Investigation:
Examine ascites fluid: turbidity suggests infection
or tumor, milky fluid suggests chylous ascites
(lymphatic disruption due to trauma, cirrhosis,
tumor), dark brown fluid suggests biliary tract
perforation.
• Serum ascites albumin gradient (SAAG): obtain
serum albumin level and compare. Interpret as
discussed above.
• Cell count + differential: ↑ neuts are consistent with
peritonitis
• Biochemistry: glucose, protein.
• Gram stain and culture if indicated. One pathogen
(usually enteric organisms) may be spontaneous
peritonitis, but multiple bacteria suggests 2°
peritonitis from ruptured viscus or abscess.
Elicit shifting dullness or fluid thrill to confrim ascites