A combined surgical implement used in stomach reduction surgery and for serving as a template and testing integrity of a newly-formed gastric pouch is disclosed. A primary tube extending into a stomach of a patient carries a balloon inflatable to define a size and shape of a newly formed gastric pouch. Suction is applied through the tube to remove the stomach contents and deflate the stomach around the balloon, after which the gastric pouch is surgically formed. After surgical completion of the pouch, the pouch is tested by pressurizing and the pressure monitored. If a leak is present, the pressure falls and air bubbles in the saline solution surrounding the gastric pouch become evident, immediately indicating a leak in the newly-formed gastric pouch, which then may be repaired to seal the leak.
