What does LES stand for?

This is known as lower esophageal sphincter or LES.

A transnasal esophageal pH catheter with a sensor placed 5 cm above the lower esophageal sphincter recorded reflux events and the acid clearance time for each event, while polysomnography recorded reflux-associated arousals and awakenings.

When the lower esophageal sphincter (LES) that separates the esophagus and the stomach fails to close properly, the stomach contents--a mix of food, enzymes, bile, and acid--backwash into the esophagus, often producing the sour taste and discomfort or outright pain of heartburn.

Findings on transnasal esophagoscopy were normal except for the presence of a widely patulous lower esophageal sphincter (LES) (figure).

and Shah (The Lahey Clinic) make this accessible enough for the general reader but specific enough to serve physicians, defining the disease and giving basic facts, and then going over symptoms and atypical manifestations, the role of hiatal hernias and lower esophageal sphincters, treatments such as lifestyle changes and diet, complications, medical evaluation, testing, related diseases, medications and surgical interventions.

One reason gastric reflux occurs in runners is the transient relaxation of the lower esophageal sphincter secondary to the swallowing of air.

Oftentimes, a malfunctioning valve between the stomach and esophagus--called the lower esophageal sphincter (LES)--is the cause.

The Enteryx procedure, which takes less than 30 minutes to perform, involves injecting a liquid compound into the lower esophageal sphincter during an endoscopy.