Variation between and within surgeons in the size and shape of the stomach after weight-loss sleeve gastrectomy, measured on three-dimensional CT scans

The three-dimensional CT (3D-CT) scans are research procedures. They are performed for this study at four timepoints — before surgery and at approximately 3 to 6 months, 12 to 18 months and 5 years after surgery — and in participants without reflux they are additional to usual clinical care and would not otherwise be undertaken. Each scan delivers an effective radiation dose of approximately 1.1 millisieverts. The sleeve gastrectomy itself is usual clinical care, chosen and performed on clinical grounds, and is not altered by the study. Participants are adults with obesity undergoing laparoscopic sleeve gastrectomy as part of their usual clinical care, performed by any of approximately eight upper gastrointestinal surgeons at the study site. The study does not assign or alter the operation; each surgeon operates according to their usual technique. The exposure of interest is the operating surgeon and the sleeve gastrectomy procedure itself. Standardised gastric anatomical measurements are made from the 3D-CT scans to quantify variation in stomach size and shape between different surgeons and within the same surgeon over time. No study treatment is assigned; all surgical and clinical care is delivered as usual care.