NG tube position on X‑ray

Written by the X-Ray Atlas editorial team from the sources listed below · Medical review pending · Updated 24 October 2026 · Level: Beginner

A nasogastric (NG) tube is passed blind through the nose, so nobody can see where it goes. Most end up in the stomach, but some pass into the trachea and down a bronchus, sometimes as far as the pleura, with no obvious distress, especially in sedated, ventilated or neurologically impaired patients. Putting feed, fluid or medication down a tube that sits in the airway can kill. In England, this is listed as a Never Event: a wholly preventable incident that should not happen if national guidance is followed. This page explains where the X-ray fits in, the four radiographic criteria from national guidance, the dangerous patterns, and when to stop and escalate.

1. Why NG tube position matters

NG tubes (and orogastric tubes, passed through the mouth) are used for feeding, giving medication, and draining the stomach. The harm comes almost entirely from using a tube for feed, flush or medication when its tip is not in the stomach. Fluid in the airway or pleura causes aspiration pneumonitis, pneumonia, empyema and death. A tube can also perforate the pharynx or oesophagus, or cause a pneumothorax if the tip passes through the lung into the pleural space.

National patient safety alerts in England have repeatedly addressed this risk. The National Patient Safety Agency (NPSA) alert of 2011 (PSA002) set out the bedside and radiographic checks. A further alert from NHS Improvement in 2016 (NHS/PSA/RE/2016/006) reported that harm was still occurring, and highlighted that the commonest causes were X-rays that were misinterpreted, films of the wrong patient or the wrong time being reviewed, and tubes being used without any position check being documented. In other words, reading the film properly is the patient-safety intervention.

2. pH first: where the X‑ray fits

In UK practice the X-ray is not usually the first check. The national guidance puts the bedside pH test first:

1. After insertion, aspirate from the tube and test it on a CE-marked pH indicator strip intended for human gastric aspirate.
2. A pH of 5.5 or below (the commonly quoted range is 1 to 5.5) supports gastric placement, and in most adult policies the tube may then be used after the result is documented.
3. An X-ray is requested when no aspirate can be obtained, when the pH is above 5.5, or where local policy requires one routinely. Many policies require an X-ray first-line in groups where the pH test is less reliable or the consequences of error are greater: for example intensive care patients, people on acid-suppressing drugs, and those with an impaired swallow or reduced consciousness.

Acid-suppressing drugs (proton pump inhibitors, H2 antagonists) and continuous feeding can raise gastric pH above 5.5, so a high pH does not prove the tube is in the wrong place. It means the bedside test has not confirmed position, and another method is needed.

3. Getting a film that answers the question

A film that cannot show the whole tube cannot confirm it. Before interpreting anything:

• Right patient, right film, right time. Check the name and identifier, and check that the film was taken after the current tube was inserted. Reviewing an old film from a previous tube is a recognised cause of Never Events.
• The request should say why. The request should state that the purpose of the film is to confirm NG tube position, so the radiographer can include the whole course and the person reporting knows the question.
• Coverage. The film should show the tube from the neck to below the left hemidiaphragm. A film that stops at the diaphragm cannot show the tip.
• Exposure. Fine-bore tubes are thin and faintly radiopaque. The film needs enough penetration for the tube to be seen through the heart and mediastinum. Enhancing the image (windowing) on the PACS workstation helps.
• Guidewire. Some fine-bore tubes are X-rayed with the guidewire in place to make them easier to see, others after it is removed. This depends on the device and local policy. Never reinsert a guidewire into a tube that is in the patient.

Also check for other devices. On ICU films an endotracheal tube, central line, ECG leads and temperature probes can all be confused with an NG tube. Trace each line from end to end before deciding which one is the NG tube.

4. The four radiographic criteria

The NPSA 2011 alert, supported by the Royal College of Radiologists, describes four features of a correctly placed tube on a chest X-ray. All four must be present.

Here is what each criterion means on the film, and why it is there.

1. Midline, avoiding the bronchi

The oesophagus runs down behind the trachea and roughly in the midline, slightly to the left in its lower part. A tube in the oesophagus therefore stays close to the spine and does not follow the branching shape of the airways. A tube that veers off to one side above the diaphragm, or follows the line of a main or lobar bronchus, is in the airway until proven otherwise.

2. Bisects the carina or the bronchi

Find the carina, where the trachea divides. An oesophageal tube passes straight down through, or very close to, the angle between the main bronchi, crossing the carina rather than turning into one bronchus. A tube that enters the right main bronchus and continues into the right lower lobe is the classic misplacement.

3. Crosses the diaphragm in the midline

The oesophagus passes through the diaphragmatic hiatus at around the level of T10, a little to the left of the midline. The tube should be seen crossing the diaphragm there and turning towards the left upper quadrant. A tube that crosses the diaphragm far laterally, or does not cross it at all, is not in the oesophagus.

4. Tip clearly visible below the left hemidiaphragm

The tip should project over the gastric shadow, below the left hemidiaphragm. "Clearly visible" matters: if the tip cannot be seen, or could be above the diaphragm, criterion 4 is not met. A tube can pass into the lower lobe bronchus and project below the dome of the diaphragm on a frontal film, because the posterior lung bases extend down behind the dome. This is why the tip alone is not enough, and the whole course must be traced.

5. Where the tip should be

For feeding, the tip should be in the stomach, and far enough beyond the gastro-oesophageal junction (GOJ) that the side holes are in the stomach too. A commonly taught target is at least 10 cm beyond the GOJ. A tip just below the diaphragm may leave side holes in the distal oesophagus, which risks reflux and aspiration of feed.

• Tip in the stomach, well below the GOJ: consistent with gastric placement if all four criteria are met.
• Tip in the distal oesophagus, or at the hiatus: too short. Do not use. Usually advance and re-check per policy.
• Tip in the duodenum: beyond the stomach. Appropriate only for a nasoduodenal or nasojejunal tube intended to go there.
• Hiatus hernia: part of the stomach lies above the diaphragm, and the tube may turn back up into it. This makes the criteria hard to apply and is a reason for senior or radiologist review, not for guessing.

6. Dangerous patterns

Pattern	What you see	Risk
Bronchial placement	The tube leaves the midline at the carina and follows a main bronchus, most often the right and into the right lower lobe.	Feed into the lung; aspiration pneumonia.
Pleural placement	The tube passes beyond the lung edge or curls in the costophrenic angle. There may be a new pneumothorax.	Pneumothorax, empyema if fed.
Coiled in the pharynx or oesophagus	Loops of tube in the neck or mediastinum, and the tip never reaches the abdomen.	Aspiration, oesophageal injury.
Tip in the distal oesophagus	The tube follows the midline correctly but ends at or above the diaphragm.	Reflux and aspiration of feed.
Tip not visible	The film is cropped, under-exposed or the tube fades out.	Unknown position: treat as unconfirmed.

A tube can also take an unusual course in patients with altered anatomy: oesophagectomy, gastric pull-up, a large hiatus hernia, or severe kyphoscoliosis. These films should be reviewed by someone experienced, and the patient's surgical history should be known.

7. Pitfalls

• Reading the wrong film. The most avoidable error. Check the date and time against the insertion time documented in the notes.
• Confusing tubes and lines. ECG leads, a temperature probe or a central line can overlie the midline. Trace from the nose or neck downward.
• Over-reliance on the tip. As above, a tip that projects below the diaphragm does not confirm position on its own.
• Accepting a poor film. If the tube cannot be seen along its full length, the film cannot confirm it. Repeat or escalate.
• Assuming a tube stays put. Tubes migrate with coughing, vomiting, retching and patient handling. Most policies require re-checking (usually by pH, and by checking the external length mark) before each use, and a new check after any event that could have moved the tube.
• Interpreting a report that doesn't answer the question. A formal chest report that comments on the lungs but not the tube is not a confirmation of position.

8. When to escalate: a decision flow

This is a generic teaching flow. Your local policy takes precedence in every detail.

Documentation matters as much as the interpretation. Most policies require the person confirming position to record who reviewed the film, which film (date and time), that all four criteria were met, and the external length mark of the tube at the nostril.

Red flags: act now

What to focus on, by role

Role	Priorities
Medical student	Learn the four criteria word for word and the reason for each. Practise tracing tubes on ICU films, and learn why the bedside "whoosh" test is not used.
Nurse	The pH-first approach, documentation, and your trust's rules on who may confirm position from an X-ray. Never feed while waiting for a film, and re-check before each use.
Junior doctor	You may be asked to "check the NG film" out of hours. Only do so if you have been trained and are authorised by local policy. Use all four criteria, document them, and ask for help when in doubt rather than giving a qualified yes.
Radiographer	Include the whole tube from neck to below the left hemidiaphragm with adequate penetration. Many departments ask radiographers to flag an obvious bronchial tube immediately.
Advanced / FRCR	Altered anatomy (oesophagectomy, hiatus hernia), wording reports so the four criteria are explicitly addressed, and departmental audit of NG reporting.

Related pages: how to read a chest X-ray, ETT position, central lines and PICCs, and the glossary.

Practise on lines and tubes films →

References

1. National Patient Safety Agency. Patient Safety Alert NPSA/2011/PSA002: Reducing the harm caused by misplaced nasogastric feeding tubes in adults, children and infants. 2011. england.nhs.uk
2. NHS Improvement. Patient Safety Alert NHS/PSA/RE/2016/006: Nasogastric tube misplacement: continuing risk of death and severe harm. 2016. england.nhs.uk
3. Royal College of Radiologists. Audit: Reducing the harm caused by misplaced nasogastric feeding tubes in adults, children and infants. 2011. rcr.ac.uk
4. NHS England. Never Events policy and framework, and Never Events list. england.nhs.uk
5. Radiology Masterclass. Chest X-ray: NG tube anatomy. radiologymasterclass.co.uk

For education only. Not a substitute for a formal report, senior review or your local policy. Never use this page to make decisions about a real patient.