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E-learning module: interpreting X-rays. Flow diagram (printable). Multiple choice questionnaire [only visible once learning module completed] . This training tool is designed to help minimise the risk of feeding patients through a misplaced nasogastric tube.

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E-learning module:interpreting X-rays

Flow diagram (printable)

Multiple choice questionnaire

[only visible once learningmodule completed]

This training tool is designed to help minimise the risk of feeding patients through a misplaced nasogastric tube.

Please complete the learning module,at the end of which will be a multiple choice questionnaire which you must complete to gain your CME certificate.

This training tool has been developed by Dr Rob Law, Consultant GI Radiographer and Dr Joanne Bennett, Research Fellow, North Bristol NHS Trust.

It has been funded by Merck Serono

Reducing the risk of feeding through a misplaced nasogastric tube

reducing the risk of feeding through a misplaced nasogastric tube

Reducing the risk of feeding through a misplaced nasogastric tube

How to analyse check X-rays accuratelyto detect correct tube placement

  • The NPSA has published a list of ‘never events’ which are specific serious untoward incidents that can cause serious harm but should be avoidable if national guidance is followed(1)
  • One Never Event relates to: ‘Naso or orogastric tubes placed in the respiratory tract rather than the gastrointestinal tract and not detected prior to commencing feeding or other use’
  • The Quarterly Data Summary estimates 271,000 nasogastric tubes are purchased by the NHS annually(2)
  • Since the 2005 NPSA alert, the NRLS has received reports of a further 21 deaths and 79 cases of harm due to feeding into the lungs through misplaced nasogastric tubes. The main causal factor leading to harm was misinterpretation of X-rays. This was found in 45 incidents, 12 of which resulted in the death of the patient. This e-Learning module as been recommended in the March 2011 Alert(3)
  • Subjectively, from information gathered as part of an audit following a nasogastric feeding tube ‘never event’ at their Trust the authors concluded that formal instruction particularly to F1 and F2 medical practitioners regarding the interpretation of tube siting on check X-ray images is not wide spread
  • [last accessed 21.10.10]
  • National Patient Safety Agency. Incidents related to nasogastric tubes. August 2008. Quarterly Data Summary:9
  • National Patient Safety Agency Alert March 2011. [Last accessed 16.03.11]
contraindications to blind nasogastric tube insertion
Contraindications to blind nasogastrictube insertion

Fluoroscopically guided intubation should be considered in the following cases:

    • Base of skull fracture
    • Nasal injuries
    • Deviation of the nasal septum
    • Hiatus hernia and gastro-oesophageal reflux - if severe the risk of aspiration may be high
    • Functional problems such as loss of swallow or gag reflex
    • Oesophageal or gastric abnormalities e.g. stricture, pharangeal pouch, pharangeal compression, perforation, fistula - may require fluoroscopically guided intubation
    • Known oesophageal varices, ulceration or haemangioma (due to possibility of causing trauma)
    • Postoperative patients who have had upper GI surgery, with or without an anastamotic leak
  • Many contraindications are relative and a decision to place an NG tube in these patients and the mode of intubation may still be taken by more senior members of the team
  • In some of these situations use of fluoroscopic guidance can make intubation safer
using fine bore feeding tubes
Using fine bore feeding tubes
  • Acutely unwell patients are preferably fed through fine bore nasogastric tubes, provided they do not require gastric decompression with a larger Ryle’s tube
  • This is because fine bore tubes are more easily tolerated
    • Large bore tubes are associated with rhinitis, oesophageal reflux and strictures1
  • However, this tolerance comes at a price - patients may tolerate accidental intubation of the trachea and bronchi without obvious distress2
  • If the tube misplacement is not spotted, and feeding is commenced, the consequences can be serious, including3
    • Pneumothorax
    • Severe pneumonia
    • Empyema
    • Pulmonary haemorrhage
    • Death, depending on response to the above
  • Pearce CB, Duncan HD. Postgrad Med J 2002;78(918):198-204
  • de Aguilar-Nascimento JE, Kudsk KA. Curr Opin Clin Nutr Metab Care. 2007 May;10(3):291-6
  • Kawati R, Rubertsson S. Acta Anaesthesiol Scand 2005; 49(1):58-61
problems with fine bore nasogastric tube insertion a case example
Problems with fine bore nasogastric tube insertion – a case example
  • A seventy five year old woman with a past history of chronic obstructive airways disease and hiatus hernia was admitted under the care of the general surgeons with peritonitis secondary to a perforated sigmoid diverticula
  • She underwent a Hartmanns procedure with an end colostomy, but unfortunately her abdominal wound dehisced
  • She returned to theatre several times and was managed with an abdominalVAC dressing
  • She then developed pneumonia and was managed on the High DependencyUnit (HDU)
  • She had poor oral intake for a variety of reasons and her progress was slow
  • Therefore, after a review by the dieticians, it was decided during the evening ward round that she ought to commence nasogastric feeding
problems with fine bore nasogastric tube insertion a case example9
Problems with fine bore nasogastric tube insertion – a case example
  • Later on in that shift the nurse inserted the fine bore NG tube and asked the evening Senior House Officer (SHO) to order a portable X-ray to check its position
  • The X-ray was reviewed by the night HDU SHO at 0100
  • It was thought the X-ray was a little rotated, but that the position was probably slightly altered due to the hiatus hernia
  • Feeding was commenced
  • The patient’s respiratory function deteriorated overnight
  • When the patient was reviewed on the morning ward round, the X-ray was reviewed again and the team felt that the tube might be misplaced
  • The tube was removed and the patient treated for aspiration of feed with bronchial lavage (which confirmed feed in the bronchi) and adjustment of her antibiotic regime
problems with fine bore nasogastric tube insertion a case example10
Problems with fine bore nasogastric tube insertion – a case example
  • There are several factors within this scenario which contributed to the patient being fed via a misplaced tube
  • They fall into five main categories:
    • Human factors (e.g. difficulty interpreting X ray)
    • Equipment factors (e.g. use of less radiopaque tubes rather than ones that are completely radiopaque)
    • System factors (e.g. limited access to out-of-hours specialist radiology help)
    • Environmental factors (e.g. workload issues leading to delays)
    • Communication factors (e.g. documentation in the notes is often poor - when re-siting tubes it is important to know if there have been previous difficulties placing the tube)
incidence of tube misplacements
Incidence of tube misplacements
  • Difficult to determine due to limited number of studies in this area
  • Has been variously reported as being between 1.3% and 50%1
  • The National Patient Safety Agency (NPSA) reported 11 known deaths and 1 case of serious harm due to misplaced NG feeding tubes over a two year period(2003-2005)2
  • Led to the issue of a safety alert in 2005 on how to ensure feeding tubes areplaced correctly2
  • Since the release of the alert, there have been a further 79 reported cases of feeding through misplaced nasogastric tubes3

21 of these are thought to have directly contributedto the death of a patient

  • Ellett ML. Online J Knowl Synth Nurs 1997;4:5
  • National Patient Safety Agency (NPSA). Patient Safety Alert 05
  • Fayaz A. BMJ Careers;doi: 10.1136/bmj.c3850.
npsa never events

4. Misplaced naso or orogastric tube not detected prior to use

Definition: Naso or orogastric tube placed in the respiratory tract rather than the intestinal tract and not detected prior to commencing feeding or other use

Main care setting: All care settings

NPSA ‘never events’
  • Given the potential catastrophic consequences of tube misplacement, the NPSA designated feeding after NG tube misplacement as one of 8 ‘never events’1
  • This means there needs to be a system in place to help avoid the never eventtaking place
  • This training package is part of that safety system
  • [last accessed 10.08.10]
ask yourself

Are you 100% sure which patients need to have check X-rays and which you can confidently feed without?

Are you confident you have a reliable system in place for reviewing X-rays after NG tube placement?

Ask yourself
protocol for using ph strips to check ng tube position
Protocol for using pH strips to check NGtube position

pH testing

  • pH testing of aspirate is the initial method of choice for checking tube position
  • Ideally, use pH indicator strips that are CE marked, and have increments of measurement marked on
  • NICE guidelines state that if the aspirate has a pH of 5.5 or less using pH indicator strips, then feeding can be commenced as the tube is in the stomach
  • Litmus paper should never be used1

Checks should be carried out:

  • Following initial insertion
  • Before starting each feed or giving medication
    • As well as misplacement upon insertion, NG tubes that were inserted correctly initially can move out of the stomach at a later stage if the tube is dislodged
  • Once-daily, during continuous feed
  • Following vomiting, retching or coughing in case of displacement
  • If the tape around the nose is loose, or the visible tube appears longer than previously documented
  • MHRA medical device alert. 14 June 2004
when to proceed to check x ray
When to proceed to check X-ray?

Elevated pH

  • If pH is >5.5, repeat after one hour with nothing running through NG tube during this time
  • If pH is still >5.5 proceed to check position with X-ray
  • Reasons for an elevated pH in a correctly placed tube include use of antacid medication or feed raising the pH by diluting gastric secretions
    • (this is more common with continuous feed when checks are done during the period of feeding - in this case the feed should be switched off for one hour and the aspirate rechecked)
  • However, never assume that an elevated pH is acceptable whatever the cause
  • Always proceed to check X-ray

Difficulty obtaining aspirate

  • Turn patient onto side if possible
  • Try injecting 10-20ml of air into tube and wait for 15 minutes then try again


    • The Whoosh test is an old test, where air is injected into the tube and auscultation performed to listen for exit sound
    • The NPSA issued an alert in 2005, stating this test should no longer be used, as it is not an accurate method of checkingtube placement1
  • Advance tube 10-20cm and try again
  • If no aspirate is obtained in any of these situations – proceed to X-ray
  • National Patient Safety Agency (NPSA). Patient Safety Alert 05
interpretation of check x rays
Interpretation of check x-rays
  • The following slides will help you answer the important questions below
    • Can you interpret an image that is tilted or rotated?
    • Can you identify the carina?
    • Can you see the tube bisect the carina?
    • Can you identify the diaphragm and see the tube passing below it?
    • Which way does the tube deviate below the diaphragm?
    • Can you see the tip of the tube?
  • Please note, this training package has been developed using X-ray images that have been anonymised
  • Some of these images would be easier to interpret using the PACS viewing system due to the ability to change the density of the image - this function is not available on this training tracker
taking rotation into account
Taking rotation into account
  • This diagram illustrates the orientation of the clavicles, 1st ribs and thoracic spine in a non rotated chest X-ray

NG Tube central

Equal distance from clavicles

Non rotated film

taking rotation into account19
This X-ray demonstrates anon-rotated film

Look for the relationship of the clavicles, 1st ribs and spine

Taking rotation into account
taking rotation into account20
Taking rotation into account
  • This diagram illustrates how to identify rotation from the relationship of the clavicles, first ribs and spine. A film demonstrating this appears on the next slide.
    • The right shoulder is rotatedforward and the left shoulderis rotated away fromthe observer
    • This makes the thoracicspinal processesvisible to the right
    • The oesophagus lies slightly to the left
    • therefore the NG tube can be seenmore to the left of the vertebralbodies in a film rotated in this orientation
taking rotation into account21
This film demonstrates the features illustrated in the previous diagram. Look for:

Asymmetry in the clavicles and1st ribs

Spinous processes projecting tothe right

Note: this tube deviates to the left at the level of the carina and is likely to be in the base of the left lung

Feeding should not occur andthis tube should be removed




Taking rotation into account
identifying the carina
The carina (the point at which the trachea divides into the right and left main bronchi) usually lies at the level of the 4th or 5th thoracic vertebrae, although it can vary

Sometimes the angle of the carina can be very acute and in other patients the carina may be splayed wider apart. The carina can usually be seen on a standard chest X-ray

The image to the right is taken from a CT scan (in a patient without an NG tube) but it illustrates the x-ray appearance of the carina very clearly

When checking NG tube position the tube should be seen to pass into the area underneath the carina thereby "bisecting" it

This does not mean the tube has to pass precisely in the midline or divide the carina into equal halves

The diagram on the next slide illustrates this

Identifying the carina
identifying the carina23
Identifying the carina
  • This diagram illustrates how the carina appears to be bisected by the NG tube
identifying the carina25
This annotated diagram of the previous film highlights the carina

The tube does bisect the carina.It passes over the left main bronchus

Identifying the carina
identifying the carina26
This tube deviates at the level of the carina

The trachea lies slightly to the right of the spine as the film is rotated

The carina can be seen and the tube deviates to the right at this level –it does not bisect the carina

From review of this X-ray it appears thatthis tube is likely to be in the right lung base

In fact this patient has a right sided pneumothorax caused by forcing the NG tube against resistance through the lung parenchyma and into the pleural space

Feeding should not occur andthis tube should be removed



Identifying the carina
beyond the carina
Sometimes the carina can be a little unclear, particularly if there are other artefacts on X-rays that can cause confusion as in this example

If you are unsure whether the tube bisects the carina or deviates to either side follow the tube further down

Does it pass down the midline to the level of the diaphragm?

When passing below the diaphragm does it deviate immediately to the left?

If the answer to these questions is YES, the tube can be assumed to be in the stomach

In this film the carina is not particularly clear

It is also a little difficult to see the tube more inferiorly

However, it does appear to pass down the midline, below the diaphragm and then deviates to the left

It would be acceptable to feedthis patient nasogastrically

Beyond the carina
beyond the carina28
If the tube does not pass below the diaphragm feeding should not occur

It may be possible to advance the tube if it is felt to be in the oesophagus

In this situation aspirate may then be obtained meaning a further X-ray wouldbe unnecessary

Obviously sometimes tubes do not pass below the diaphragm due to being coiled higher up as in this example

In this situation the tube should be removed and resited

If there is a suspicion of any abnormal anatomy causing this (e.g. pharyngeal pouch) then fluoroscopic intubation should be considered

Beyond the carina
beyond the carina29
Beyond the carina
  • If the tip of the tube cannot be seen because it passes further below the diaphragm than can be seen on the X-ray, there are three options
    • It may be that the X-ray does not cover enough of the area below the diaphragm to see the tube and a further image is required
    • Sometimes the body of the stomach extends quite inferiorly in the abdominal cavity,but the duodenum is relatively fixed. Therefore, if the tube is in the duodenum it can usually be seen to loop back superiorly and to the right before turning inferiorly and tracking back towards the midline again
    • A tube that does not do this may well still be in the stomach. In this situation it is useful to use measurements
      • The length of NG tube to be inserted as a minimum is the same as the distance from the nasal septum to the tragus of the ear and then to the xiphisternum
      • If the tip of the tube cannot be seen but the length of tube in situ is this distance plus up to 15cm then it is acceptable to feed
interpreting check x rays flow chart system
Interpreting check X-rays– flow chart system
  • To increase accuracy in determining position of feeding tube, use a feeding tube that is fully radiopaque
  • In some cases, use of fluoroscopic guidance can make intubation safer
  • Remember, if in doubt regarding tube position for any reason, do not feed
  • The flow chart on the next slide demonstrates a system to increase accuracy when checking X-rays for correct NG tube position
misplaced tube
This tube appears to be below the level of the diaphragm therefore it could be incorrectly interpreted as being in the stomach


The base of the lungs extend much more inferiorly posteriorly

The tube deviates at the level ofthe carina

Misplaced tube


misplaced tube34
And on this x-ray of the same patient a lateral film demonstrates that the NG tube is indeed in the base of the right lungMisplaced tube
would you feed this patient
This NG tube bisects the carina, passes down the midline and below the diaphragm to the left and is in a suitable position for feeding

It would be acceptable to feed this patient nasogastrically

Would you feed this patient?
would you feed this patient36
This is another correctly sited tube

It bisects the carina, passes down the midline and below the diaphragm deviating initially to the left (although it then curves round to the right following the curve of the stomach as wouldbe expected)

It would be acceptable to feed this patient nasogastrically

Would you feed this patient?
would you feed this patient37
This tube is in the stomach, but only just and it would be advisable to advance it slightly prior to feeding

After advancing an aspirate might be more easily obtained, otherwise it could be reimaged

Would you feed this patient?
would you feed this patient38
This film is interesting. Sometimes NG tubes can have this appearance when they are in a hiatus hernia - particularly if it is incarcerated. This is uncommon

The tube is in a hiatus hernia.The deviation is quite low, near the diaphragm. However, any deviation in the chest – particularly if extreme like this – should raise the question:

Could this tube be in the lung?

Be very wary of attributing any deviation in the thorax to a hiatus hernia and get a senior opinion.

"If in doubt, take it out" is the bottom line

Would you feed this patient?
  • Not everyone needs a check X-ray
  • However if they do, it is important that the person interpreting it has a system of reading the X-ray in place as feeding down a misplaced tube can be catastrophic
  • Use the flowchart demonstrated earlier in these teaching slides to decrease the likelihood of misinterpreting an X-ray (insert link back to the flow chart)
test to gain cme points

Click here to go to test

Test to gain CME points
  • Now that you have completed this educational module, please complete the following test to gain your CME points
  • Within the test there are several images to review - sometimes you have to scroll down to see the bottom of the image, just beware of this as the bottom of the film sometimes contains very important information!