Definition and symptoms of belching
Belching is due to sudden expulsion of previously ingested air, unless precipitated by the ingestion of carbonated drinks. Gas is not produced within the normal stomach. Belching disorder is defined as at least 6 months of bothersome belching that occurs on more than 3 days per weekRome Foundation Inc., 2016.
Supragastric belching occurs when gas is drawn into the oesophagus by glottic closure and reduction in thoracic pressure, or pumped by the pharynx into the oesophagus, and immediately expelled, usually without reaching the stomach. A series of belches may go on for several minutes and can be severe enough to interfere with speech.
Gastric belching occurs when the stomach is distended with gas (eg due to aerophagia—the habitual swallowing of air) which is then released. Occasionally gas travels through the gastrointestinal tract, resulting in abdominal distension, borborygmi and excessive flatus.