Article updated and reviewed by Daniel A. Rauch, MD, FAAP, Associate Professor of Clinical Pediatrics, Associate Residency Program Director and Director of Pediatric Hospitalist Service, New York University on May 17, 2005.

The backwash of stomach contents into the esophagus, commonly called reflux, occurs when the lower esophageal sphincter (LES) is very weak or, more commonly, when it inappropriately relaxes. Gastroesophageal reflux (GER), often manifested as regurgitation (spitting up or...