Nasogastric tube
Measure nose–ear–xiphisternum, pass it with the patient swallowing, and confirm the position with pH under 5.5 or an X-ray before anything goes down it.
A 72-year-old woman with adhesional small-bowel obstruction is vomiting bile. Your registrar asks for a wide-bore NG tube on free drainage.
On the stroke ward, a 66-year-old man failed his swallow screen and needs a fine-bore feeding tube. After insertion, the aspirate pH is 6.5.
How do you place each tube, and can you start feeding the second patient?
- Choose the tubeWide-bore (Ryles, 12–18 Fr) for drainage. Fine-bore (8–10 Fr) for feeding.
- MeasureNose to earlobe to xiphisternum (NEX). Note the mark.
- PositionSitting upright, chin slightly down.
- InsertLubricated, along the floor of the nose, backwards not upwards. Ask the patient to swallow sips of water as it passes.
- Coughing, distress or voice changeWithdraw. It may be in the airway.
- Confirm before feedingAspirate pH 5.5 or below. If not, chest X-ray.
- Secure and documentMark at the nostril, tape, record length.
- Coughing, choking or desaturation during insertion
- Aspirate pH above 5.5 and X-ray unclear
- Nosebleed that doesn't stop
- Suspected base-of-skull fracture
- Tube in the lung (feeding into it can kill)
- Coiling in the mouth
- Displacement after vomiting or coughing
- Refeeding syndrome when feeding starts
- Pressure injury to the nostril
| Feeding tube confirmation | Aspirate pH 5.5 or below on pH paper |
| X-ray criteria | Tube down the midline, bisects the carina, crosses the diaphragm, tip below the left hemidiaphragm |
| Fine-bore | 8–10 Fr for feeding |
| Wide-bore | 12–18 Fr for drainage |
| Insertion length | Nose to earlobe to xiphisternum, plus about 10 cm for drainage tubes |
Check every dose against a current drug reference and your hospital protocol.
On this page
Indications
- Drainage: bowel obstruction, ileus, severe vomiting, gastric decompression in ventilated patients.
- Feeding and medicines: unsafe swallow (stroke, reduced consciousness), head and neck cancer, ICU.
Contraindications and cautions
- Base-of-skull fracture or major facial trauma: never nasal; use the oral route.
- Recent nasal, oesophageal or gastric surgery: discuss with the surgeons.
- Oesophageal varices or stricture: caution, senior input.
- Severe coagulopathy.
Technique
- Explain and agree a stop signalA raised hand.
- MeasureNose to earlobe to xiphisternum. Mark the tube.
- PositionUpright, head neutral or slightly flexed. Check the more open nostril.
- Lubricate and insertWater-based gel. Aim straight back along the floor of the nose, not upwards.
- SwallowAt the back of the throat, ask the patient to swallow sips of water (if safe) or dry swallow, and advance with each swallow.
- Stop ifCoughing, choking, voice change, desaturation: withdraw and retry.
- Advance to the mark, then confirmAspirate and test pH, or X-ray.
Confirming position
Gastric. Safe to feed. Document.
Wait, reposition patient, try again. Still not: chest X-ray.
Do not use. Reposition or reinsert.
Never use the "whoosh" test (air with a stethoscope), litmus paper or the appearance of the aspirate to confirm placement. They are unreliable.
On X-ray: the tube runs down the midline, bisects the carina, crosses the diaphragm in the midline, and the tip is clearly below the left hemidiaphragm.
Acid-suppressing drugs (PPIs, H₂ blockers) can raise gastric pH above 5.5. If the aspirate is above 5.5 in a patient on these, use X-ray.
Tips when it won't pass
- Cool the tube in the fridge for a stiffer tip (wide-bore).
- Try the other nostril.
- Flex the neck more as it reaches the throat.
- Sips of water through a straw.
- Don't push against resistance.
After insertion
- Secure with tape or a nasal bridle (if the tube keeps coming out).
- Document the length at the nostril.
- Check position before every feed, medicine, or after vomiting, coughing or suspected displacement.
- Flush with water before and after medicines and feeds.
- Malnourished patient starting feeds: check phosphate, potassium and magnesium (refeeding syndrome).
Common mistakes
- Feeding through a tube that hasn't been confirmed.
- Using the whoosh test.
- Pushing a nasal tube in a patient with a base-of-skull fracture.
- Aiming upwards (the nose floor runs straight back).
- Not checking position after vomiting.
- Forgetting refeeding risk in a starved patient.
Frequently asked questions
How do you check NG tube position?
Test aspirate pH: 5.5 or below confirms gastric placement. If not, get a chest X-ray.
What pH confirms NG tube placement?
5.5 or below.
How do you measure the length of an NG tube?
From the nose to the earlobe to the xiphisternum.
When should an NG tube not be passed through the nose?
In suspected base-of-skull fracture or major facial trauma. Use the mouth instead.
Test yourself
Exam-style questions on this guide, from our two question banks. Choose an answer to see why each option is right or wrong.
1. After NG tube insertion, the aspirate pH is 6.5. What should be done?
Answer: Don't feed. pH 5.5 or below confirms gastric placement; otherwise X-ray.
- Put the end in water: Unreliable.
- Feed slowly: Unsafe.
- Start feeding: Not confirmed in the stomach.
- Whoosh test: Unreliable.
2. How is the NG tube length estimated?
Answer: Nose-ear-xiphisternum. NEX measurement.
- Ear to sternum: No.
- Nose to umbilicus: No.
- Fixed 40 cm: No.
- Mouth to umbilicus: No.
3. In which patient is a nasal tube contraindicated?
Answer: Basal skull fracture. Risk of intracranial placement; use the oral route.
- Bowel obstruction: Indication.
- Elderly patient: Not a contraindication.
- Stroke with dysphagia: Common indication.
- Post-op ileus: Indication.
4. A swallowed coin in a child most commonly lodges at which site?
Answer: Cricopharyngeus (C6). The oesophagus has four constrictions: cricopharyngeus (C6, 15 cm from incisors — narrowest and commonest site for foreign bodies), aortic arch (T4, 22.5 cm), left main bronchus (T5, 27.5 cm) and diaphragm (T10, 40 cm). A coin in the oesophagus appears face-on (round) on an AP chest X-ray; in the trachea it appears edge-on. Button batteries need urgent removal.
- Where the left bronchus crosses: Third constriction; less common.
- Lower oesophageal sphincter: Fourth constriction.
- Pylorus: Most objects that reach the stomach pass.
- Ileocaecal valve: Rare site.
5. A 50-year-old man has a new right middle-ear effusion that does not clear. Endoscopy shows a mass in the right nasopharynx infiltrating the muscles of the soft palate. What is the mechanism of the effusion?
Answer: Eustachian tube blocked by tumour. The Eustachian tube opens in the lateral nasopharynx, and the tensor and levator veli palatini open and support it during swallowing. A nasopharyngeal tumour blocks the opening and paralyses these muscles, so the middle ear cannot be ventilated. Air is absorbed, negative pressure develops and a serous effusion forms. A new unilateral effusion in an adult should prompt examination of the nasopharynx.
- Tumour spread into the middle ear: Direct spread into the ear is rare; the fluid is a serous effusion.
- Infection along the facial nerve: The facial nerve is not the route; the ear is not infected.
- Raised intracranial pressure: Raised pressure does not cause a unilateral ear effusion.
- Venous congestion of the mastoid: Mastoid fluid here follows tube obstruction, not venous congestion.