This study will include all eligible patients who have undergone or who will undergo a laparoscopic gastric bypass procedure at Madigan Army Medical Center using a specific surgical technique developed by the Principal Investigator. Traditionally, our surgeons have used a standardized technique that included use of a circular stapler to perform the anastomosis of the stomach pouch to the small bowel. The Principal Investigator developed a new technique with multiple modifications of the previous technique, including use of a totally linear stapled anastomosis. These techniques will be labeled OLD and NEW for the remainder of this document. The NEW technique was first utilized in May 2008 and has now been widely adopted by the majority of bariatric surgeons at Madigan Army Medical Center. This study will include both a retrospective review of all patients who have undergone this procedure, as well as a prospective observational study of all future patients undergoing this procedure. At this time, approximately 75 patients have undergone this procedure and will all be included in the retrospective review. The investigators estimate that 150 to 200 of these procedures will be performed at Madigan per year over the next 2 years, and will be included in the prospective observational arm of the study. The investigators anticipate a total sample number of 400 patients if the investigators collect data for the next two years.

Hypothesis: The NEW technique of gastric bypass allows for safe and rapid performance of a laparoscopic gastric bypass. The NEW technique will result in shorter operative times compared to the OLD technique, and no significant difference in postoperative complications.

The methods of the retrospective arm of the study will involve abstracting of key variables of interest from review of each patient's electronic medical record, including the inpatient electronic record at the time of surgery and any subsequent readmission, and all outpatient visits identified on AHLTA. The key outcome variables of interest will be the early and late complication profile of this procedure, the impact on weight loss and control of weight-related comorbidities, the operative time required for the procedure, and the operative difficulty of the procedure as assessed by intraoperative complications and blood loss. All data will be abstracted to a standardized spreadsheet maintained by the PI, and a full listing of the study variables is attached. The prospective arm of the study will involve collection of the same data in a prospective manner, with the addition of direct conversations with the operating surgeon and/or resident to clarify any ambiguities in the electronic record.

The data analysis plan will involve simple descriptive statistics for all demographic variables, such as age, body mass index (BMI), gender, etc. Descriptive analysis of outcome data will be performed, including the short and long term complication profile of the NEW operation. Weight loss will be calculated as the percentage of the BMI lost at each time point, and will be analyzed by a paired sample t-test, with significance set at p<0.05. Operative times will be compared between different staff surgeons and different PGY levels using analysis of variance (ANOVA) with post-hoc analysis using Bonferroni test and Tamhanes T2. Complications will be compared among these same groups using chi-square analysis. As the operative times and complication profile associated with the previously performed method of gastric bypass (OLD) are known and have been published, the investigators will also compare our outcomes with this new method to our outcomes with the old method using chi-square, student's t-test, and paired t-test to compare each surgeon's operative times with the old technique and the new technique.

Inclusion Criteria:

• scheduled for a laparoscopic gastric bypass

Exclusion Criteria:

• Patients undergoing laparoscopic gastric bypass using any method other than the totally linear stapled method

Patients who have undergone or who will undergo a laparoscopic gastric bypass procedure at Madigan Army Center using a specific surgical technique developed by the Principal Investigator.