Nasogastric Tube Placement Check: pH Testing, X-Ray and Never-Event Safety Rules

Feeding or giving medicines through a nasogastric (NG) tube that has gone into the lungs can cause pneumonia and death. In England, feeding through a misplaced NG tube is classed as a Never Event, a serious incident that should never happen if safety guidance is followed.

Before insertion

• Check the indication and any reasons not to pass a tube nasally, such as a suspected base of skull fracture or recent nasal surgery
• Explain the procedure and gain consent where possible
• Measure the length using NEX: from the tip of the Nose to the Earlobe, then down to the Xiphisternum, and note the mark on the tube
• Use a fine-bore tube designed for feeding, with ENFit or similar connectors that cannot fit IV lines

First-line check: aspirate pH

1. Draw back a small amount of aspirate with a 50–60 mL enteral syringe.
2. Test it on a CE-marked pH indicator strip intended for human aspirate.
3. A pH of 5.5 or below indicates gastric placement, and feeding can start.
4. Record the pH, the external length mark and the time.

If no aspirate comes back, try turning the patient onto their left side, injecting 10–20 mL of air (for adults, if your policy allows), waiting 15–30 minutes, or advancing or withdrawing the tube slightly, and then aspirate again.

If the pH is above 5.5 or there is no aspirate

Do not feed. Placement must be confirmed by chest X-ray, interpreted and documented by a person trained and competent to do so. Patients on acid-suppressing medicines such as PPIs can have a higher gastric pH, which is one reason why some need X-ray confirmation.

Methods you must never use

• The “whoosh test” (listening for air injected into the stomach)
• Litmus paper
• Looking at the appearance of the aspirate
• Absence of coughing or breathing difficulty
• Bubbling when the end is placed in water

These methods are unreliable and have been linked to deaths.

When to recheck placement

• Before the first feed after insertion
• Before every feed, flush or medicine
• At least once a day during continuous feeding
• After vomiting, retching or coughing fits
• If the external length mark has moved, the tube looks displaced, or the patient becomes breathless

Giving medicines via an NG tube

• Ask a pharmacist which forms are suitable; liquids or dispersible tablets are usually preferred
• Never crush modified-release, enteric-coated or cytotoxic medicines
• Flush with water before, between and after each medicine, as per local policy
• Give each medicine separately

Sources: NHS England (formerly NHS Improvement), Patient safety alert: Nasogastric tube misplacement – continuing risk of death and severe harm (2016) and Never Events list; British Association for Parenteral and Enteral Nutrition (BAPEN) guidance.