Return of gastric or duodenal contents into the esophagus from an incompetent or poorly developed esophageal sphincter

Also called GERD

Lower esophageal sphincter (LES) function prevents gastric contents from backing up into the esophagus.

LES normally creates pressure, closing the lower end of the esophagus, but relaxing after each swallow to allow food into the stomach.

Reflux occurs with deficient LES pressure or when pressure within the stomach exceeds LES pressure.

Predisposing factors: administration of agents decreasing LES pressure, hiatal hernia with incompetent sphincter, long-term nasogastric intubation, prematurity

Vomiting, possibly related to feedings, positioning, and activity level immediately after feedings (in infants)

Occurring most immediately after eating

Typically affecting infants but also seen in young children with spastic cerebral palsy due to decreased muscle tone