Histopathologic variability between the right and left lobes of the liver in morbidly obese patients undergoing roux-en-Y bypass

Background & Aims: Nonalcoholic fatty liver disease (NAFLD) has been shown to occur in > 90% of significantly obese patients. At present, diagnosis of the more severe form of NAFLD, nonalcoholic steatohepatitis (NASH), requires a liver biopsy. Conflicting data exist on the degree of sampling variability seen with percutaneous liver biopsy. Our aim was to assess for significant regional differences in histopathology between the right and left lobes of the liver in morbidly obese patients undergoing bariatric surgery. Methods: Morbidly obese patients undergoing bariatric surgery at Wilford Hall Medical Center were eligible for study enrollment. Patients with chronic liver disease other than NAFLD were excluded. All patients underwent intra-operative liver biopsy, one from the right lobe and one from the left lobe, with a 14-gauge Tru-cut biopsy needle. Histopathologic features of NAFLD were compared by a hepatopathologist who examined biopsy specimens from the 2 hepatic lobes and was blinded to patient identification and site of origin of biopsy. Agreement between the 2 biopsy specimens was assessed by using the kappa coefficient. Results: Forty-three patients (predominantly female) with body mass index median of 46.2 kg/m(2) were enrolled. Agreement for steatosis was 93% (kappa = 0.91), inflammation 74% (kappa = 0.58), ballooning necrosis 84% (kappa = 0.73), fibrosis 98% (kappa=0.96), and for the NAFLD activity score :5 was 93% (kappa = 0.83). Conclusions: Minimal variability was found for steatosis, NAFLD activity score >= 5, and fibrosis in samples of liver obtained from the right and left lobes of the liver in a group of morbidly obese, predominately female patients undergoing bariatric surgery. Histopathologic findings of necroinflammation appear to have the greatest degree of sampling variability. In contrast with previously published data, excellent agreement was seen for fibrosis in biopsy specimens obtained at surgery from right and left lobes of the liver.