RESEARCH ARTICLE A Prospective Randomized Study Comparing Patients with Morbid Obesity Submitted to Laparotomic Gastric Bypass with or without Omentectomy Attila Csendes & Fernando Maluenda & Ana Maria Burgos Received: 25 April 2008 / Accepted: 4 August 2008 # Springer Science + Business Media, LLC 2008 Abstract Background Visceral fat, especially the greater omentum, seems to be an important factor in the development of some metabolic disturbances such as insulin resistance, hyper- glycemia, and dyslipidemia. Therefore, we wanted to evaluate the influence of resecting or leaving in situ the greater omentum in a group of patients with morbid obesity. Methods Seventy patients with morbid obesity were sub- mitted to laparotomic resectional gastric bypass and an omentectomy was randomly performed in some patients. Body mass index (BMI), serum levels of sugar, insulin, total cholesterol, and triglycerides were determined prior to surgery and followed up on for 2 years afterwards. Results Two years after surgery, no differences were seen in BMI levels in either group. Blood sugar levels, serum insulin, total cholesterol levels, and serum triglycerides had similar values in both groups. Arterial hypertension had similar behavior. Conclusions Based on these results, omentectomy is not justified as part of bariatric surgery. Its theoretical advan- tages are not reflected in this prospective random trial. Keywords Morbid obesity . Gastric bypass . Omentectomy The worldwide increase in obesity has been extensively documented. This condition is associated with a number of adverse health effects. Several studies have suggested that the increase in visceral fat seems to be an important factor for developing several metabolic comorbidities such as insulin resistance, hyperglycemia, and dyslipidemia [1–6]. Different types of bariatric surgery have been employed in these patients in order to decrease weight, improve comorbidities, and improve their quality of life. Among these options, gastric bypass is, up to now, the “gold standard” as the surgical treatment of choice for patients with morbid obesity [7–9]. There is evidence that visceral adipose tissue is particularly pernicious to health [6]. Therefore, our hypothesis was that the removal of the greater omentum during gastric bypass may have an additional beneficial effect on the metabolic comorbidities associated to morbid obesity. Consequently, we performed a prospective random study evaluating the influence of the removal of the omentum or leaving it in situ, in a group of patients with morbid obesity evaluated prior to surgery and followed up on for 2 years afterwards. Material and Methods 1. Patients studied: In this prospective and random study, a total of 70 patients with morbid obesity were included. All gave their written consent to be included in this study, which lasted between August 2000 and January 2003. None had previous abdominal surgery. Patients with arterial hypertension, diabetes, hyper- insulinemia, and dyslipidemia were included in this study. All were evaluated prior to surgery and followed up on for 2 years afterwards. 2. Method of randomization: After a laparotomy, and if the patient was completely suitable for any type of surgical procedure, a small card was taken out blindly from an envelope which contained 35 cards marked OBES SURG DOI 10.1007/s11695-008-9660-2 A. Csendes : F. Maluenda : A. M. Burgos Department of Surgery, University Hospital, University of Chile, Santiago, Chile A. Csendes (*) Department of Surgery, Hospital J. J. Aguirre, Santos Dumont 999, Santiago, Chile e-mail: acsendes@redclinicauchile.cl