Researchers are trying to identify predictors for gastroesophageal reflux disease after sleeve gastrectomy.

Subjects will undergo an upper endoscopy with EndoFLIP before sleeve gastrectomy to measure parameters from endoscopy and EndoFLIP device to develop a prediction model for post-operative gastroesophageal reflux disease. Subjects will undergo a repeat upper endoscopy with EndoFLIP at 6 months if an upper endoscopy is clinically indicated after surgery and complete questionnaires during follow-ups up to 5 years.

Inclusion Criteria:

• Adult patients > 18 years
• BMI 30 or greater kg/m2
• Participants can give a consent to the procedure
• Participants have no contraindications to LSG (gastric ulceration)

Exclusion Criteria:

• Participants who have LA grade C or D esophagitis, Barrett mucosa or peptic stricture.
• Patients who have evidence of a major motility abnormality defined by the Chicago classification version 3.0 (achalasia, absent contractility, esophagogastric junction outflow obstruction, distal esophageal spasm, or hypertensive peristalsis)
• Patients with hiatal hernia > 3 cm
• Patients with previous esophageal or stomach surgery