in the fourth or third space in the midclavicular line in patients with amebic abscess of liver or any abscess on the superior surface of the liver.
The liver dullness is lower in the sixth or seventh right intercostals space in emphysema, right sided pneumothorax, when there is air in the peritoneal cavity, acute yellow atrophy of the liver and in terminal cirrhosis.
