After numbing one nostril with a special lubricant, a flexible plastic tube about 1/8 inch in diameter is passed through the nostril, down the
back of the throat, and into the esophagus and stomach as the patient swallows. Once the tube is in place, patients talk and breathe
normally. Inside the esophagus, the tube measures the pressures generated by the esophageal muscle at rest and during swallows. The
procedure takes 20 to 30 minutes to perform.
When food is swallowed, a wave of muscular contractions propels the food down the esophagus and into the stomach. At the upper and
lower ends of the esophagus are two short areas of specialized muscle called the upper and lower esophageal sphincters. At rest (when
there are no swallows) the muscle of the sphincters is active and generates pressure that prevents anything from passing through them.
As a result, material within the esophagus cannot back up into the throat, and stomach acid and contents cannot back up into the
esophagus. When a swallow occurs, the sphincters relax briefly to allow food to pass.
Limitations of Esophageal Manometry
In certain cases, manometry may not identify the esophageal abnormality that is causing a patient's problem. In some patients with GERD,
for example, the cause of reflux may be that the lower sphincter relaxes only occasionally and for prolonged periods (minutes rather than
seconds.) Infrequent relaxations may be missed during the short period of the test.
Also, if a patient has infrequent episodes of chest pain due to esophageal spasm, (such as every few days or weeks), a spasm may not
occur during the manometry test.
Manometry Side Effects
Some patients find manometry uncomfortable but most say it is only minimally painful because the nostril through which the tube is
inserted is numbed. Side-effects of manometry are minor and include mild sore throat, nose-bleed, and (rarely) sinus problems. During
insertion, the tube occasionally may enter the larynx (voice box) and cause choking. When this happens, the tube is rapidly removed.