Gallbladder wall thickening

The normal gallbladder wall should measure less than 3-4mm. It is recommended that this measurement be taken through the anterior wall of the gallbladder, since posterior acoustic enhancement will often make posterior measurements inaccurate. The image above was taken in a patient with cirrhosis, chronic ascites, and no acute complaints of upper abdominal pain. While a thickened gallbladder wall is one sign of cholecystitis, there are a number of normal and pathologic states which can lead to this finding as well.

  1. Normal contracted gallbladder
  2. Hypoalbuminemia
  3. Alcoholic liver disease
  4. Increased portal venous pressure
  5. Acute viral hepatitis
  6. Heart failure
  7. Renal disease
  8. Ascites

Why does this occur? A normal gallbladder can exhibit a thickened wall of 4-5mm due to contraction alone. Typically this will occur in the setting of a lower-than-normal gallbladder volume.

For the rest, hypoalbuminemia is a major culprit in gallbladder wall thickening; alone or as a secondary mechanism in patients with cirrhosis, heart failure or renal disease. Other speculated mechanisms of gallbladder wall thickening in the disease states above are increased portal venous pressure and generalized edema. Going back through radiology journal articles older than the ones below (1970s-80s), the same mechanisms are invoked repeatedly, and other older articles are referenced. There seems to be no definitive mechanism proven to cause the gallbladder wall thickening, though many articles demonstrate that it does in fact occur, and distinct from incomplete contraction of the gallbladder itself.

Gallbladder wall thickening is often evident in adenomyomatosis and gallbladder cancer as well. In these settings the gallbladder wall diameter is directly a part of the pathology, and not a side effect of some other process as in the cases above.

Thus, this finding is not specific to acute cholecystitis. It is present in many other disease states and may even signal the clinician that there is some other pathology at play.

References:

  • Wegener M, Borsch G, Schneider J et al. Gallbladder wall thickening: a frequent finding in various nonbiliary disorders–a prospective ultrasonographic study. J Clin Ultrasound 1987 Jun;15(5):307-12. (PMID: 3149957)
  • van Breda Vriesman AC, Engelbrecht MR, Smithuis RH et al. Diffuse gallbladder wall thickening: differential diagnosis. Am J Roentgenol 2007 Feb;188(2):495-501. (PMID: 17242260)

 

Effusion

Ultrasound is quite sensitive in detecting even very small pleural effusions; it has been demonstrated to perform better than chest x-ray and nearly as well as CT scan. In order to assess for pleural fluid, the transducer should be directed through the liver (Right side) or spleen (Left side) and diaphragm. In a normal thorax, a mirror image artifact will generally be seen above the diaphragm. When effusion is present, fluid eradicates this artifact, creating an anechoic appearance in the costophrenic angle.

The image above demonstrates a common pitfall in abdominal and thoracic ultrasound. The liver is visible in the near field, and a dark anechoic structure is evident just deep to the liver. Some see this fluid and may note a positive FAST examination or free intraperitoneal fluid. Others may see this appearance and diagnose pleural effusion or hemothorax. While it is true the anechoic area represents fluid, there is a more correct response.

The inferior vena cava can generally be seen posterior to the liver, towards the patient midline. As it is filled with blood it will appear anechoic. below the diaphragm it will course parallel and to the [patient’s] right of the Aorta. Just above the diaphragm it will quickly merge into the Right Atrium.

As with most scanning, fanning through multiple planes will generally sort out the true anatomy. In the clip below we see the IVC as the operator sweeps medially, and the the pleural effusion is more evident in the lateral portions of the sweep. One (of many) giveaways is that the hepatic veins drain into the IVC, and even in this brief sweep through the IVC a hepatic vein is visible anteriorly, draining into the IVC.

Pleural effusion and mimic from Sinai EM Ultrasound on Vimeo.

ACEP US Section Discussion Forums

If you aren’t a member of the Ultrasound Section or ACEP this is a great reason to become one.

 

 

Mike Stone with help from Phil Perera and no doubt others have built a forum where you can find all of the most pertinent discussions from the section list-serve. There are a few choice topics available for your perusal and comment right now, but I’m sure this will be built into an even better resource in the future. Great Job.

 

To find the forums, head to the acep ultrasound section page and look for “ultrasound forum”.

The FALLS-protocol

In critically ill septic shock patients, assessments of hemodynamic function, fluid status and improvement of clinical status are challenging.  As a consequence of critical illness and large volume administration of crystalloids as recommended by Early Goal-Directed Therapy, comes the potential of acute (respiratory distress/failure) and long-term sequelae  (ARDS, prolonged endotracheal intubation, anasarca, bedsores, poor IV access, increased resource utilization).

The FALLS-protocol, developed by Daniel Lichtenstein introduces novel clinical parameters useful in the assessment of fluid status dynamically.  It aims to define the critical point when fluid administration is becoming deleterious to the patient (lung saturation), and we must start considering the use of vasopressors as well as the potential for respiratory failure.

Review: Lung Ultrasound basics

Utilizing a decision tree that obligates several simple cognitive and sonographic steps in the evaluation of shock, the true protocol begins when septic shock remains the most likely etiology and resuscitation has already been initiated.  By evaluating the lung parenchyma at the Blue Points, we begin with the A-profile in healthy patients.  Patients with fluid overload however demonstrate a B-profile (lung rockets emanating from the pleural line) indicative of interstitial edema.  In combination with vital signs, as we are administering fluids, we can evaluate the profile in either intervals of time or fluid aliquots.  At any of these intervals, if the patient remains hypotensive but has an A profile, we can feel confident that we can continue to administer fluids with little risk for respiratory compromise.  However, if the profile transitions to B-profile, we must consider vasopressors and advanced airway management.

Fluid administration is often guided by clinical judgment, with no clearly defined end point other than a normalized blood pressure. However, blood pressures can be corrected by vasopressors and are often given as a last ditch effort.  With the current emphasis on sepsis management in the US, EDs are coming under scrutiny for our role.  Although the FALLS-protocol still requires exhaustive study, it has the potential to allow a more finessed management of acute circulatory failure.

Reference:

Lichtenstein, D.  (2010) Wholebody Ultrasonography in the Critically Ill.  London: Springer-Verlag Berlin Heidelberg

Fluid Administration limited by lung sonography: the place of lung ultrasound in assessment of acute circulatory failure (The FALLS-protocol).  Expert Rev Respir Med. 2012 Apr;6(2):155-62.

 

Sonocloud

On July First, while most of us were busy meeting new interns, Mike and Matt from the ultrasound podcast along with Mike Stone have released into the wild their newest creation, sonocloud.

 

Sonocloud Logo
Sonocloud is awesome.  It is a copyright free compendium of all the clips you wish you had in your ultrasound quiver.  So next time you are a) putting a talk together and you can’t find you old clip of biceps tendonitis, or b) you get a really cool high quality clip yourself, head over to sonocloud to a) download an open-source clip or b) upload your own for others to use…

Top ultrasound scanning tips

Welcome new interns across the land! You will be receiving lots and lots of advice from many sources, so I’d like to pour some ultrasound scanning tips into the information deluge.

Most of these tips were posted here at SinaiEM.us a few years ago, yet they are so classic they they still ring true!

These are mainly directed towards novices, but there may be something useful in there for everyone to remember. Note that I used self-restraint and did NOT list “clean the machine” among the tips. I assume everyone has already built up an impressive list of excuses for not cleaning the machine. That sounds like another post in itself!

  • Start with one indication and become comfortable with it, then expand your repertoire
  • Before picking up the probe, think about how the results of the scan will change your management and clarify your clinical question (good advice for any diagnostic test)
  • Familiarize yourself with the most useful buttonsfirst (every machine has these):
    • Power, probe selection, depth, gain, save/print
  • Remember you are scanning three-dimensional structures- be sure to fan the ultrasound beam through several planes to visualize the full anatomy
  • Practice, and keep practicing. Ultrasound IS operator dependent, just like everything else you do in your practice. So get good at it, just as you became proficient in EKG interpretation or laceration repair.
  • When you can’t see anything:
    • Use more gel, find a better acoustic window, and check the common buttons (transducer, depth, gain)
  • Proper hand position is crucial- hold the probe so you are comfortable and stable
  • Check follow-up studies if they are performed, and compare your bedside results to CT scan, operative findings, etc.
  • Position the patient, the machine, and yourself for optimal visibility and comfort whenever possible
  • Share positive findings with your colleagues! Although pregnancies and gallstones are common, sharing aortic aneurysms or deep vein thromboses will be appreciated.
  • Share ‘saves’ with your colleagues! Although most applications for bedside ultrasound are evidence-based, never underestimate the power of the anecdote in changing practice patterns.

Please leave YOUR best scanning tip in the comments.

SAEM newsletter

The current issue of SAEM’s resident newsletter features an interview with Bret Nelson regarding ultrasound training. He and Beatrice Hoffman, MD, PhD, RDMS (Director of Ultrasound Education for the Department of Emergency Medicine at Johns Hopkins School of Medicine) are featured.

They describe their path towards emergency ultrasound, the value of fellowship training, advice for residents, the role of research, and more.