A particular type of gastric bypass surgery called Roux-en-Y gastric bypass (RYGB) can rapidly lead to the development of kidney stones — small, pebble-like deposits in the kidneys that can cause severe pain.

These stones develop in patients within only a few months following the procedure, rather than several months to years, as had been previously thought.

RYGB is the most commonly performed surgical intervention for morbid obesity. During the procedure, a small pouch is created by stapling part of the stomach together, limiting the amount of food a patient can eat. Then, a Y-shaped section of the small intestine is attached to the pouch to allow food to bypass the first part of the intestines, reducing calorie and nutrient absorption.