24 Hour pH Monitor

24 Hour pH Monitor (Esophageal pH)

A 24 hour pH Monitor test measures how often stomach acid flows into the lower esophagus and the degree of acidity during a 24 hour period.


A small thin probe at the end of a long tube is the equipment used for measuring esophageal pH. This probe can measure the acidity of the patient's stomach. The probe is gently inserted through the nose down to the end of the esophagus. A portable recorder is attached and is carried at the waist. The acidity in the lower esophagus is recorded on a paper tape during a 24 hour period. When the patient experiences reflux or other symptoms he or she presses a button on the recorder to mark the time. This will show how the acidity level relates to the patient's activity. After the probe is removed the recording is analyzed and a full report is sent back to the physician.

Reason for the Exam

Symptoms such as heartburn, difficulty swallowing food or liquid and chest pain are most common reasons for performing a 24 Hour pH Monitor. The measurement of pH may be helpful in determining the success of treatment for acid reflux. Therefore, this procedure is often done before and after medical and surgical treatment of acid reflux disease.


The patient should fast 8 hours before the procedure, This includes food and liquids. Patients need to review all medications they are taking with their physician so they can be advised which they should and should not take before the test. Many medications need to be stopped 48 hours before the test. These include:

  • Caffiene (coffee, tea, cola, chocolate)
  • Alcohol
  • Propulsid
  • Reglan
  • Urecholine
  • Erythromycin
  • Nitroglycerine
  • Calcium Channel Blockers (Procardia, Adalat, Calan, Cardizem, etc.)
  • Beta Blockers (Corgard, Inderal, Lopressor, etc.)
  • Donnatol
  • Librax
  • Levsin
  • Tagasmet
  • Zantac
  • Pepcid
  • Axid
  • Prilosec
  • Prevacid

Again, please be sure to review all medications with your physician prior to your appointment as there may be other medicines that need to be stopped that are not listed above.

The Procedure

The procedure takes 10 to 15 minutes from start to finish. While the patient is seated or lying on their side a thin soft tube is gently inserted through the nose. The patient is asked to swallow so the tip of the tube enters the esophagus and the technician quickly passes the tube to the desired level. There may be some slight gagging at this point but it is easily controlled. The tubing is then attached to the recorder and attached to the waist. The patient is discharged to his or her regular diet and activities.

Benefits and Alternatives

The clear documentation of the degree and duration of the acidity in the esophagus is the primary benefit of this exam. A specific treatment program can be outlined or reassurance given if the exam is normal.

Nothing really takes the place of the 24 Hour pH Measurement, but often this exam is performed in association with a pressure recording of the esophagus called an Esophageal Manometry.

Side Effects and Complications

Generally there are no serious complications associated with the Esophageal pH test.


The 24 hour pH test is a valuable tool used to determine the severity of acid reflux into the esophagus. With this information the physician can usually develop effective treatment for most patients who have acid disorders in the lower esophagus.