Houston Methodist. Leading Medicine.
Houston Methodist. Leading Medicine

24-Hour pH Probe

Testing Information: 24-Hour pH Probe (Nasal Catheter)

What is 24-Hour pH Probe (Nasal Catheter)?

The 24 Hour pH Probe is a test is done to evaluate the extent of acid reflux, or backflow, from the stomach into the esophagus. An esophageal motility test is first done to determine correct placement of the pH probe.


Some patients may experience throat discomfort and nosebleed.

What to do the night before the procedure

Do not eat or drink anything after midnight prior to your test.

Preparing for the procedure

Do not smoke the day of your test. Follow your physician’s instructions regarding discontinuing medications. Drugs such as proton pump inhibitors (Aciphex®, Prilosec®, Prevacid®, Protonix®, Nexium®) or H2 blockers (Axid®, Pepcid®, Tagamet®, Zantac®) may affect test results. It is recommended that these drugs be withheld 7 days prior to the test. Your physician will instruct you whether to take these medications or withhold them. If your physician has instructed you to withhold the above medications and you are experiencing discomfort you may take antacids such as; Rolaids®, Tums® or Mylanta®. If you are an asthma patient bring your inhaler.

During the procedure

An esophageal motility test is first done to determine correct placement of the pH probe. This involves inserting a very small catheter into the nostril and advancing it into the stomach. The catheter is withdrawn slowly as the patient is given sips of water. This portion of the test takes 20 to 25 minutes and the motility catheter is removed at the completion.

Next, a different catheter, called a pH probe, is inserted into the nostril and advanced into the esophagus. The pH probe will remain in place for 24 hours and is connected to a small recorder that you will carry on a strap over your shoulder. You will be asked to return the following day to have the probe removed. You will be given written instructions regarding diet, medications, smoking and bathing. You will also be provided a diary sheet to record selected events throughout the 24 hour period.

While the pH probe is in place, some patients experience irritation in the throat, which can be relieved by taking sips of water. Do not use throat lozenges since they may change the results of the test. Some patients report more difficulty sleeping than usual because of their awareness of the probe. Although the probe does not prevent eating or drinking, some patients find these activities somewhat uncomfortable. This discomfort disappears as patients become adjusted to the probe being in place.

After the procedure

You may drive yourself home after the procedure.