SonoTips&Tricks: The FAST scan: Suprapubic View #FOAMus #FOAMed

By Viveta Lobo, MD and Laleh Gharahbaghian, MD, FACEP

Our latest insert in the ACEP Ultrasound Section newsletter is below – on the FAST scan – the Suprapubic sections. The prior entries was on the FAST scan: The Cardiac views ( go here) and The Upper Quadrants ( go here. ). The ACEP US Section is the go-to site for everything you want to know about starting an US program, credentialing in ultrasound, the policies and politics, and is the home of SonoGuide – an amazing educational resource for bedside ultrasound, and the EMSONO: Ultrasound Test. It is also where we add our entries for their newsletter that goes over tips and tricks, cases, and all things ultrasound in the news. We recently wrote an article for the ACEP Ultrasound Section Newsletter – which is available for all members of the ACEP US Section – and I highly recommend becoming a member – it’s totally worth it.”

It was a TRUE pleasure to record a podcast recently with Dr. Scott Weingart (aka, my hero) on EMCrit (twitter: EMCrit), and writing this article with our newest ultrasound faculty member, Dr. Viveta Lobo, describes some of what was spoken about.

As discussed in our last entry, the FAST exam is undoubtedly the most widely used bedside ultrasound application used in emergency medicine. Its incorporation in the ATLS revised protocol, the RUSH exam, and several other published protocols, makes it an invaluable screening tool for intra abdominal injury causing hemoperitoneum, cardiac injury with pericardial effusion, and unexplained hypotension.(1,2)

We will continue our discussion of the FAST scan by reviewing the pelvis views, and relay some tips and tricks. Refer to the March 2013 Newsletter for our article reviewing tips for scanning the right upper quadrant (RUQ) and left upper quadrants (LUQ), and the June 2013 newsletter for our article reviewing the tips for the cardiac views.

The Suprapubic View
The suprapubic view on the FAST exam is generally the last of the four views performed.

Theoretically, given its dependent anatomical position, one might logically conclude that it should in fact be the most sensitive view to visualize free fluid; unfortunately, the literature has negated this theory – and in fact this can often be the least sensitive view, largely in part of human error, and especially in pelvic fractures.(1,2,4) Anatomically, when we scan the suprapubic area in both transverse and longitudinal planes, there’s a lot that we see –the bladder, bowel, pelvic bones, pelvic organs, and rectum to name a few. This might make it harder for us to visualize free fluid, and separate it out from these other structures. But here’s a few tips to help overcome these limitations. Begin by placing your phased array or curvilinear probe just above the pubic symphysis, aiming inferiorly/caudad into the pelvis.

 

 

 

 

 

 

 

Tips for the Suprapubic View: 

 

 

 

 

 

 

 

1. Look through a full bladder. A full bladder – The suprapubic view is visualized using a filled bladder as the acoustic window. Not all trauma patients come in with a full bladder and we will not likely go back to the days when a foley catheter used to be placed in order to fill the bladder for visualization. While we are sure our patients appreciate us not doing this anymore – its important to note, that if your patient has an empty bladder, it is best to hydrate them up with the fluids, and repeat the scan when the bladder is more full.(5) With an empty bladder your ability to adequately discern free fluid is very limited. Mostly due to gas scatter from bowel, inadequate depth adjustments, and inability to discern bowel fluid from free fluid. Click Here for a Video of A Normal Female.

2. Adjust your depth – More often than not, when it is time to scan the suprapubic area, your depth is set too deep from scanning the upper quadrants or cardiac views. We often find that a depth of about 13cm to 16cm optimizes your view. The goal is to have your bladder centered on the screen, to easily visualize the areas surrounding the bladder

 

 

 

 

 

 

3. Adjust your gain – The bladder is a fluid filled structure, and as mentioned before, fluid is the “lover” of ultrasound, allowing structures deep to it to be well visualized, however this often creates an artifact called “posterior acoustic enhancement” that produces a hyperechoic and bright area deep to the bladder. This makes it hard to visualize anechoic or black free fluid. One of the biggest pitfalls is not decreasing your gain to accommodate for this, and limiting your ability to pick up anechoic free fluid.
A good rule of thumb, is to ensure that you can easily visualize pelvic organs. If you are able to identify a uterus or a prostate easily, that usually means you have adjusted your gain appropriately. Click Here for a Video of Posterior Acoustic Enhancement.

 

 

 

 

 

 

 

 

4. Look everywhere – Unlike in your upper quadrants, free fluid in the pelvic cavity can in fact collect anywhere – anterior, lateral, and posterior to the bladder as well as anterior, lateral, and posterior to the uterus in female patients. This often is dictated by your patient’s position, the lay of the uterus, how full the bladder is, and the size of the prostate to name a few. We suggest looking in four areas –

a. Look anterior and cephalad to the bladder. Click Here for Video of Free Fluid Anterior to the Bladder. This is especially true if the bladder is empty. At times, free fluid will be mistaken for the bladder and thought to be a septated bladder, when in fact it is free fluid cephalad to the bladder. Click Here for Video of Free Fluid Easily Mistaken for Bladder.

b. Look adjacent/lateral to your bladder; free fluid will collect into a “wedge” shape or triangular shape in between bowel folds which will be most evident with appropriate fanning through the region. Click Here for Video of Wedge of Free Fluid.

c. Look deep/posterior to the bladder between it and your pelvic organs. Click Here for Free Fluid Posterior to the Bladder. Especially in females, you can see a collection of free fluid between the bladder and the uterus. This often looks like boxed shaped anechoic structures that as you fan through will appreciate it not being a “contained” structure.

d. Look posterior to your pelvic organs. Free fluid can collect deep to your uterus or prostate. Click Here for Video of Free Fluid Posterior to the Uterus.

 

 

 

 

 

 

 

 

 

5. Seminal vesicles are also anechoic/black – In males, don’t be fooled by the seminal vesicles. These lie immediately posterior to the bladder, and often appear like a anechoic “bow-tie” shape, with contained fluid and equal on each side.
They will always appear in the same location, and you should fan slowly and carefully through the region to ensure that this is a contained structure and not mistake it for free fluid.

 

 

6. Physiological free fluid in females – In menstruating females you can appreciate some physiological free fluid that may be normal. This is hard to differentiate truly from traumatic free fluid, and you will need to consider the clinical picture – Is there any abdominal pain? Is there abdominal or pelvic trauma? Are her vital signs abnormal? Also, the amount and location of free fluid can help – physiological free fluid is found deep to the uterus, and along its border – it should not be greater than 1/3 the length of the border, anything greater than 1/3 should be considered pathological.

 

 

 

 

 

 

 

7. Fan slowly – While fanning is always important in evaluating any region by ultrasound – we cannot stress it enough when evaluating the suprapubic area. It is impressive and often surprising just how much free fluid can “hide” behind and around the many structures present in this region, and not be visualized unless you dedicatedly fan through the area. It is strongly encouraged to view the suprapubic area in 2 planes – horizontally and longitudinally and fan through each section slowly to make sure you don’t miss any free fluid!(3)

8. Quick Pregnancy Test– In female patients of reproductive age, while performing the pelvic view, take a quick look inside the uterus. You just may quickly get your answer to whether she is pregnant or not but visualizing a gestational sac with fetal pole or yolks sac. However, if you only see a gestational sac and you are performing a FAST scan for unexplained hypotension or shock, this could be an identifier for a pseudosac of an ectopic pregnancy.

 

 

 

 

 

 

 

 

Look out for the next and last entry on the FAST scan – the Lung Views in the next newsletter.

References

1. Abrams BJ, Sukumvanich P, Seibel R, et al. Ultrasound for the detection of intraperitoneal fluid: the role of Trendelenburg positioning. Am J Emerg Med. 1999;17(2):117-20.
2. Friese RS, Malekzadeh S, Shafi S, et al. Abdominal ultrasound is an unreliable modality for the detection of hemoperitoneum in patients with pelvic fracture. J Trauma. 2007;63(1):97-102.
3. Ma OJ, Kefer MP, Mateer JR, et al. Evaluation of hemoperitoneum using a single- vs multiple-view ultrasonographic examination. Acad Emerg Med. 1995;2(7):581-6.
4. Von Kuenssberg Jehle D, Stiller G, Wagner D. Sensitivity in detecting free intraperitoneal fluid with the pelvic view of the FAST exam. Am J Emerg Med. 2003;21:476-8.
5. Blackbourne LH, Soffer D, McKenney M, et al. Secondary ultrasound examination increases the sensitivity of the FAST exam in blunt trauma. J Trauma. 2004;57:934-8.

SonoTips & Tricks: The FAST scan: The Cardiac views #FOAMed

Finishing the ultrasound QA sessions that we do every week at Stanford, I was reminded about how bedside ultrasound is a tool that helps when resources were limited. If you hadn’t heard, there was an Asiana Airlines plane crash at San Francisco International Airport with over 180 patients requiring medical care, 55+ of which came to Stanford. Luckily, we just added 4 new SonoSite EDGE ultrasound machines to our 4 MTurbos and 3 GE Vscan systems the week before – and they sure were used well! The FAST scan was used as a screening tool and to help prioritize those who would go to the CT scanner. Once, again, it is important to know how to do it and do it well.  Our latest insert in the ACEP Ultrasound Section newsletter is below – on the FAST scan – the Cardiac sections. The prior entry was on the FAST scan: The Upper Quadrants ( go here. ) – And Ultrasound Podcast recorded with Cliff Reid about it this week too!

I’ll start with what I’ve said before: “2013 is the YEAR OF ULTRASOUND – and for good reason – there are only a few tools that give us such immediate information that can save a life. The ACEP US Section is the go-to site for everything you want to know about starting an US program, credentialing in ultrasound, the policies and politics, and is the home of SonoGuide – an amazing educational resource for bedside ultrasound, and the EMSONO: Ultrasound Test. It is also where we add our entries for their newsletter that goes over tips and tricks, cases, and all things ultrasound in the news. We recently wrote an article for the ACEP Ultrasound Section Newsletter – which is available for all members of the ACEP US Section – and I highly recommend becoming a member – it’s totally worth it.”

It was a TRUE pleasure to record a podcast recently with Dr. Scott Weingart (aka, my hero) on EMCrit (twitter: EMCrit), and writing this article with our ultrasound fellow, Dr. Viveta Lobo, describes some of what was spoken about.

By Viveta Lobo, MD and Laleh Gharahbaghian, MD, FACEP

As discussed in our last entry, the FAST exam is undoubtedly the most widely used bedside ultrasound application used in emergency medicine. Its incorporation in the ATLS revised protocol, the RUSH exam, and several other published protocols, makes it an invaluable screening tool for intra abdominal injury causing hemoperitoneum, cardiac injury with pericardial effusion, and unexplained hypotension.

We will continue our discussion of the FAST scan by reviewing the cardiac views, and relay some tips and tricks for each. Refer to the previous newsletter for tips onscanning the right upper quadrant (RUQ) and left upper quadrant (LUQ).

The Cardiac Views:

The traditional cardiac view obtained as part of the FAST exam is the subxiphoid view. The main focus of this view in the FAST exam is to evaluate for evidence of cardiac injury by evaluating for pericardial effusion and/or cardiac tamponade. The phased array probe is placed in the subxiphoid space medially, applying pressure to go under the xiphoid process and flattening out the probe while aiming caudally.

Tips for the Subxiphoid View: 

1. Use your liver as an acoustic window. 
Sound waves will travel through liver to the heart, allowing you to visualize the heart. Often one can even place the probe slightly to the right of the xiphoid process, to allow for better liver visualization, and then adjust your depth to be able to look past the liver to the heart. Without the liver in view, gas scatter will affect your image acquisition.

2. Visualize both the inferior and superior pericardial borders, to completely evaluate for pericardial effusion or, rarely, loculated pericardial effusions. It is possible for one area to have pericardial effusion and not the other. Click Here for a Video.

3. Have the patient take a deep breath and hold it. When you notice that the heart is far from the probe, and you find yourself adjusting your depth to more than 20cm, having your patient take a deep breath will lower the heart closer to the probe, improving visualization. Click Here for a Video.

Despite the subxiphoid view being the traditional view for the FAST exam, the parasternal long view is becoming more of the ‘go-to’ window to evaluate for pericardial effusion. This may be due to several very relevant clinical factors: You simply cannot get a good subxiphoid view. An injury, foreign body, or abdominal pain does not allow for subxiphoid probe placement/pressure. Or you can differentiate pericardial fluid from pleural fluid in the parasternal long view. 

Tips for Parasternal Long View:
As far as patient positioning, if you’ve already evaluated the RUQ and LUQ (so as to not affect free fluid evaluation) and the patient is able to turn into a left lateral decubitus position, it will help bring the heart closer to the chest wall for visualization. This can be difficult, or impossible, in trauma patients, so the below tips may help:

1. Start high and start medial – Place your phased array probe just next to the sternum, starting just under the clavicle. If you don’t see the heart there, slide down a rib space, and fan through that space to find the heart. Continue sliding down rib spaces, until you find it.

2. Slowly change the angle of your probe (up and down) when you’re assessing each rib space as described above. ‘Slowly’ is the key word here. If you’re angling downward too much in a rib space and see the PSL heart, you may need to just slide down a rib space. If that makes the image worse, slide back up.

3. Slowly rotate your probe while keeping the angle described above (clockwise/counterclockwise depending on whether you use the right shoulder or the left hip to direct your probe marker). Rotate until you visualize the longitudinal view of the left side of the heart.

4. Slide your probe medially/laterally only if you need to in order to center the aortic and mitral valves on your screen.

5. Ensure adequate depth in order to distinguish a left sided pleural effusion from a pericardial effusion. This will allow visualization of the descending thoracic aorta seen in its transverse view just deep to the heart, which is your landmark in differentiating pleural effusion from pericardial effusion. Pleural effusion will travel posterior to the aorta while pericardial effusion will travel anterior to it (and possibly circumferentially around the heart).

Lastly, it can be very difficult in both subxiphoid and parasternal long views to differentiate epicardial fat pad from pericardial effusion. One tip: epicardial fat is seen anteriorly and has echogenicity within it, while pericardial effusion is seen posteriorly or inferiorly and is anechoic, but can travel anteriorly if large enough to become a circumferential pericardial fluid collection. Despite this tip, clinical correlation is needed.

Look out for Part 3 of the FAST Exam: The Pelvis, in the next newsletter. Until next time, happy scanning!

For a set of links to online education in bedside ultrasound, go here. Another post on Social Media in EM Ultrasound and the amazing tools out there to learn it for free, go here.”

References
1. Ma OJ, Mateer JR, Ogata M, et al. Prospective analysis of a rapid trauma ultrasound examination performed by emergency physicians. J Trauma. 1995; 38:879-85.
2. Wherrett LJ, Boulanger BR, McLellan BA, et al. Hypotension after blunt abdominal trauma: the role of emergent abdominal sonography in surgical triage. J Trauma. 1996;41:815-20.
3. Schiavone WA, Ghumrawi BK, Catalano DR, et al. The use of echocardiography in the emergency management of nonpenetraing traumatic cardiac rupture. Ann Emerg Med. 1991;20:1248-50.
4. Rozycki GS, Feliciano DV, Ochsner MG, et al. The role of ultrasound in patients with possible penetrating cardiac wounds: a prospective multicenter study. J Trauma. 1999;46:543-52.

 

 

 

SonoTutorial: The FAST Part 2b: Left Upper Quadrant – More images that could fool you…

Get ready for some more real cases and, just like the prior post, with images of various sections of the left upper quadrant (as you cannot really have all sections in only one 6 second clip). Just like before, think of what is needed to complete the left upper quadrant view:  read the clinical correlate, see the image, and think about what section of the left upper quadrant view is missing (above the diaphragm, below the diaphragm, between the spleen and superior pole of kidney, between the spleen and inferior pole of kidney, or the paracolic gutter), how the image could be improved, and what the interpretation would be. All are stated below the image as well as the actual diagnosis of that particular patient. And, in case any of the below cases stump you as to why the FAST is negative or why it was done in the first place, recall its indications and…. Don’t forget the FAST limitations.

SonoTutorial: The FAST Part 2a: Left Upper Quadrant – Images that could fool you…

Get ready for some cases!!! The images and clips below will be a great review to see how much of the information from the prior post on how to perform a complete left upper quadrant view of the FAST scan you recall, while keeping FAST limitations in mind. Remember, in order to be complete and thorough you must evaluate above the diaphragm, below the diaphragm, around the spleen and superior pole of the kidney, and around the spleen and inferior pole of the kidney, and along the left paracolic gutter –  through slow, deliberate, and full fanning between multiple rib spaces, and adjusting your depth as needed.

The images will appear with a clinical correlation first which may give you a certain level of suspicion. Think about what part of the LUQ scan is missing (as there is very few times when you can get all of the above areas in just one clip or in just one rib space), how would you improve the evaluation (changing position of probe, fan more widely or slowly, depth or gain (brightness) adjustment, etc), and what your interpretation of that image would be (positive or negative for free fluid – or is the image just too technically limited to make a statement on it?)- all while thinking of your level of suspicion of injury given the clinical correlate.

These are all real cases:

SonoTutorial: The FAST Part 2: Left Upper Quadrant – being right with the left…

No, this isnt a talk about partisan politics (thankfully!), but something that is even more important that you should know and learn well, that could not only change everyone’s life [like politics thinks it does] (by way of how they manage their patients) but also saves a life (by how quickly you help your diagnoses be made). That’s right fellow blogosphere friends. Listen up!

Our SonoTutorial on The FAST: Right Upper Quadrant (RUQ) week was just the beginning of this review on the FAST scan- the most common application done at the bedside at many institutions, and for good reason. It’s used (as a screening study for intraperitoneal free fluid) for any blunt or penetrating chest/abdomen/back trauma as well as the unexplained hypotensive patient (the RUSH exam). The RUQ is the best area to evaluate for free intraperitoneal fluid of all the FAST views, but don’t think you can just do that view and stop there! It is not 100%, and there are enough times for me to see free fluid in the left upper quadrant (LUQ) that was difficult to see in the RUQ that makes it evident that completing the FAST scan is key! The LUQ is, essentially, the not-so-ugly sister to the RUQ.

SonoTutorial: The FAST Part 1b: The Right Upper Quadrant: More images that could fool you

Get ready for some more real cases and, just like the prior post, with images of various sections of the right upper quadrant (as you cannot really have all sections in only one 6 second clip). Just like before, think of what is needed to complete the right upper quadrant view:  read the clinical correlate, see the image, and think about what section of the right upper quadrant view is missing (above the diaphragm, below the diaphragm, between the liver and superior pole of kidney, between the left heptaic edge and inferior pole of kidney at the paracolic gutter), how the image could be improved, and what the interpretation would be. All are stated below the image as well as the actual diagnosis of that particular patient. And, in case any of the below cases stump you as to why the FAST is negative or why it was done in the first place, recall  it’s indications and…. Don’t forget the FAST limitations.

SonoTutorial: The FAST Part 1a: The Right Upper Quadrant: Images That Could Fool You

Now the fun starts! The images and clips below will be a great test to see how much of the information from the prior post on how to perform a complete right upper quadrant view of the FAST scan you recall, while keeping it’s limitations in mind. Remember, to be complete and thorough, you must evaluate above the diaphragm, below the diaphragm, around the liver and superior pole of the kidney, and around the left liver edge and inferior pole of the kidney (along the right paracolic gutter) through slow and deliberate full fanning between multiple rib spaces, and adjusting your depth as needed.

SonoTutorial: The FAST Part 1: The right upper quadrant – the right way to do it

The FAST scan (focused assessment with sonography for trauma) is probably the most frequent application of bedside ultrasound with a moderate sensitivity and very high specificity. It is done as part of our trauma evaluation for blunt or penetrating chest/abdomen/back/pelvic trauma as well as in the evaluation of the unexplained hypotensive patient as part of the RUSH protocol and the patient with a possible ruptured ectopic pregnancy.

SonoApp: Lung Ultrasound – The down low of pneumo…with the help of Lichtenstein, of course

Lung ultrasound (aka thoracic US) is one of the currently most popular applications of bedside ultrasound. It was found to be more sensitive and specific than chest XRay for pleural effusion, pulmonary edema, and pneumothorax evaluation (see meta-analysis in Chest here)…. how about them apples?! There have been some recent studies suggesting that in the heat of the moment for trauma patients, the sensitivity may be slightly lower than other studies state, but it is still better than chest Xray! Not only does it take a long time to get that chest Xray done in your ED or in through your ambulatory care practice, but its more expensive than bedside limited ultrasound for the patient as well…. lets not even talk about the radiation (yes, I know, Chest Xray radiation is minimal, but it’s still radiation). The evaluation of the lungs takes no more than 3 minutes, and ultrasound machines can be found in your pocket now (should you want that kind of VERY COOL technology). US machines can also be the size of a laptop with better resolution and multiple probe capabilities – so, needless to say, its easy, portable, fast, and more accurate. Now let’s talk…

SonoCase: Motorcycle victim: needs OR! But wait…

So, this case that I just had the other day is an example of an “oldy but goody” reason why bedside ultrasound rocks, especially in the blunt trauma victim with multiple injuries. 40 year-old motorcycle helmeted driver going moderate speed was T-boned by a car and fell onto his left side. He c/o severe left leg pain and mild left lower back pain, with STABLE (and yes, I mean, stable/normal/not worrisome vitals – HR 72, RR 16, BP 148/90, O2 sat 97%RA) with a clear primary trauma survey, and a secondary that revealed a small abrasion on his cheek, no left sided chest wall tenderness, nontender abdomen, no pelvis instability, an obvious deformed open fracture of his left tibia/fibula, and left lower posterior rib cage tenderness without crepitance or bruising. An E-FAST was done…