In confirming a diagnosis of cirrhosis, a disease which involves hepatocellular (liver cell) death replaced by scar tissue, the only true definitive diagnostic procedure is a liver biopsy.
However, when an invasive procedure as such is contraindicated, liver enzyme levels (LFTs) may be tested for in blood serum to estimate overall function (or lack thereof in vast cell death throughout the organ as seen in cirrhosis) of hepatocytes (liver cells). These enzymes include: alanine aminotransferase (ALT), aspartate aminotransferase (AST), and often gamma-glutamyl transferase (GGT). Also an abdominal ultrasound (US) of the right upper quadrant can determine the consistency of the liver, i.e. density of sanguinous living tissue versus dead scar tissue. Together, the serum enzyme levels and an US showing widespread hepatic scar tissue (indicative of cirrhosis) are enough to point to cirrhosis. However, true definitive evidence, as aforementioned, is only confirmed via US- or CT-guided tissue biopsy.
*note: CT stands for Computed Tomography, as in the old term "CAT-scan"
