pH Impedance Study | Children's National Hospital

Measuring the pH and impedance in the esophagus helps determine if acid or stomach contents are coming back up the esophagus. A pH impedance study is usually done when gastroesophageal reflux (GER) is suspected. It can also be used to determine how effective treatment is while taking antacids. The study might help explain nighttime cough, hoarseness or other complaints.

How is the pH impedance study performed?

A thin plastic tube with sensors is placed into one nostril and advanced into the esophagus. When the tube is placed, it may cause gagging, sneezing or make your eyes water. A chest X-ray will check the position of the end of the probe. The probe is connected to a recording box that your child can carry with them during the 24-hour study. This box has buttons to record events such as abdominal pain and reflux. These instructions will be provided and reviewed by the GI nurse when the probe is placed.

What is allowed during the pH impedance study?

Your child should continue with regular activities. A diary will be given to you to record your child’s symptoms (crying, coughing, pain, reflux, etc.) during the study. You will also be asked to record meal times, sleeping and any other information you would like to share with your provider. This information helps us determine if reflux is responsible for your child’s symptoms. During the study, your child should not take a bath or shower, chew gum or eat hard candy, and carbonated drinks should be avoided.

What happens after the pH impedance study?

After 24-hours, the tube can be removed from your child’s nose. You can remove it at home or you can come back to the hospital and have the tube removed. Once removed, the tube can be thrown away. The recording box and your child’s event diary need to be returned the next day to the registration desk where you checked in for the procedure. If your provider stopped any antacid medications for the study, they can be restarted once the study is over. The information stored on the recorder is then analyzed. Reflux is determined by the impedance and pH analysis. A score can be calculated to help determine how abnormal the pH probe study is. Your child’s physician will contact you once the study results are available.

Instructions for the pH Impedance Study

This is a NON-SEDATED procedure.
Please arrive to the second floor OR registration one hour prior to the study time on the day of study.
Your child should not have anything to eat for four hours prior to the study.
Your child can have clear liquid up to two hours before the study (juice, clear broth, popsicles, jello), including breast milk.
The nurse will review all instructions with you at the time of the study.
Your provider may have your child stop antacid medications for the study. Please check with your provider about stopping medications prior to the study.