Ultrasound Guided Peripheral Vascular Access

Cite this article as:
Trent Calcutt. Ultrasound Guided Peripheral Vascular Access, Don't Forget the Bubbles, 2021. Available at:

One of my favourite things in paediatrics is the expanding role of ultrasound guided vascular access.

When I started as a paediatric registrar, I’d just finished an adult ICU term where I’d become spent a majority of time supporting provision of a vascular access service, and as part of this had become a PICC line insertion instructor. Eventually, I got to the point where I dreamt of abstract grey shapes. But then I started a paediatric job in a regional hospital where it seemed that ultrasound was used for vascular access rarely if at all. Initially, I thought there must have been something different about paediatric vascular access that I was unaware of. One day, when looking after a young lady with Rett’s who was known to be difficult to cannulate, I reached for the ultrasound. In the five years since, ultrasound has been a standard part of my practice in achieving vascular access in children, with technique adapted to fit the age of the patient.

Ultrasound-guided vascular access and paediatrics seem like such a natural partnership. The concept of a DIVA (“difficult IV access”) patient is receiving increasing interest and research. Criteria for a DIVA can include prematurity, inability to see or feel a vessel, or an episode of multiple prior attempts. These criteria would be met by a huge number of the kids we care for, in particular toddlers or the previously premature infant. 

Chonky baby arm
Spot the veins

Why is ultrasound not the first-line adjunct in these tricky kids? It’s probably multifactorial, but certainly, ultrasound is more difficult in children than adults. Its utility is varied in the NICU context and for infants under 2.5kg, although can still have a role with a modification to technique. It’s also harder to learn ultrasound in a population who are scared, angry, impatient and poorly tolerant of a prolonged period of needle-through-skin. For these reasons, I think that there is less appeal to replace the familiar (cannulating without an ultrasound), with the unfamiliar (cannulating with an ultrasound). As I’d experienced, this also leads to a culture where ultrasound is infrequently utilized, decreasing the likelihood of implementation by new or more junior staff.

Once the learning investment is made to reach a proficient level of ultrasound competency (about 20 cannulas in adults) the potential benefits are significant. Decreased time spent performing a procedure, decreased number of attempts and subsequent patient trauma, and increased cannula longevity are all achievable.

I’ve spent a lot of time thinking success optimisation in paediatric ultrasound guided cannulation, both during my own development of proficiency and then in an effort to verbalize this skill when educating others. Below are my 5 top tips to enhance your ultrasound-guided cannulation skills:

I’m hoping that some of these words may help avoid some bits of the inevitable trial and error process that comes with learning a new skill.

There is sometimes a general impression of both practical and personal inconvenience in using ultrasound for vascular access. An ultrasound may not be nearby. There is the fear of “looking silly” in front of other people, as turning on, adjusting, and then physically coordinating the use of the ultrasound may be unfamiliar. During the period of establishing proficiency, an approach to decreasing this sense of unfamiliarity is to get in the habit of bringing the ultrasound with you do a cannula. Turn on and optimize the ultrasound to view vessels, and spend a period mapping out candidates for cannulation using your non-cannulating hand. Draw on the patient with a skin pen if you want to keep track of the best sites. Then, discard the ultrasound and cannulate using whatever technique is most familiar to you, but with the added knowledge of vessel location, depth, size, and direction. If this becomes a routine and almost ritualistic process, the mental barrier created by a lack of familiarity with ultrasound settings and holding the transducer should decrease over time. It is a relatively small step from performing vascular mapping to placing a cannula under real-time ultrasound guidance.

The preparation otherwise is quite straightforward. In addition to the set up that you use for all other cannulas, you need the following four things:

  • An ultrasound with a linear array probe (the smaller the footprint and the higher the frequency, the better)
  • Sterile lubricating gel and some form of sterile barrier to cover your probe (this varies institutionally)
  • Cavilon wipe or skin prep (securement devices / dressings / tape doesn’t like to stick to ultrasound gel so will need some encouragement)
  • An extra person (one of your hands is out of action, so you need an additional person to perform the task that your non-dominant hand would normally do; this is typically stabilization of the distal limb)

The ultrasound sits on the opposite side of the bed to the operator, so as to minimize truncal movement in looking from the puncture site to screen. Aside from making sure the correct probe is selected, the only 3 settings you need to know how to adjust are depth (typically as shallow as possible), gain (similar to a ‘brightness’ setting to highlight blood-filled vessels), and a midline marker (for physical-digital landmark referencing).

As alluded to above, pre-scanning is a useful skill even in the absence of cannulating under real-time ultrasound guidance. It’s a good idea to scope out the most appropriate vessels and puncture sites prior to picking up your cannula. Essentially the objective is to place a cannula within a vessel with as few attempts as possible, as quickly as possible, with as little pain as possible, and in a site that will provide the greatest longevity. Characteristics of vessels that tend to correlate with these outcomes are:

  • long and straight stretches
  • vessel 6mm or less below the surface
  • vessels greater than 2mm in diameter
  • vessels that don’t cross a joint (provides freedom of movement and less extravasation)
  • vessels without upstream thrombosis or obstruction

Mid-forearm vessels often meet the above criteria.

The greater length of cannula able to be placed within the vessel can correlate with longevity, however larger cannula diameter may increase the phlebitis and decrease longevity. This requires consideration of the balance between length and diameter of device. Of the commonly available devices, a good balance is a blue cannula (22G). There are several specialised less widely available devices that are longer versions of small diameter cannulae (24G and 22G).

In practical terms, to find these vessels you can start in the antecubital fossa (more familiar area for most of us) and track them down, or plonk down on the forearm and pan circumferentially. Scanning in the short axis / transverse axis / cross-sectional view tends to work best in kids. To assess suitability, translate the probe up and down along a vessel to get an idea of the direction. If it’s running diagonally, rotate your probe until it’s running along the same plane as the vessel to act as a mental reminder of the angle/direction that you need to insert your cannula. Pick the specific spot on the vessel that you’d like to puncture, bearing in mind that you will be puncturing the skin millimetres back from that point. Pick the patch of the vein that is the longest, straightest, shallowest, and biggest. Have a second fallback site planned out elsewhere for if required. Lastly, make sure to track the vein proximally as far as you can to ensure that it doesn’t run into a large thrombosed/occluded/recannalizing patch of vessel.

Obscure angles make things more challenging, in my experience. Right angles and parallel lines are your friends because they assist in mental unburdening and allow you to devote energy to troubleshooting issues. As mentioned above, map the vessel prior to puncture. Part or all of a vein will often wander diagonally along its journey, so approaching from the wrong direction increases the likelihood of punching through the side of the vessel. The centre of the image corresponds to the arrow/marker along the long edge of the probe, so you have a reference point between digital (screen) and physical (skin). Use the ultrasound as a mental reminder of your plane of approach; rotate the probe until the vessel is consistently sitting in the very centre of your image as you plane up and down. In other words, the ultrasound image is perfectly perpendicular to the plane of the vessel.

Speaking of right angles, I prefer to keep the ultrasound at right angles to the surface that you’re scanning. Angling back and forth creates a loss of contact and a distorted image as the ultrasound bounces of structures and does not return to the transducer. This creates a less clear image where vessels artificially look larger. If you need to change your view, translate/glide the probe along the skin, rather than introducing angle. It can be useful to temporarily angle the transducer perpendicular to the shaft of the cannula if you lose sight of it as this will light it up more clearly.

This is a big one. Thinking of your cannulation as a two-phase puncture process is something that I find extremely helpful. Your objective is not to puncture the skin and end up inside the vessel in a single action, and in fact, attempting to do this seems decrease the likelihood of success. 


Puncture Phase 1

Puncture 1 is the process from skin puncture to positioning the tip of your cannula on the superficial wall of the vessel. To achieve this, align your probe to achieve a view with the vessel in the centre of the image. Puncture the skin with the cannula a few millimetres distal to the probe. This bit is painful, so do this with a decisive action so that 2-3 mm of the cannula is within the soft tissue. Increase your angle of insertion to 30-45°. Your next objective is to find the tip of the cannula. Moving your non-dominant (ultrasound) hand, translate/slide the probe towards the puncture site until a glimmering white dot becomes apparent in your image. Once you are convinced that you are viewing your cannula, you need to ensure that you are viewing the tip at all times.

The most important thing to remember is the only way to be certain that you are viewing the tip of your cannula is when the glimmering dot disappears when you move the probe 1mm proximally (away). It is frustratingly easy to think that you are viewing your cannula tip when instead you are halfway along the shaft, with the tip out the deep wall of the vessel. Maintain this view via a “walking” approach. For each 1-2mm advancement (step) of the cannula, make an equivalent proximal movement with your ultrasound probe (step). Move the ultrasound away so that you cannot see cannula tip anymore, and then advance the cannula into view. If needed, intermittently stop advancing your cannula and check your tip position as described above. I find advancing at 30-45° until you reach the vessel works well as minimal cannula is wasted on the journey there.

If you find yourself wandering off track, keep the ultrasound focused around the vessel as the centre of your image (as this is your target). Correcting if off centre is slightly counterintuitive. Move your cannulating hand away from the direction that you want to move your cannula tip (ie- moving right will move the tip left). Continue inserting until your cannula tip is sitting at 12 o’clock on top of your vessel. As you reach this point, the tip of the cannula may gently tent the roof of the vessel, turning an “O” shape into a “❤️” shape. This is a good test of correct positioning. Once you’ve reached this point, you’re ready for puncture phase 2!!

 Puncture Phase 2

Puncture 2 is the process of entering the vessel to feeding your cannula fully in. With the tip of your cannula in view and the roof of the vessel tented (❤️), continue incrementally advancing your cannula with tiny movement, walking the ultrasound forward to ensure the tip remains in view (as above). Gently decrease your angle of insertion so that the superficial wall is not tenting towards the deep wall but rather into the potential space of the proximal vessel. Eventually, your tented vessel (❤️) will suddenly encompass the cannula and return to a circular shape (O). This may be associated with a tactile pop. You can check for flashback for additional confirmation of vessel puncture, but I prefer to not take my eyes off the ultrasound screen at this point.

Continue decreasing your angle of insertion to maintain the tip of the cannula in the top 50% of the vessel (keep the sharp bevel away from the deep wall). This may eventually require you be pushing the cannula into the skin, which really requires your assistant to get out of the way. Don’t lose site of your tip! Continue to step forward; cannula then ultrasound. To check whether you are in the vessel and not in soft tissue or dragging on the vessel wall, waggle the tip of the cannula around gently (left, right, up, down). There should be absolutely no distortion of the soft tissue surrounding the vessel; completely free cannula tip movement. I tend to leave the metal stylet in until the plastic catheter is fully inserted to the hub because of greater visibility and added rigidity. This does, however, carry the risk of puncturing the back or sidewall of the vessel if you don’t keep a close eye on your cannula tip. At the very least, ensure 3-4mm of the cannula is inside the vessel lumen prior to gliding the plastic catheter off (to avoid tissuing / tearing the vessel roof). Once this is done, you’ve just successfully place a real-time ultrasound-guided cannula! Well done!

I think it’s reasonable with each healthcare interaction to measure success both in the resolution of issue (beneficence) and in minimization of harm / traumatic experience (non-maleficence). Vascular access is our commonest painful procedure, hence representing a significant potential burden of pain, anxiety, and trauma. Undertaking steps to minimize vascular access attempts, maximize speed/efficiency, and maximize cannula longevity are important considerations in the healthcare interaction. Even if we manage to achieve the elusive goal of a single puncture hospital admission, this still requires a single puncture. 

This discussion is not really directed towards addressing the specifics of analgesia and sedation but suffice to say that time permitting these should be used and optimized readily. A topical anaesthetic is valuable, although in the case of an ultrasound-guided cannula application by the operator is useful in ensuring good placement. Evidence is increasingly suggesting that topical anaesthetic is appropriate in all ages including neonates.

The power of social stories, rehearsal, music therapy, and just general distraction cannot be undervalued. There is a multitude of approaches to this. 

Unfortunately, it is not an uncommon experience to be in a situation where vascular access is required with a degree of clinical urgency. In this circumstance, oral/intranasal/topical medication may have not had time to work, and a specialist in distraction may not be readily available.

In this circumstance, I have found that playing calm and quiet music more useful than positioning a video in front of a child. Maintaining a minimum of people speaking, and using quiet calm voices is valuable. I have had some success using the ultrasound itself as a distraction modality while telling the child a story of the “doughnut that has lost its hole” (vein and cannula tip respectively) as the tip tracks toward the vessel. A variant is the “star that fell from the sky into the lake” (cannula tip and vein respectively). There are many approaches to pain reduction through distraction.

It is my sincere hope that these tips are of some practical and clinical value in your cannulating endeavours. If it makes a difference for a single child, then surely it’s worth it. Good luck!

To CT or not to CT?

Cite this article as:
Dani Hall. To CT or not to CT?, Don't Forget the Bubbles, 2020. Available at:

Does introduction of a national guideline improve c-spine injury detection?

A wise paediatrician once told me that practicing medicine is part art, part science. Pathology and decision making are not always black and white. Sometimes we have to interpret the grey areas, balancing risk.

Cervical spine injuries in children are rare but missing a c-spine injury has devastating consequences. On the flip side, we are taught to apply the ALARA principle whenever deciding whether a child needs a CT.

ALARA stands for As Low As Reasonably Achievable and is a constant consideration for children whose tissues are very radiosensitive to minimize the lifetime risk of cancer. Obtaining good c-spine x-rays can be tricky and interpreting them requires skill. When managing children with potential for cervical spine injury we ask ourselves does this child need imaging of their c-spine and should it be a CT? In 2014 the National Institute of Health and Care Excellence, NICE, introduced a decision rule to help us select which children need c-spine imaging, and whether it should be by x-ray or CT. This was replicated in the Royal College of Radiology Paediatric Trauma Protocols, published that same year. The guidance describes seven indications for CT, six for CT without an x-ray and the seventh for when there is uncertainty following x-ray:

  1. Children with a GCS <13 on initial assessment
  2. Intubation
  3. A definitive diagnosis of c-spine injury is required
  4. Other body areas are being scanned for head injury or multi-region trauma
  5. Focal peripheral neurology
  6. Paraesthesia in the upper or lower limbs
  7. 3-view c-spine x-ray demonstrates a significant bony injury, was technically difficult to perform or inadequate, or was normal but with a strong clinical suspicion of injury

NICE describe a caveat to this list: don’t automatically CT a stable child’s c-spine if you’re organising a CT head. NICE recommends the decision for CT versus x-ray should be made on a case-by-case basis after a discussion between a senior ED clinician and senior radiologist. We’ll come back to this later.

Six years on, Catherine Nunn and colleagues have published a paper assessing the impact of the introduction of the NICE c-spine guideline on both the number of c-spine CT scans requested and the number of c-spine injuries diagnosed.

Nunn et al. Have changes in computerised tomography guidance positively impacted detection of cervical spine injury in children? A review of the Trauma Audit and Research Network data. Trauma. 2020 DOI: 10.1177/1460408620939381

What question did the study team ask?

Nunn and her team looked back at data of children under the age of 16 in the Trauma Audit and Research Network (TARN) in two time periods, 2012 – 2013 and 2015 – 2016, to capture a before and after assessment of the NICE guideline. They gathered the following information from the TARN database:

  • How many children young people under the age of 16 years had c-spine CT imaging?
  • How many had a c-spine injury (CSI)?
  • What was the mechanism of injury?
  • Was there a different between major trauma centres and trauma units?

A bit about TARN

TARN is a national organisation in the UK, and the biggest trauma registry in Europe, collecting data on moderately and severely injured patients from both major trauma centres (MTCs) and trauma units (TUs). Since its introduction in the 1990s, its data has been integral to quality and research initiatives in trauma care. Patients are included in the registry if they require critical care, are transferred between hospitals for ongoing acute critical care, have a hospital length of stay of more than 3 days or if they die as a result of their traumatic injury. Patients who don’t meet these criteria are not included in the database.

What did the study team find?

Did the NICE guideline increase the specificity of detecting a c-spine injury?

Following the introduction of the NICE guideline, there was a decrease in the proportion of children who had a cervical spine CT, from 13.7% to 12.1%, but this wasn’t a statistically significant drop.

What the team did find was an increase in the rate of injury in the children who were initially imaged with CT, from 10% to 16.4%, meaning the specificity of the selection of children for CT c-spin improved after the introduction of the guideline.

Over 80% of children received high risk radiation to the neck and had no injury. Balancing the risk of radiation against missing an injury continues to be a challenge.

Unsurprisingly, road traffic accident was the most common cause of c-spine injury, followed falls.

What about major trauma centres versus trauma units?

Trauma networks were introduced in the UK a decade ago, dividing regions up into a hub major trauma centre (MTC) with spoke trauma units (TUs). Although MTCs are designated to deliver high-quality specialist trauma care, with efficient pathways getting children to scan as part of more specialized care, severely injured children often present to a TU. Nunn’s team found that the introduction of the NICE guideline was associated with a reduction in the percentage of c-spine scans in both MTCs and TUs: both MTCs and TUs were more selective about which children had a c-spine CT.

Trauma Units were more selective in their choice of children undergoing cervical spine CT with a lower proportion having a CT, but a higher proportion of those scanned having a c-spine injury, meaning there was a higher sensitivity of scan in TUs.

This might reflect the caveat suggested by NICE that we shouldn’t automatically CT a stable child’s c-spine when organising a CT head and the decision in these circumstances should be made on a case-by-case basis. Nunn’s team suggest that the efficiency of MTCs getting patients to scan means that more children are being scanned rapidly (as the pathways intend), but more are scanned who are less likely to be injured (meaning more children are exposed to radiation who don’t have an injury).

Is CT the best imaging modality?

Nunn’s team found that 20% of the CT scans in both time groups were falsely negative. Put another way CT only detected 80% of the c-spine injuries, with the other 20% being picked up on subsequent MRI. SCIWORA, or Spinal Cord Injury Without Radiological Abnormality, is a phenomenon particular to children, who may have spinal cord or ligamentous injury that cannot be seen on x-ray or CT.

Is there a role for MRI instead of CT? MRI is much more sensitive in detecting cord and ligamentous injuries but is logistically challenging because these scans aren’t quick – younger children need sedation or general anaesthetic – and putting severely injured children in an MRI for up to 40 minutes is risky. Nunn’s team suggested there will be times skipping CT altogether and performing a delayed MRI, maintaining c-spine precuations until a child is more stable, might be more practical.

The bottom line

Introduction of a paediatric c-spine CT decision tool had a positive impact. The sensitivity of detecting a c-spine injury increased, and fewer children proportionately had CT scans without injury. Twenty percent of children with c-spine injury had negative CT scans so the question remains, should early MRI be advocated instead of CT in a group of children with suspected injury?

Infographic by Emma Hudson

Imaging in COVID

Cite this article as:
Nuala Quinn, Cian McDermott and Gabrielle Colleran. Imaging in COVID, Don't Forget the Bubbles, 2020. Available at:

The current pandemic is providing a challenge in healthcare settings whose resources are rapidly becoming strained. From the early experiences in China, it appears that children who are infected with COVID-19 have a milder course typically than that seen in adults. The radiological findings in adults include multifocal bilateral ground-glass opacities and consolidation. This is often peripheral or basal in distribution. They tend to evolve from either these bilateral ground-glass opacities on the periphery to consolidation then crazy paving. The limited initial data in children suggest that multi-lobar involvement is much less common. This is consistent with the hypothesis that children appear to have milder disease. Findings peak at 7 to 14 days and then gradually resolve. We do not yet know the radiologic sequelae.  Experience taken from the adult population in Ireland has also noted air leak complications including pneumomediastinum and pneumothorax. Pleural effusions, lymphadenopathy, and tiny lung nodules seem to be less common manifestations.



The chest x-ray is, in general, the first-line imaging in children with respiratory pathology. And it is being used in COVID-19. This (pre-publication) CXR is from a case in a tertiary paediatric hospital. It shows bilateral mid-zone and left lower zone patchy consolidation and pneumomediastinum.

Ming-Yen et al describe five patients who had both chest x-rays and a CT of the thorax. Two patients showed normal CXR findings, despite having a CT examination on the same day showing ground-glass opacities. The positive CXR findings seem to appear later in the disease progression. Within the Guangdong province of the authors, a CT of the thorax is now being requested on every patient suspected of having COVID-19 regardless of risk. However, the radiation associated with CT in children does not, and cannot, support this in the paediatric setting. In sticking to the ALARA (As Low As Reasonably Achieivable) we should consider the use of another evidence-based resource – point-of-care ultrasound (POCUS).

Point of care ultrasound (POCUS) is fast becoming an established part of paediatric emergency medicine. Lung ultrasound is a mainstay of POCUS for a variety of diagnoses including pneumonia and pleural effusion. Now, there is rapidly evolving evidence on COVID-19 and POCUS lung findings.

So, how do we use ultrasound to look for ground-glass opacification and consolidation in children with suspected viral respiratory tract infection?


Sonographic characteristics


Lung US is more sensitive than CXR for interstitial patterns, small effusions, and subpleural thickening. The POCUS characteristics are similar to other causes of viral pneumonia, but in COVID-19, two studies (Huang et al and Peng et al) also described localized pleural effusions. They are more often seen with bacterial pneumonia in children, rather than viral. Large volume pleural effusions are uncommon – if you are seeing this then you need to consider other pathology.

B-lines are short-path reverberation artefacts that are found in many pathological and nonpathological states. *ISP is interstitial syndrome pattern, i.e. extensive B lines which may coalesce. This pattern is not unique to COVID-19. It is also commonly seen in pulmonary oedema. In COVID-19 these may appear in characteristic focal, multifocal and confluent patterns.

Small subpleural consolidations may be also seen. These are small hypoechoic areas inferior to the pleural line. If there is bibasal consolidation on the ultrasound, there may also be dynamic bright air bronchograms present. In COVID-19, a pleuropathy develops. This results in a thickened, irregular appearance of the pleura. There may also be skip lesions – normal pleura alongside thickened pleura with associated B-lines.

It is important to note that children may be clinically well with any of the positive lung POCUS findings.

Technique tips

The technique for POCUS lung is well described. However, for children and COVID, the following may be helpful:

  • Use the linear probe to assess pleura and look for pleural line thickening, small superficial effusions, skip lesions and B-lines.
  • Use the curvilinear or phased for lung windows. It may also be better for posterior pathology such as consolidation and air bronchograms.
  • Turn off the harmonics and spatial functioning.

And if you don’t know what any of that means then head over to Practical Pocus for a free online course and follow @Zedunow for their daily updates.


Decontamination and machine preparation

Infection control measures are key – the machine should go in clean and come out clean! ACEP have published an excellent COVID US cleaning protocol which is really worth a look at.

Remember to strip the machine of all non-essential items such as trays, holders and inserts and where possible avoid keyboards and use the touchscreen. Rather than multi-use bottles of gel, you should be using single-use sachets.

Handheld devices provide an alternative, with less cleaning required.


Photo courtesy of Cian McDermott

A word on CT

The CT findings associated with COVID-19 have been widely described: ground-glass opacities and consolidation with or without vascular enlargement, interlobular septal thickening ,and air bronchograms. Most of the studies are in affected adults and the high reported sensitivity will be affected by patient selection bias. Like the chest x-ray, it may be falsely negative in the first few days of illness. A normal CT early in disease could be falsely reassuring. Indeed, the general guidance from numerous faculties of radiology does not currently recommend CXR or CT to diagnosed COVID-19. Viral testing remains the gold standard.


Finally, a word on ALARA

ALARA, or making every effort to limit exposure to radiation As Low As Reasonably Achievable, is particularly relevent in COVID-19. Imaging should only be conducted for those patients where imaging will impact management of the condition. These recommendations may change as our knowledge of COVID evolves. CXR, CT and POCUS each have their own limitations, but there is emerging evidence that POCUS, in the hands of a competent practitioner, is superior in ease of access, diagnostic ability and ease of decontamination, particularly at a time when infection control is so crucial.


Selected references

Kanne JP, Little BP, Chung JH, Elicker BM, Ketai LH. Essentials for Radiologists on COVID-19: An Update-Radiology Scientific Expert Panel. Radiology. 2020 Feb 27:200527. https://pubs.rsna.org/doi/pdf/10.1148/radiol.2020200527.

Liu M, Song Z, Xiao K.High-Resolution Computed Tomography Manifestations of 5 Pediatric Patients With 2019 Novel Coronavirus.J Comput Assist Tomogr. 2020 Mar 25.

Ming-Yen N et al. Imaging Profile of the COVID-19 Infection: Radiologic Findings and Literature Review. Radiology 2020 Feb 13 https://doi.org/10.1148/ryct.2020200034

Huang Y et al. A Preliminary Study on the Ultrasonic Manifestations of Peripulmonary Lesions of Non-Critical Novel Coronavirus Pneumonia (COVID-19) SSRN 2020 Feb 28 https://dx.doi.org/10.2139/ssrn.3544750

Peng, Q., Wang, X. & Zhang, L. Findings of lung ultrasonography of novel corona virus pneumonia during the 2019–2020 epidemic. Intensive Care Med (2020). https://doi.org/10.1007/s00134-020-05996-6

Li Y, Xia L. Coronavirus Disease 2019 (COVID-19): Role of Chest CT in Diagnosis and Management. AJR Am J Roentgenol. 2020 Mar 4:1-7. doi:10.2214/AJR.20.22954


International Society Guidelines

Royal Australian and New Zealand College of Radiologists

Canadian Association of Radiologists 

American College of Radiology statement on CXR and CT findings in COVID19

Royal College of Radiology statement on CT in COVID

Pelvic avulsion injuries

Cite this article as:
Owen Keane. Pelvic avulsion injuries, Don't Forget the Bubbles, 2019. Available at:

Ben, a 14-year-old competitive sprinter, limps into your emergency department complaining of sudden onset severe pain and a “pop” felt in his left hip shortly after the start of his National Athletics 100m Final. He points to a specific area on his pelvis and walks with an antalgic gait. Further examination reveals pain on left hip flexion and an appreciable weakness on active flexion compared to his right side. Mum tells you that Ben has complained of pain during and after heavy training for the last few weeks, but this seems to settle with rest and icing after each session.


Case courtesy of Dr Mark Holland , Radiopaedia.org. From the case rID: 16820


Ben and Mum are keen to know what you think of his x-ray.
What is his diagnosis, how are you going to manage it and what are his chances of making the International Schools Team trials in 3 weeks’ time?



Injuries to the apophysis range from recurring painful episodes of apophysitis to avulsion fractures of these secondary ossification centres. Avulsions often present with reports of a “pop” followed by severe pain and weight-bearing difficulties. There is a reported injury predominance in adolescent males of over 70%, with sports involving kicking or sprinting most likely to be involved.

As the participation of adolescents in competitive sport increases so too are reports of apophyseal avulsion injuries. The young athlete is becoming more powerful with stronger muscle groups enhancing physical abilities. Coupled with weaker apophyses, these factors lead to a higher incidence of avulsion fractures in this group.

Early diagnosis and appropriate management is necessary to reduce the risk of chronic pain, disability and reduced participation in physical activity. Apophyseal injuries can be misdiagnosed as “muscle strains” due to a failure to appreciate the anatomical uniqueness of this population making their injury pattern distinct from that of adults. The impact of a delay to diagnosis on long-term health, sports participation and development could be profound.


Anatomy and Mechanics

The apophysis (also known as a traction epiphysis) is a secondary ossification centre that serves as a site for musculotendinous attachment. It arises as a separate bony outgrowth and fuses with the main bone over time. These helpful table illustrations from a publication by Moeller in 2003 highlight the various expected ages of opening and closing of the various pelvic apophyses:


Tensile forces from strong muscular contractions are experienced at the pre-pubescent and adolescent apophysis during sporting activities. We know of several factors which make these structures more susceptible to avulsion injury:

  • Ligaments, tendons and muscles are stronger than their bony apophyseal outgrowths.
  • Pubescent bone is subject to transient deficiencies in minerals during periods of rapid growth. The resulting porous bone is weaker and more susceptible to injury.
  • Chronic repetitive physical loading and tensile stresses across the musculotendinous attachment to an apophysis can predispose to acute avulsion type injuries.

The mechanism of injury in avulsion fractures is based on sudden ballistic movements that are experienced during “explosive” type activities like sprinting, kicking, twisting or jumping. Sudden forceful muscular contractions lead to eccentric loading of the tendon insertion at the apophysis. This then results in the separation and retraction of the apophysis away from its origin at the pelvis or femur.

Ischial tuberosity (54%) and anterior inferior iliac spine (22%) avulsions are the most common types of fractures reported in the adolescent population. Although rare, 5 patients from a study by Rossi and Dragoni in 2001  were reported as having two fractures so be sure to review all apophyseal sites before committing to a final diagnosis.

The various muscles and their corresponding apophyses are shown in the image below:

Radiographic Examples

Left AIIS avulsion. Results from strong eccentric contraction of long head of rec femoris while hip is extending, and knee flexed. Classically associated with kicking a ball.


Left ASIS avulsion – “Hip pointer”. Caused by sudden and forceful contraction of sartorius and tensor fascia lata. Occurs during hip extension (sprinting, swinging a bat). Image from Orthobullets.


Left ischial tuberosity avulsion. Caused by sudden forceful contraction of the hamstrings. Case courtesy of Dr Andrew Dixon, Radiopaedia.org. From the case rID: 30012


Left lesser trochanter avulsion. Caused by sudden forceful contraction of iliopsoas during sprinting.


Management, Prognosis and Recovery

Most injuries are managed conservatively with initial rest and symptomatic support in the form of ice, protected weightbearing and analgesia. Gradual reintroduction to weightbearing with early range of motion (ROM) and strengthening should be progressed under the guidance of a physiotherapist.

While specifics may vary, a good conservative approach to managing these injuries could be:

  • Protected weightbearing with crutches for 2-4 weeks until painless normal gait is achieved.
  • Gentle ROM and strengthening exercises from weeks 4-8 with physiotherapy.
  • Consider return to sport at 8-10 weeks if pain is minimal with squatting and jumping.
  • Return to full sporting activity should only be considered once the patient is pain free doing sports-specific movements.

Open reduction and internal fixation is considered for fractures with displacement of >2cm or those with chronic pain secondary to painful non-unions. The goal of surgery is to reduce the time to return to pre-injury level of physical activity. Fracture displacement of >2cm has been reported to increase the risk of non-union by up to 26 times, with AIIS and ischial tuberosity fractures also being an increased risk of developing nonunion complications. Sundar and Carty reported significant difficulty in returning to sport in 75% of ischial tuberosity avulsion cases with 25% of these athletes dropping out of sport altogether. A large case series by Schuett et al highlighted that 14% of all patients reported pain more than 3 months post injury, with patients with AIIS avulsions much more likely to report chronic pain.

It is important to counsel patients and parents about the small risk of chronic pain or non-union before disposition from ED and the potential need for delayed surgical intervention in the future.


Thanks to your keen eye for x-rays and knowledge of adolescent sports hip pathology, you diagnose Ben with a left sided ASIS avulsion (“Hip pointer”). You reassure Ben and Mum that this injury is unlikely to require surgery but explain that it will need rehabilitation with his local physiotherapist over the next few weeks. Ben’s devastation is clear for all to see after you express worry that he may not make his important International Schools Trial in three weeks’ time…but thankfully he quickly reassures himself as he has two more years at this age group and fancies his chances next year!



Moeller JL. Pelvic and Hip Apophyseal Avulsion Injuries in Young Athletes. Current Sports Medicine Reports. 2003; 2:110–115

Rossi F and Dragoni S. Acute avulsion fractures of the pelvis in adolescent competitive athletes: prevalence, location and sports distribution of 203 cases collected. Skeletal Radiol. 2001; 30:127–131.

Schuett DJ, Bomar JD, Pennock AT. Pelvic Apophyseal Avulsion Fractures: A Retrospective Review of 228 Cases. Journal of Pediatric Orthopaedics. 2015; 35(6): 617–623

Sundar M and Carty H. Avulsion fractures of the pelvis in children: a report of 32 fractures and their outcome. Skeletal Radiol. 1994; 23:85–90.


Seat Belt Injuries

Cite this article as:
Keith Amarakone. Seat Belt Injuries, Don't Forget the Bubbles, 2019. Available at:

A 10 year old boy presents to your emergency department following a high speed MVA – car vs tree. He was seated in the rear middle seat.  On arrival he is noted to have significant bruising across his lower abdomen from the seat belt but otherwise appears well.

Skeletal survey for NAI

Cite this article as:
Katie Mckinnon. Skeletal survey for NAI, Don't Forget the Bubbles, 2019. Available at:

In November 2018 the revised edition of “The radiological investigation of suspected physical abuse in children” was released in the UK. This was written by the Royal College of Radiologists and the Society and College of Radiographers, and endorsed by the Royal College of Paediatrics and Child Health. It produced guidance on the process of skeletal surveys and how and when to perform them.

The management of non-accidental injury is an area of fear for many paediatricians. The increasing guidance in this area helps to take some of the variation in practice out of the process.

Thoracolumbar spine x-rays

Cite this article as:
Tessa Davis. Thoracolumbar spine x-rays, Don't Forget the Bubbles, 2019. Available at:

Read our step-by-step guide to interpreting thoracic and lumbar spine x-rays.

Thoracolumbar spine x-ray involves two views – AP and lateral.


  1. Check it’s an adequate view

For a lumbar spine view

  • you should be able to see L1-L5 but also the full T12 vertebral body, T11/12, and the sacrum on the AP view
  • the vertebral bodies, facet joints, and pedicles should be clearly visible on the lateral view
  • the transverse processes should also be visible (and are often obscured by gas)

For the thoracic spine view

  • make sure the whole thoracic spine is visible
  • you should be able to see the pedicles, spinous processes, and vertebral bodies
  • the ribs can cause difficulty seeing the thoracic spine on a lateral view


2. Know your anatomy

  • Clavicle is at T3
  • Tracheal bifurcation is T4/5
  • 12th rib is at T12
  • In the lumbar spine, the disc spaces also increase in size, although note that the L5/sacral space is narrower than the L4/L5 space

From https://www.wikiradiography.net/

3. Check the alignment

On the AP check that the vertebral bodies and spinous processes are aligned. On the lateral, check the alignment of the vertebral bodies.



4. Look for loss of vertebral height

In the thoracic spine, the vertebral bodies (and the disc spaces) should gradually increase in size as you get further down the spine.

Check all the vertebral bodies looking specifically for loss of height. This indicates a compression fracture.




5. Look for widened inter-spinous or inter-pedicle distance and check the processes

In the lumbar spine check that all the pedicles, spinal, and transverse processes are intact.

See below (under burst fracture) for an example of widened inter-pedicle distance and (under Chance fracture) widened spinous process process distance.

Transverse process fracture From https://www.imageinterpretation.co.uk/thoracolumbar.php


6. Check for translation/rotation or distraction

Translation or rotation is displacement in horizontal plane; and distraction is displacement in the vertical plane.

Translation/rotation is due to a side-to-side motion (can be left-to-right or front-to-back). It is a serious injury and always involves the posterior ligamentous complex.

Distraction is where the vertebrae are pulled apart and carries a high risk of cord injury. Often there is compression at the other side (see Chance fracture below).


7. Know the common types of fractures

Compression fracture

This is the most common type of fracture and is identified through loss of vertebral height (see number 4 above). It involves one column only and is a stable fracture.


Burst fracture

On x-ray alone 25% of burst fractures are misdiagnosed as vertebral compression fractures. A burst fracture is where there is a compression, but part of the vertebral body has been projected out anteriorly.

On AP view there will be an increased interpedicular distance in 80% of burst fractures.

On lateral view there will be reduced vertebral height and disrupted anterior alignment.

A burst fracture involves two columns and is usually considered to be unstable.


Chance fracture

Usually from a seatbelts injury and is commonly at L2/L3

This is a flexion-distraction injury where there is horizontal splitting of the vertebral body with ligament rupture. This is an unstable fracture and involves all three columns

Sometimes there is increased distance between the spinous processed on the lateral view (but not always).

On the AP view there can be increased distance between the spinous processes at the level of the Chance fracture.


Jumper’s/lover’s fracture

So-called because it’s usually from people jumping out of windows to escape the police or angry partners. This is severe axial loading leading to compression/burst fractures alongside a calcaneus fracture.




Radiology Assistant

Norwich Image Interpretation Course

Radiology Masterclass

Diagnosing DDH

Cite this article as:
Andrew Tagg. Diagnosing DDH, Don't Forget the Bubbles, 2018. Available at:

When people approach me to ask about writing for DFTB I usually suggest that they write about what they know.  That is certainly my approach and why I started to write the Normal Neonate series a year ago. The littlest Tagg has just had her year’s check up with the maternal and child health nurse. She thought that tiny Tagg had uneven buttock creases and wanted her assessed for DDH. But how sensitive is this sign?

Focus on PEM POCUS

Cite this article as:
Cian McDermott and Pete Snelling. Focus on PEM POCUS, Don't Forget the Bubbles, 2018. Available at:

Point-of-care ultrasound (POCUS) is a disruptive technology that has the potential to change the standard way children are evaluated and managed, particularly in the paediatric emergency medicine (PEM) department.  POCUS is a complex skill that needs to be broken down into bite sized components and the aim of this new DFTB series will give you the framework to get started and then go through specific applications as well as the evidence. This introductory post sets the scene.

C-spine x-ray interpretation

Cite this article as:
Chris Partyka. C-spine x-ray interpretation, Don't Forget the Bubbles, 2017. Available at:

The ABC’s of the cervical spine provide a helpful mnemonic to guide the systematic assessment of these x-rays. Remember; you require all three views (lateral, AP and odontoid/open mouth view) for an adequate study.