From the 1 Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS, Brasil; 2 Irmandade Santa Casa de Misericórdia de Porto Alegre, Porto Alegre, RS, Brasil ( 1 Federal University of Health Sciences of Porto Alegre, Porto Alegre, RS, Brazil; 2 Irmandade Santa Casa de Misericórdia de Porto Alegre, Porto Alegre, RS, Brazil). How to cite this article: BYPASS VS. SLEEVE AND ITS EFFECTS IN NON-ALCOHOLIC FATTY LIVER DISEASE: WHAT IS THE BEST TECHNIQUE? . ABCD Arq Bras Cir Dig. 2020;33(3):e1549. DOI: /10.1590/0102-672020200003e1549 ABSTRACT - Background: Strongly associated with obesity, non-alcoholic fatty liver disease is considered the hepatic manifestation of the metabolic syndrome. It presents as simple steatosis and steatohepatitis, which can progress to cirrhosis and its complications. Among the therapeutic alternatives is bariatric surgery. Aim: To compare the efect of the two most frequent bariatric procedures (sleeve and bypass) on liver disease regarding to epidemiological, demographic, clinical and laboratory parameters. Methods: The results of intraoperative and 12 months after surgery liver biopsies were used. The NAFLD activity score (NAS) was used to assess and compare the stages of liver disease. Results: Sixteen (66.7%) patients underwent Bypass procedure and eight (33.3%) Sleeve. It was observed that the variation in the NAFLD activity score was signifcantly greater in the Bypass group than in Sleeve (p=0.028) and there was a trend regarding the variation in fbrosis (p=0.054). Conclusion: Both surgical techniques were efective in improving the hepatic histology of most operated patients. When comparing sleeve and bypass groups, bypass showed better results, according to the NAS score. HEADINGS: Bypass. Sleeve. Non-alcoholic fatty liver disease. Morbid obesity. Bariatric surgery. RESUMO - Racional: Fortemente associada à obesidade, a doença hepática gordura não alcoólica é considerada a manifestação hepática da síndrome metabólica. Ela apresenta-se como esteatose simples e esteato-hepatite, podendo evoluir para cirrose e suas complicações. Entre as alternativas terapêuticas está a cirurgia bariátrica. Objetivo: Comparar o efeito sobre a doença hepática dos dois procedimentos bariátricos mais frequentes - sleeve e bypass - e comparar dados epidemiológicos, demográfcos, parâmetros clínicos e laboratoriais. Métodos: Utilizou-se o resultado das biópsias hepáticas realizadas no intra-operatório e 12 meses após a operação. O NAFLD activity score foi utilizado para avaliar e comparar os estágios da doença hepática. Resultados: Dezesseis (66,7%) pacientes foram submetidos ao bypass e oito (33,3%) ao sleeve. Observou-se melhora signifcativa no IMC e glicemia nas duas técnicas cirúrgicas enquanto que os níveis de fosfatase alcalina, ferritina, Gama-GT e TGP reduziram com signifcância apenas no grupo bypass. A redução no NAFLD activity score foi signifcativamente maior no grupo bypass que no sleeve (p=0,040). Conclusão: Ambas as técnicas foram efcazes em promover a melhora da histologia hepática da maior parte dos pacientes operados. Quando comparadas o bypass apresentou melhores resultados. DESCRITORES: Bypass. Sleeve. Doença hepática gordurosa não alcoólica. Obesidade mórbida. Cirurgia bariátrica. Original Article BYPASS VS. SLEEVE AND ITS EFFECTS IN NON-ALCOHOLIC FATTY LIVER DISEASE: WHAT IS THE BEST TECHNIQUE? Bypass vs. sleeve e seus resultados na doença hepática gordurosa não alcoólica: Qual a melhor técnica? Marcos Bertozzi GOLDONI 1 , Paulo Roberto Ott FONTES 1 ,Marcela Menuci GUIMARÃES 1 , João Alfredo DIEDRICH-NETO 1 , Tiele NOGUEIRA 1 , Uirá Fernandes TEIXEIRA 1 , Caroline Becker GIACOMAZZI 1 , Guillermo KISS 2 , Sérgio Ricardo PIONER 2 , Pablo Duarte RODRIGUES 1 Financial source: none Confict of interest: none Received for publication: 23/03/2020 Accepted for publication: 16/07/2020 Correspondence: Marcos Bertozzi Goldoni E-mail: mbgoldoni@hotmail.com ABCD Arq Bras Cir Dig 2020;33(3):e1549 DOI: https://doi.org/10.1590/0102-672020200003e1549 www.instagram.com/abcdrevista www.facebook.com/abcdrevista www.twitter.com/abcdrevista 1/5 ABCD Arq Bras Cir Dig 2020;33(3):e1549 Perspectives Non-alcoholic fatty liver disease is considered the hepatic manifestation of the metabolic syndrome and has bariatric surgery as a alternative treatment. Both most frequent techniques – sleeve and bypass – were efective in promoting liver histological improvement. When compared using the NAFLD activity score, bypass provided better results being the surgery of choice for this situation. A larger number of studies, mainly randomized control trials, are needed to confrm this hypothesis. Central message When comparing the liver efects of the two most frequent bariatric procedures – sleeve and bypass – both were efective in promoting histological improvement of non-alcoholic fatty liver disease. When compared, bypass provided better results.