Motility and Functional Gastrointestinal Disorders Center phMotility Study

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What is a pH motility study?

  • A pH motility study is a procedure in which a small flexible tube is placed into the nose and passed into the esophagus (food pipe).
  •  It is used to find out how well your child's esophagus is working by measuring the pressure and coordination of the esophageal muscles, and to find out if acid from the stomach is coming up into the esophagus.

What happens before the pH motility study?

  • Your child must have an empty stomach for the procedure. No solid food should be eaten for eight hours before the procedure. A member of the gastroenterology or endoscopy staff will tell you how long before the procedure your child must stop eating and drinking.
  • It is very important that your child not take any medicines that reduce the amount of acid made in the stomach for at least 48 hours before the test. If your child regularly takes acid reducing medications, please talk with your doctor a few days before the test to plan accordingly.

What happens during the pH motility study

  • Your child will need to sit upright on the bed for the procedure. If your child is given medicine to make him/her relaxed for the procedure, he or she will wear a heart and oxygen monitor.
  • A flexible tube will be inserted into the nose and passed into the esophagus.The tube is attached to a computer that measures the pressure and coordination of the esophageal muscles. Depending on your child's age, he or she may be given a numbing medicine inside his or her nose.
  • The tube will slowly be repositioned in the esophagus. Your child will be asked to swallow sips of water, and measurements will be taken at each level of the esophagus. This motility portion of the procedure usually takes about 30 minutes.
  • The tube will then be taped in place for the pH portion of the study, which may last 18 to 24 hours. Occasionally an x-ray is needed to verify the placement of the tube. This portion of the study determines if acid is coming from the stomach into the esophagus. The end of the tube is attached to a small recording machine. This recorder has a belt that may be buckled around your child's waist or over a shoulder. 
  • Younger patients are usually admitted to the hospital after the tube is inserted. Occasionally, older children can go home with the tube in place.
  • You will be asked to write down what your child is doing while the tube is in place, such as eating, sleeping, walking and coughing. 
  • Your child's physician or nurse will explain exactly what needs to be written down to help with the study. The doctor will use the diary to compare the computer reading with your child's activity.
  • The tube will be removed the next day by a member of the gastroenterology staff. Removing the tube takes less than a minute and does not hurt. Some children cough or sneeze. 

How will we be informed of the results?

Your child's doctor will speak with you as soon as the motility portion of the procedure is done. After the tube is removed, the information in the recorder is put into a computer. A gastroenterology doctor will interpret the results and give them to your child's primary doctor. Call your child's primary doctor one week after the study for the results.

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Boston Children's Hospital 300 Longwood Avenue, Boston, MA 02115 617-355-6000 | 800-355-7944