Errors in Gallbladder Ultrasound - SD

Introduction

Hi, I am Cheryl Kirby and I'm from Albert Einstein Medical Center in Philadelphia.

And I'm going to speak on errors in gallbladder ultrasound.

My interest stems from being an attending for 17 years and over the time, evaluating pitfalls or potential pitfalls in ultrasound.

Hi, I am Cheryl Kirby from Albert Einstein Medical Center and I've come to talk to you about errors in gallbladder ultrasound.

Why Study Errors?

The reason is to maintain high level of care, especially in today's environment of increased productivity with less time for hands-on scanning.

We have a residency program at our institution and we have residents who scan at night, but now also there's another group of doctors performing these studies and those are the emergency physicians.

The American College of Emergency Medicine actually credentials their physicians for emergency right upper quadrant ultrasound after performing 25 to 50 studies, whereas the American Institute of Ultrasound and Medicine recommends 300 studies before interpreting.

Now the emergency physicians are scanning to evaluate for stones.

Learning Objectives

The learning objectives for this lecture is to evaluate methods to help decrease technical errors when looking at the gallbladder.

Recognize the importance of visualizing the gallbladder neck, separate normal structures and physiologic changes from actual gallbladder pathology.

Differentiate the gallbladder from other fluid-filled structures.

Recognize causes for non visualization of a fluid-filled gallbladder.

Distinguish between various etiologies of non-dependent echogenic foci in the gallbladder and review biliary and systemic causes for gallbladder wall thickening.

Conflicts of Interest

And I have no conflicts to disclose when looking at the gallbladder.

We primarily look at gallstones or gallstone related complications.

An ultrasound has a high accuracy for diagnosing gallstones, and here we have an image of the gallbladder.

It's not with the most up-to-date machinery, but still we can see the distended gall bladder with these focal echogenic areas and shadowing, representing gallstones.

That was easy.

Okay, that can be easy.

Let's look at this patient.

This patient also has gallstones where you see echogenic areas with distal shadowing as well as fine internal echoes in a distended gallbladder.

The stones and the sludge were seen on the ultrasound.

However, what was missed are these linear echogenic regions that project intraluminal, which actually represents SLT mucosa in this patient with gangrenous cholecystitis.

This patient was sent home but luckily returned the next day without perforation.

So maybe it's not so easy.

Types of Errors

We're gonna discuss three types of errors, technical errors, anatomic errors, and diagnostic errors.

Technical Errors

Let's start with technical errors.

They're related to the choice of equipment and the performance of the study and I think they account for false negative diagnosis of stone disease.

In this patient there are focal echogenic regions seen with which do not shadow.

The study was performed with the curved five two megahertz transducer.

Now how are we gonna optimize this image?

We're going to increase the resolution by moving to a higher resolution transducer, a curved seven four megahertz transducer, a higher frequency, and we're gonna put the harmonics on, which also use the higher frequencies.

If we don't have shadowing, we can turn the compound imaging off, which will eliminate scanning from different directions, those multiple beams and scanning just from superiorly and we can adjust the focal zone.

And in doing so, now we develop, now we see posterior acoustic shadows from gallstones and not just sludge.

This is another patient who had right upper quadrant pain.

That patient was scanned by the resident at night and the resident noted that the patient had a positive sonographic Murphy sign.

Why is this study limited?

It is limited because the gallbladder neck is not included in the study.

So the patient was brought back down the following morning and here you can see a stone impacted in the region of the gallbladder neck in this person with acute calculus cholecystitis.

So the learning point is we must see the gallbladder neck.

And here let's look at the anatomy.

We have the gallbladder neck, the body, and the fundus of the gallbladder.

The neck is almost always located in the inter lobar fissure where the body and fundus can vary in location.

So on the CT scan with in a patient with gallstones, we see the stone in the region of the gallbladder neck located in the inter lobar fissure region, whereas the fundus is actually projected behind the kidney.

So the fund dislocation can vary.

So bottom line is remember the neck, but don't forget the other end.

Now in this patient we see pericystic fluid deep to the gallbladder.

In the gallbladder we see sludge.

It's true that the neck is not included on this study.

However, we wanna evaluate the cause of this pericystic fluid.

Is it related to an adjacent organ or a systemic cause or is it related to perforation of the gallbladder?

When looking for perforation of the gallbladder, make sure to look in the region of the fundus because perforation frequently occurs in the region of the fundus.

And sure enough, on the sagital image of the gallbladder you can see discontinuity of the gallbladder wall with this pericystic fluid.

This discontinuity is actually better seen on the transverse image here There is sludge or debris within the gallbladder.

Note the gallbladder wall discontinuity right here with this material extending deep to the gallbladder on real time imaging.

We pressed on this region and actually received a little flow, caused by movement of the material through the hole in the gallbladder wall.

But we wanna differentiate a perforation of the gallbladder fundus from a normal finding theary in cap.

And what do we have for the Fr end cap?

We see this nipple like area of fluid extending off the fundus.

Now in a fr end cap, there is continuation of the gallbladder wall around this area, around this nipple like area.

Now what do we have on our perforated patient?

Well here, there also there's discontinuity of the wall and you do not see continuation of the wall around this fluid.

So one should not confuse the perforation for the normal fringing cap.

So let's discuss the sonographic Murphy sign.

When discussing technique on how to perform the gallbladder, what is the sonographic Murphy sign?

One is ma, the Sonographic Murphy sign is maximal pain elicited over the sonographic localized gallbladder.

When do we have a negative sonographic Murphy sign?

One if there's no pain, two, if there's diffuse pain or three if there's pain located distant to the gallbladder.

Dr. Brie reported a sonographic Murphy sign as being 86% sensitive for diagnosing acute cholecystitis.

So this is an important sign.

Now much of the current literature and gallbladder ultrasound is actually in the emergency literature and doctors Kendall and Shemp reported only a 45% sensitivity in diagnosing a sonographic Murphy sign when performed by radiology as opposed to 75% sensitivity when performed by the emergency physicians and thus improved sensitivity in when emergency room physicians diagnose for acute cholecystitis.

Their proposed difference is related to radiologists not performing the study but reading hard copy.

That is food for thought.

So there are a couple recommendations.

Number one, if there's disparity between the appearance of the gallbladder and the reported sonographic Murphy sign, we should bring the patient back and recheck the patient.

Number two, the proposed difference is related to radiologists not performing the study but reading the hard copy while someone's performing the study.

There either are sonographers or they're residents and it's imperative upon us to teach these people how to perform the Sonographic Murphy sign.

I find that especially starting out in training and starting your scanning, sometimes people are afraid to actually press on the area that hurts.

And pressing an ultrasound is imperative when diagnosing and evaluating the gallbladder or the appendix, even examining the patient's, the patient's pelvis.

If you see the, let's say you see the ovary and you're not, it's in the periphery of the image, you just have to press a little bit more to really get it in.

Pressing is very important and we have to explain to the sonographers and the residents that pressing down in the area of hurt that hurts is important.

Number three is frequently people say that, I couldn't assess the Sonographic Murphy sign because the patient received analgesics in the emergency room.

Nelson et all did a study and reported no difference in the sonographic Murphy sign sensitivity after opiate administration.

And we have seen the same in our practice.

Even though the medicines may take the edge off the patient's pain when you press, it still hurts them as long as they're not sleeping.

So key points to remember.

And in order to decrease the technical errors, use the highest resolution transducer permitted for the depth of the gallbladder.

Use harmonics, move the patient in different positions.

We didn't have time to talk about that, but typically the sonographers will examine patients in the supine and left lateral decubitus.

But we can also move the patient in the right lateral decubitus or sit the patient erect scan.

Both ends look at the neck, the gallbladder neck, and the gallbladder fundus and have a low threshold for checking for sonographic Murphy sign.

Anatomic Errors

Let's move on to anatomic errors.

Those are related to normal structures, variants and physiologic changes that may be misinterpreted as disease processes.

And I think they account for false positive errors.

Well, here we have a contracted gallbladder.

And is this abnormal true or false?

No, this is not abnormal.

This is a normal gallbladder that we brought back several hours later in a patient who actually had eaten prior to the study.

So they ate here, it had, they had physiologic contraction of the gallbladder and then came back a couple hours later for a nice normal exam.

And I tend to ask the patient in a non-confrontational way if they've eaten, as opposed to looking at them harsh and saying, have you eaten?

I usually say, gee, what'd you have for breakfast?

And frequently I get a litany of egg bags, eggs, bacon, et cetera.

Or sometimes patients will say, oh no, doctor, I, I haven't eaten since, since last night.

So that's a non-confrontational way of asking someone, what is causing this shadowing in this patient?

Here we see the gallbladder here and then we have this echogenic region with pretty dense shadowing where this actually is adjacent bowel mistaken, initially mistaken as stones.

And we see this several times a year.

Now bowel frequently may have hazy posterior shadowing, which may help.

This actually looks pretty dense, so this might be difficult to assess.

But frequently when you change the patient's position, the bowel may change in configuration and you can really see here that this is outside, this is extra luminal, not within the gallbladder.

This study, this area was preliminarily read as a thick walled gallbladder.

Well, why is this wrong?

Well it's not, it's located in a pretty good location.

Here's the left lobe of the liver.

You can see the falciform ligament.

So it's near the inter lobar fisure.

But the reason this is wrong is because this has this, this is bowel and this has the typical sonographic bowel signature where you get bright and dark layers.

How many layers you see depends on the resolution of the scan and how deep you are.

But you should at least see these inner bright mucosal layers and the outer muscularis layers.

So when looking at the bowel, we should Beware of the bowel.

Yes, the bowel can have several appearances.

It can look fluid filled like the one we just saw, which could be mistaken as a thick wall gallbladder perhaps it's filled with air, it's air filled and you see it's increased echogenicity.

And here this has hazy shadowing.

Don't mistake that for a stone filled gallbladder or perhaps the bowel has fluid and debris and could be mistaken as a distended gallbladder with stones and sludge.

Let's look at this case.

This was read as a gallbladder with stones and sludge and here we do have an echogenic area with shadowing as well as layering debris.

Well, two weeks later the patient came back for an unrelated ultrasound and this was the appearance of the gallbladder.

Well, what's the reason for the change in appearance?

The reason is that this is the stomach, this is not the gallbladder.

And how can we tell?

Well look at that, that classic bowel wall signature here we see dark, bright, right?

So don't confuse that for the gallbladder points to, methods to decrease anatomic errors will understand the normal fold.

So as not to confuse them with pathology such as the PHN and cap.

Do not confuse non-fasting contracted gallbladder.

For for pathology, be aware of edge and side lobe artifacts and familiarize yourself with the many appearances of the bowel.

Diagnostic Errors

And now we're gonna go on to diagnostic types of errors, errors of interpretation.

And I have divided these into four categories.

Misinterpreting the fluid-filled structures for gall for the gallbladder, the non visualized fluid-filled gallbladder, adenomyosis and gallbladder wall thickening.

Misinterpreting Fluid-Filled Structures for the Gallbladder

So misinterpreting fluid-filled structures for the gallbladder.

One is we can see bowel, which we've talked about, two abscesses cysts in adjacent organs.

Perhaps the patient has had their gallbladder removed and has fluid in a cystic duct remnant, they could have a mucus seal or perhaps there's inflammatory response with fluids surrounding drop stones from prior cholecystectomy or even dilated vessels.

So let's look at this case.

Oh my goodness, look at this person.

This person has autosomal dominant polycystic renal disease and also has hepatic cysts and there are multiple fluid-filled structures in the liver.

Wow, someone looks at this and may wanna scream 'cause how do you figure out what the gallbladder is?

Well, don't scream because we know where to find the gallbladder neck in the inter lobar fissure.

And that will help us decide which one is the gallbladder.

This happens to be the gallbladder.

How about in this patient?

This was preliminarily read as a gallbladder with gallstone and you do see fluid with focal echogenic areas in shadowing.

But when we went to check the per person in the inter lobar fissure, we saw a contracted gallbladder with stones.

So what was the cause of this fluid collection?

Well, it's related to a peri hepatic abscess from a, a perforated duodenal ulcer.

Here it is.

And there's another here.

Now let's look at this patient.

This is someone who's had a cholecystectomy five months ago for a gangrenous perforated gallbladder, and now comes in with recurrent right upper quadrant pain.

What are the findings?

Well, we do see fluid in the region of the gallbladder fossa and there are these focal echogenic areas with shadowing.

Here we can see the stones.

So these look like stones.

Look at the, the area of the wall.

The wall is thickened and irregular and if you didn't, did not have the history of prior cul the cystectomy, you may think that this is a chronically inflamed gallbladder.

Well, wouldn't we look silly if we dictate inflamed gallbladder, chronic cholecystitis and someone and we get a phone call from the surgeon or the physician saying, excuse me, five months ago this patient had their gallbladder removed.

Well, what this is is this is an inflammatory response around dropped gallstones.

Sometimes it's hard to tell if patients have had prior chole cystectomy, especially if they've had laparoscopic chole cystectomy and can't tell you such.

So, it is important to have the history non visualization of a fluid-filled gallbladder.

Non-Visualization of a Fluid-Filled Gallbladder

We can have a gallbladder filled with stones.

We might have air within the lumen of the gallbladder caused by either infection such as emphysematous, cholecystitis prior surgery, or a fistula formation between the gallbladder and the bowel.

Perhaps there's air or calcium in the gallbladder wall that's preventing visualization of the gallbladder or maybe the gallbladder's removed either from prior cholecystectomy or rare gallbladder agenesis.

Well, here we have a patient, with a gallbladder filled with stones and the typical wall echo shadow sign.

Here we go.

Wall echo dense shadow.

Now this is a gallbladder filled with stones.

Don't confuse it for the bowel.

Here's again the bowel, the the air filled bowel, which can be confused.

Here's another patient who has dense sludge within their gallbladder.

And boy, it can be even hard to see to differentiate the gallbladder from the adjacent liver.

Now in this person the sludge actually is a little bit more echogenic, but we sometimes have to use this edge artifact to help locate the gallbladder.

Also note that there is a stone in the neck of this gallbladder.

This was a study, performed by a experienced one of my experienced stenographer who came out and said, gee, doctor, I, I scanned this patient.

I can see where I think the gallbladder is, but it's really hard to find it now why is that?

So we went back in to check and boy this does have a typical shape of a gallbladder, but there's this hazy shadowing in this lumen.

Well maybe this is gas or air.

Well we wanna make sure that we're not looking at bowel.

So we're gonna look at the wall just to make sure there's the no, make sure we do not see the bowel wall signature and we do not.

So there's concern that this is the gallbladder filled with air.

Well what are we gonna do?

Well if there's air, we're gonna turn the patient down, we'll turn the right side down so that the air will move up to the left and then we'll scan from the right.

And lo and behold, we did see fluid in a distended gallbladder.

Here's a confirmatory CT showing a large amount of, of air or gas in this gallbladder as well as air in the biliary tree.

This is someone who had had prior surgery, bowel surgery, but also had acute and chronic cholecystitis on a pathology report.

Non-Dependent Echogenic Foci

Now we're gonna look at non-dependent echogenic foci.

Well, not all non-dependent genic foci represent adenomyosis.

Adenomyosis is one of those fun words to say.

It's got eight syllables and people seem to grab onto it really early in their training.

But not every non-dependent echogenic focus is adenomyosis.

So what is adenomyosis?

Adenomyosis is basically a subset of chronic cholecystitis where one gets hyperplastic changes involving the gallbladder wall and can cause overgrowth of the mucosa, thickening of the muscular wall and formation of intramural diverticula.

Within these diverticula there may be cholesterol crystals that create this com tail artifact.

This person also has stones in the gallbladder.

Well here we have a case preliminarily red as adenoma mytosis.

And so what do we see?

We do see these focal echogenic areas in a non-dependent location.

There are, there are some artifacts off of these areas.

And what are we gonna do for further evaluation?

Well, let's move the patient and as we move the patient, these areas moved.

Hmm, well these represent either tiny stones or gas and I did call the physician the clinician, caring for this patient to discuss this patient who signs and symptoms were not, did not suggest inflammation.

We actually followed the patient clinically for over a couple days and re-scanned the patient in a couple of days and they did not have signs of infection.

So most likely these are felt to represent floating gallstones.

Here we have another case, preliminarily read as adenoma mytosis.

There are these focal non-dependent echogenic areas within the gallbladder, but when you look at these areas, these areas really look intraluminal.

They're not along the wall.

This is someone with floating gallstones who had a ct, several, who had a prior ct, which shows these floating gallstones in the gallbladder.

This gallbladder actually has some contrast in it because of vicarious excretion in a patient with renal disease.

Another case non-dependent echogenic foci in the gallbladder.

Hmm, these may represent floating stones, maybe their air.

The patient also had pain in their abdomen.

So we obtained a ct which shows that this actually represented gas in the gallbladder.

And when we look at the re at the remaining images, the small bowel is distended and the small bowel is distended secondary to a distal gallstone causing a, causing an obstruction.

This is the misnomer or gallstone ileus, which should really be called gall gallstone small bowel obstruction.

Another case preliminarily read is adenomyosis.

Here we see echogenic areas in the wall, some artifact.

And this is caused by calcification in the wall from porcelain gallbladder.

Gallbladder Wall Thickening

Well now we're going to briefly discuss gallbladder wall thickening.

There are primary biliary as well as secondary causes for gallbladder wall thickening.

In 1991, Dr. Tfi, I looked at the striated pattern of gallbladder wall thickening and was unable to and were unable to differentiate the primary from secondary causes unless there was acute cholecystitis.

Then there was concern for gangrenous cholecystitis.

The new literature on gallbladder imaging in the in the radiology literature concerns gallbladder wall enhancement patterns and thickness on CT or layering thickness on MRI and they found improved accuracy in differentiating benign from malignant causes of primary gallbladder wall thickening.

Perhaps there will be a role for ultrasound for ultrasound contrast in the future.

Well when looking at the causes we have primary causes such as acute and chronic cholecystitis, adenomyosis, gallbladder cancer and non and non-fasting gallbladder.

Or we can have adjacent inflammation in the organs adjacent to the gallbladder such as hepatitis, pancreatitis, causing wall thickening.

Perhaps there's, there's a problem with the patient's volume status, whether they have decreased plasma oncotic pressure or or increased extra axial fluid volume that can be causing gallbladder wall thickening.

There could be lymphatic obstruction related to tumor in the port he region or infections associated with AIDS mononucleosis, dengue fever that can cause gallbladder wall thickening.

So you see there are many causes of gallbladder wall thickening and based just on the wall thickening it is hard to make a diagnosis.

We really need to also look at the other signs and signs and symptoms.

So here's a patient with acute calculus, cholecystitis and there is thickening of the wall and we could either include this in the wall or this is adjacent edema, but the gallbladder is also distended intense.

There's a stone in the neck.

The patient had a sonographic Murphy sign.

These find other findings help us to diagnose acute calculus cholecystitis.

Here's someone with a contracted gall bladder with wall thickening and stoned in patient who had intermittent pain with chronic cholecystitis.

Another person with adenomyosis on a curved five two megahertz transducer.

This just looked like wall thickening, but on the high resolution transducer we can actually see small fluid-filled diverticula in this wall and are able to diagnose adenomyosis.

You can also see in this person has gallstones.

Now here are some secondary causes that we really need to use.

Ancillary findings.

This is a patient with a cirrhotic liver ascites accounting for this gallbladder wall thickening.

This person, however, also did have some sludge in their gallbladder.

Oh, here's a typical patient with hepatitis where a very small lumen and wall thickening patient with pancreatitis and we do see adjacent wall thickening.

It would be difficult to, differentiate this from other causes.

And a patient with aids who had wall thickening related to the infection.

This is someone who has congestive heart failure, did not have any signs or symptoms of primary biliary disease, but does have gallbladder wall thickening.

And we can see on CT that there are bilateral pleural fusions and some subcutaneous edema supporting the congestive heart failure diagnosis.

What's the etiology for gallbladder wall thickening in this patient?

Well, we did put color imaging on and you can see that there is vibrant color within this gallbladder wall, which is thickened because of gallbladder varis from portal vein thrombosis and cavernous transformation of the portal vein.

Main Teaching Points

So main teaching points, there are really three main teaching points.

Number one, you must visualize the gallbladder neck.

If the gallbladder neck is not included, then the study is limited.

Number two, beware of the bowel.

Don't forget to look at the bowel, know the different appearances of the bowel so that when we're looking at the gallbladder we can distinguish adjacent bowel.

Number three, the sonographic Murphy sign.

It's very important if there, if someone shows you an image.

And this discrepancy with the appearance of the image and the report of the sonographic murphy sign, it behooves us to check, to check the patient ourselves and teach the sonographers, teach our residents how to perform the Sonographic Murphy sign so that they can also perform the Sonographic Murphy sign.

Thank you so much for your time.