ORIGINAL CONTRIBUTIONS Incidence and Risk Factors for Cholelithiasis After Bariatric Surgery Hernán M. Guzmán 1 & Matías Sepúlveda 1,2 & Nicolás Rosso 3 & Andrés San Martin 2 & Felipe Guzmán 4 & Hernán C. Guzmán 1,2 # Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract Background Obesity and rapid weight loss after bariatric surgery (BS) are independent risk factors for development of choleli- thiasis (CL), a prevalent disease in the Chilean population. This study aimed to determine the incidence of CL in obese Chilean patients 12 months after BS and identify risk factors for development of gallstones. Methods Retrospective study of patients who underwent BS in 2014. Patients with preoperative negative abdominal ultrasound (US) for CL and follow-up for at least than 12 months were included. Patients underwent US at 6 months and 12 months. We analyzed sex, age, hypertension, dyslipidemia, type 2 diabetes mellitus, body mass index (BMI), surgical procedure, percentage of excess BMI loss (%EBMIL) at 6 months, and BMI at 6 months. Results Of 279 patients who underwent bariatric surgery during 2014, 66 had previous gallbladder disease and 176 met the inclusion criteria (82.6%), while 54.6% were female. The mean age was 37.8 ± 10.5 years and preoperative BMI was 37.5 kg/m 2 . BMI and %EBMIL at 6 months were 27.8 ± 3.3 kg/m 2 and 77.9 ± 33.6%, respectively. At 12 months after BS, CL was found in 65 patients (36.9%). Hypertension turned out to be protective against occurrence of gallstones at 1 year with an OR 0.241. Conclusions Incidence of CL was up to one-third of the patients followed up for 12 months after BS. Excessive weight loss and other variables studied did not increase risk. Hypertension seems to be protective against gallstone formation, but this result needs further analysis. Keywords Obesity . Bariatricsurgery . Cholelithiasis . Weight loss . Sleevegastrectomy . Sleeve gastrectomy with jejunal bypass . Roux-en-Y gastric bypass Introduction Bariatric surgery is commonly accepted as the best treatment for obesity and related comorbidities, and an increasing num- ber of patients are undergoing a weight-loss procedure [1]. Chile has one of the world’ s highest rates of cholelithiasis (CL), and CL prevalence could be as high as 51% in women [2]. Risk of CL can increase in obese people fourfold com- pared with that in the non-obese population [3]. Some sur- geons perform simultaneous cholecystectomy with bariatric surgery, while others postpone gallbladder removal unless pa- tients are symptomatic [4]. As a high weight correlates with gallstone formation, there is also a high risk of developing CL after bariatric surgery. This is strongly related to rapid weight * Matías Sepúlveda drmsepulveda@gmail.com Hernán M. Guzmán hernus87@gmail.com Nicolás Rosso nicorosso@gmail.com Andrés San Martin andresesanmartin@gmail.com Felipe Guzmán felipe.igm26@gmail.com Hernán C. Guzmán hguzmanc@mi.cl 1 Bariatric and Metabolic Surgery Center, DIPRECA Hospital, Vital Apoquindo 1200, Las Condes, Santiago, Chile 2 Escuela de Medicina, Universidad Diego Portales, Av. Ejército Libertador 141, Santiago, Chile 3 Hospital San Camilo, Miraflores 2085, San Felipe, Santiago, Chile 4 Escuela de Medicina, Universidad de Santiago, Av Libertador Bernardo O’Higgins 3363, Santiago, Chile Obesity Surgery https://doi.org/10.1007/s11695-019-03760-4