Katherine Egan1,2, Aoife Courtney3, Hannah Hession3, Joseph Morris4, Therese Coleman5, Czara Kennedy1,2, Aimee Brennan1, Donal O’Shea1,5, Andrew Hogan1,6, Naomi Fearon2, Waqas Butt2, Lindsey Clarke4, Omar El-Sherif7, Helen Heneghan1,2
1Obesity Immunology Group, Education and Research Centre, St. Vincent’s University Hospital, Dublin, Ireland;
2Department of Upper Gastrointestinal and Bariatric Surgery, St. Vincent’s University Hospital, Dublin, Ireland;
3Centre for Obesity Management, St. Colmcille’s Hospital, Dublin, Ireland;
4Department of Pathology, St. Vincent’s University Hospital, Dublin, Ireland;
5Department of Dietetics, St. Vincent’s Private Hospital, Dublin, Ireland;
6Kathleen Lonsdale Institute for Human Health Research, Maynooth University, Maynooth, Ireland;
7Department of Hepatology, St. Vincent’s University Hospital, Dublin, Ireland
Background: Liver biopsy is the gold-standard investigation for metabolic dysfunction-associated steatotic liver disease (MASLD). However, it is not routinely performed to assess response to therapy, given its invasiveness and risks. Although multiple non-invasive tests have been identified, none have proven equal or superior to liver biopsy. The true histological improvement of MASLD following bariatric surgery is therefore unclear. This study aimed to characterise the impact of bariatric surgery on histologically confirmed MASLD.
Methods: Retrospective review of patients who had liver biopsies taken at both index bariatric surgery and subsequent revisional surgery at St. Vincent’s Hospital Group between 2017 and 2025. Biopsies were reviewed by two pathologists to assess and compare the grade of steatosis, fibrosis stage, and presence or absence of steatohepatitis.
Results: A total of 11 patients were identified. Revisional surgery was predominantly indicated for reflux, with the most common revisional procedures being conversion of sleeve gastrectomy or one-anastomosis gastric bypass to Roux-en-Y gastric bypass. Mean time between surgeries was 2.2 years, with a mean % total weight loss at time of revisional surgery of 22.4%. One hundred percent of patients (n=11) had histological evidence of MASLD at index surgery, which decreased to 30% (n=3) at revisional surgery. There was a significant improvement in steatosis grade following bariatric surgery (P=0.02). All patients with histological evidence of steatohepatitis (n=5) at index surgery had resolution on repeat biopsy. No patients with fibrosis (n=9) at index surgery had progression. Despite an overall improvement of fibrosis stage, this was not statistically significant (P=0.18).
Conclusions: Bariatric surgery is an effective treatment for MASLD, even where fibrosis has occurred. In patients with non-cirrhotic MASLD and obesity, bariatric surgery should be considered.
Keywords: Bariatric surgery; biopsy; metabolic dysfunction-associated steatotic liver disease (MASLD); liver; obesity
