Nonalcoholic fatty liver disease (NAFLD) is a chronic condition that can progress to cirrhosis and hepatocellular cancer. The most progressive form of NAFLD is nonalcoholic steatohepatitis (NASH). Currently, the only method to diagnose NASH is with a liver biopsy; however. sampling error may limit diagnostic accuracy. We investigated the discordance of paired liver biopsies in individuals undergoing gastric bypass.Methods
Two liver biopsies, composite size of ≥25 mm and ≥8 portal tracts (PTs), were obtained from the left lobe in 31 subjects. Group 1 included specimens at least 15 mm in length with ≥4 PTs compared to a second biopsy of at least 10 mm and ≥4 PTs (Group 2).Results
The mean specimen size (number of PTs) for group 1 was 20.4 ± 4.2 mm (11.7 ± 5.5 PTs) and group 2 was 16.1 ± 5.3 mm (8.2 ± 4.1 PTs). Prevalence of NASH was 26% in Group 1 and 32% in Group 2. Sampling discordance was greatest for portal fibrosis (26%), followed by zone 3 fibrosis (13%) and ballooning degeneration (3%). The negative predictive values from Group 1 liver biopsies for NASH and portal fibrosis were only 83% and 67%, respectively.Conclusions
The results demonstrate that significant sampling variability exists in class 2 and 3 obese individuals undergoing screening liver biopsies for NAFLD. The degree and histopathological discordance is dependent upon zonal location and types of injury. Nevertheless, a 25-mm biopsy specimen without zone 3 cellular ballooning or fibrosis appears adequate to exclude the diagnosis of NASH.