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How to check the position of an NG tube


1. Aspiration of gastric contents

  • Before removing the guide wire, aspirate from the NG tube and check for gastric pH
    • a pH of between 0 and 5 confirms placement of NG tube
    • If pH confirmed, remove guide wire and tape tube in place
  • If unable to aspirate from the NG tube, do not remove guide wire, tape wire in place
  • If unable to confirm placement with pH test, request chest radiograph
    • It is important not to start using the tube for feeding purposes until placement is confirmed. Patients on protein pump inhibitor medication or who have undergone previous gastric surgery should always receive a chest radiograph to confirm placement.


2. Check an NG tube position on chest X-Ray

The flow diagram below takes you through how to check the position of a of an NG tube on CXR

How to check NG tube position on X-Ray - flow

The normal CXR should look like the XR below

Correct NG tube positioning


Incorrect placement includes CXRs below

Incorrect NG tube placement


Incorrect NG tube placement - in lung via right main bronchus


Management of an NG tube after insertion:

  • In the case of NG placement for drainage of stomach contents, the volume and character of the contents should be monitored regularly and documented.
    • A standard management protocol is free drainage into bile bag with 4 hourly aspirations.
  • In the case of NG placement for feeding, the patient’s nutritional and hydration status should be monitored daily, with particular care to monitor electrolytes including potassium, calcium and usually magnesium as well as albumin. This is to aid the dietician in assessing the ongoing needs of the patient and the success or failure of this feeding modality.
  • The need for the NG tube should be reassessed regularly and it should be removed as soon as possible, either when symptoms resolve, when clinical decisions render it defunct (for example the decision for operative intervention for bowel obstruction instead of “drip and suck”) or after 4 weeks, as per NICE guidelines.


Click here for medical student OSCE and PACES questions about nasogastric (NG) tube placement