The importance of routine liver biopsy in diagnosing nonalcoholic steatohepatitis in bariatric patients

Background: Nonalcoholic Steatohepatitis (NASH) commonly occurs in obese patients and predisposes to cirrhosis. Prevalence of NASH in bariatric patients is unknown. Our aim was to determine the role of routine liver biopsy in managing bariatric patients. Methods: Prospective data on patients undergoing Roux-en-Y gastric bypass (RYGBP) was analyzed. One pathologist graded all liver biopsies as mild, moderate or severe steatohepatitis. NASH was defined as steatohepatitis without alcoholic or viral hepatitis. Consecutive liver biopsies were compared to those liver biopsies selected because of grossly fatty livers. Results: 242 patients underwent open and laparoscopic RYGBP from 1998-2001. Routine liver biopsies (68 consecutive patients) and selective liver biopsies (additional 86/174, 49%) were obtained. Findings of cirrhosis on frozen section changed the operation from a distal to a proximal RYGBR The two groups were similar in age, gender, and BMI. The group with the routine liver biopsies showed a statistically significant larger preponderance of NASH (37% vs; 32%). Both groups had a similar prevalence of cirrhosis. Neither BMI nor liver enzymes predicted the presence or severity of NASH. Conclusions: Routine liver biopsy documented significant liver abnormalities in a larger group of patients compared with selective liver biopsies, thereby suggesting that liver appearance is not predictive of NASH. Liver biopsy remains the gold-standard for diagnosing NASH. We recommend routine liver biopsy during bariatric operations to determine the prevalence and natural history of NASH, which will have important implications in directing future therapeutics for obese patients with NASH and for patients undergoing bariatric procedures.