Ultrasound Guided Abdominal Biopsies: Lessons Learned - Part 1

Introduction

My name is Dr. Michael Hill.
I am a diagnostic radiologist from the Department of Radiology at the George Washington University Hospital in Washington DC.
And what I'm going to talk about today is the use of ultrasound in doing abdominal and pelvic biopsies.
Now, the way I do biopsies is probably different than the way you do it, but I'm gonna show you the way I do it and maybe you'll get something from that.
On the other hand, you may say, the way I do it is just as good, so I don't need your help.
Thank you very much.

So what I'm going to discuss is the use of ultrasound in guiding abdominal biopsies.
And this is basically what I've learned over the years and how I do them.
And as you're probably well aware, there are many ways to do a biopsy and you probably have different opinions, but I'll share mine with you during this lecture.
And by the way, I have no relevant financial relationships to discuss here.
I would like to address your attention to the ultrasound quarterly article published back in December, 2011, which does reflect the way I do my biopsy.
So that would be a back to this talk, which I'm about to give.

Patient Preparation and Coagulation Status

First of all, when we are asked to biopsy anything within the abdomen or pelvis, we generally would review the clinical history and obviously the medications the patient's on with specific reference to any medicines that might interfere with coagulation.
We also have a biopsy form.
We have our clinicians fill out to give us the full clinical information of each of the patients.
And following this, we will then review the imaging studies that are available.
The questions we then ask ourself is, or are, should I say, are the biopsy indicated?
Can I do it safely and should I use ultrasound or will I need ct?

In terms of the patient's coagulation status, we generally would do a hemoglobin hematocrit and platelet count, including a PTT PT and I, and or, and again, as I mentioned previously, we would also question the patient about anticoagulant medication.
Now, this is a very broad subject and unfortunately I do not have the time to discuss what we do in our department since every place has a different way of doing this.
Again, I would refer you to the ultrasound quarterly article of 2011 where we do state our policies.
Also, this article from a GR in 2009 is a very useful source where it does review the role of all of these factors when one is planning a biopsy in any given patient.
And so therefore, I would advise you to read this article.
So as you get some idea as to what other people do as well, obviously the risk of the biopsy is what's paramount in determining what you have to do.

If a patient is on anticoagulants, for example, we do thyroid biopsies with patients on all kinds of anticoagulants.
It doesn't really worry us, but when we talk about doing a biopsy on an organ such as the liver or kidney, well then we would want to have these coagulation.
We would want to know the coagulation status of the patient prior to proceeding.
Obviously, the risk of bleeding would be less as we go to doing lymph node biopsies or soft tissue masses and even lesser, so probably with doing a paracentesis or a thoracentesis.

Why Use Ultrasound Guidance?

Now, why do biopsies using ultrasound guidance?
Well, obviously we are in competition with ct and we would like to use ultrasound if at all possible since we have busy work days.
And therefore, as we well know, ultrasound is a much quicker technique in comparison to ct.
Not only that, but it is faster.
It is less expensive and portable.
Also, it's real time.
You can go in any plane you want using a five to 10 megahertz transducer, depending upon the depth of the structure to be biopsied.
However, as you well know, it's more operator dependent and does need a certain amount of skill.
We also are outta business sometimes because we cannot see the lesion due to bowel, gas or bone.
And in which case, a CT scan guided biopsy might be more appropriate.

Needle Techniques

In terms of whether we use a freehand technique or a guide.
Well, generally for small lesions that are superficial in location, we would tend to use a freehand technique.
And for more deeply seated lesions, we would use an ultrasound guide attached to the transducer.

In terms of what needles we use, well, first of all, doing cytology, we go anywhere from a 22 to a 25 gauge needle.
We generally do these, at least in my practice.
For cases where we suspect lymphoma to be on the diagnostic list, we will generally smear slides and put some into flow cytometry using or PMI medium, we will generally do at least three to four cytology aspirate.
We will have our pathologist present to give us an idea as to whether we're dealing with lymphoma or not.
Also, in some instances, we will use a coaxial approach.
That is where we will actually use a 17 gauge coaxial needle.
We will insert it down to the mass of the lymph node and then through that coaxial needle, we will actually put a second smaller cytology needle at a 22 or 25 gauge size and put it into the lesion.
We find this especially useful when we're biopsying deep lymph nodes because it does prevent the size of the 17 gauge coaxial needle does prevent the needle bending outta the field of view and makes it much easier to perform a cytological aspirate.

In terms of core biopsies, needles, well, obviously these are useful for obtaining histology, and we use these when we are looking at making a diagnosis of parenchymal disease, such as in the liver or the kidney, or diagnosing a liver or kidney mass or lymph nodes.
As I said already, we use a 17 gauge coaxial needle and a 18 gauge cutting needle, and we will use anywhere from one to four passes and obtain core biopsy tissue.
We can also vary the core length of the needle from anywhere from 1.3 all the way up to 3.3 centimeters, and I will show you where we use the longer 3.3 centimeter throw in just one moment.
The automated biopsy gun that we use is easy to handle, gives an excellent core of tissue, and it produces a core of tissue with no crush artifact.
Generally, we will put most of these core tissues usually onto formin.
However, sometimes when we are going to have the cytopathologist do a touch prep, we will actually put one onto a telfa pad, which is mo with non-static saline.
So it's to allow easy detachment of the specimen from that telfa pad.

And this is just an example showing you the automated biopsy gun that we used.
You can see the well of the needle where the core specimen is obtained, and then on the bottom right hand side, you can see an image of the core itself.
And on the left bottom side, you can see us shimmying the core specimen outta the well of the cutting needle.

Now, the advantage of using a coaxial needle, which I've become very fond of, is you use a single localizing pass and you can get multiple specimens by just inserting a second needle through the coaxial needle.
You can also sample different areas of tissue, but just by manually changing the angle of the coaxial needle.

Patient Preparation for Procedure

In terms of patient preparation, I personally no longer use conscious sedation.
I also do not have patients fast, and I also believe in the liberal use of local anesthesia, and I will use upwards of 30 ccs, which is the maximum dose of 1% lidocaine throughout the procedure.
I try to reassure the patient, of course, at the same time monitoring their pulse and blood pressure having obtained always proper informed consent, which includes describing the procedure.
Also, it's complications, including also the fact that sometimes we can't always expect to make a diagnosis using this technique.

General Procedure

In terms of the procedure itself, well, we basically, having gotten permission from the patient, we will scan the patient, we will then choose an appropriate site to enter the skin to get our tissue.
We will prep and drape that region, usually using either Betadine or some other antiseptic agent.
We will use ultrasound to guide the local anesthesia, and I will also use a three millimeter skin cut with the scalp blade to allow easy access of the needle through the skin.
And again, as I assessed already, we also can use a freehand or a sterile guide technique.

Now, visualization of the needle tip requires the highest frequency transducer that you can use, and we vary this usually from a five to seven megahertz transducer.
We obviously need to make sure we have the correct focal zone so we can see the needle tip, and sometimes the needle can be difficult to see, especially if the tissue is very echogenic, in which case, what I will do is I will rock the transducer back.
I'm sorry, I will rock the needle back and forth so as to visualize this tip.
I will also use color doppler, not only to visualize the tip itself, but also to avoid any intervening vasculature between the skin and the site of biopsy.
I like to make a skin wheel using about two to three ccs of 1% lidocaine intradermally.
I like to use a three millimeter skin nick with a scalpel, because this allows easy insertion of the needle.
It will also allow you to feel the texture of the tissue you are going through.
And as you know, a metastatic lesion in the liver is much tougher than the normal liver itself.
So in this sense of feel can be especially useful with small lesions in the liver.

Okay, I'm ready to go again.
Okay.
The reason why I like to use local anesthesia along with ultrasound to get down to the organ to be biopsied, is that you can actually see when you are entering into the muscle of the patient's abdomen.
Now, as you probably are well aware, once you've numbed up the skin in the first centimeter so of soft tissue fat, it doesn't really hurt the patient to go through the fat itself, but where it starts to hurt is when you enter into the muscle of the patient's abdominal wall.
When you enter this portion of the abdominal wall, you should give the patient a warning that this will hurt.
I also like to be able to insert my needle all the way down to the organ I want to biopsy.
So I can put a layer of local anesthesia on top of, and in this instance, this is the liver.
So we would put a layer of a couple of ccs of local down at this surface of the liver.

Liver Biopsies

For doing liver biopsies, we're obviously looking for either getting a piece of the parenchyma to evaluate for parenchymal disease, or we're going to be going after a mass to diagnose either hepatocellular carcinoma or metastatic disease.
In doing the biopsies for parenchymal disease of the liver, I usually like to go in the supine midline subcostal approach into the left lobe of the liver.
If the patient has a very small left lobe of liver, well then it may not be possible, and you may have to put the patient in the left decubitus position and use an intercostal approach.
I personally don't like to use this approach because this approach hurts much more than going through the subcostal midline approach.

Here we have an example on the left of using a 23 gauge millimeter throne needle.
And as you can see in this instance, when you can see the needle go into the liver and you can see that how far it goes down.
In the old days, I used to do two biopsies like this, but then I went and used a 33 millimeter throne needle.
And when you do a biopsy with this, you see you get a much deeper cord of tissue, and you need only do this once.
So that's why I like the deeper throne needle.

When I am going after a biopsy for parenchymal liver disease, When I wish to biopsy a mass within the liver, I use a coaxial needle.
I bring the needle tip down to the mass, and I like to insert this needle through a cuff of normal tissue.
And I explained why in just a moment.
If the mass is very large, I will biopsy the outer margin.
If it's a small, smaller mass, I will just go through the center.
Obviously in a larger mass, if one heads towards the center right away, you may just get back necrotic tissue.
So we don't want that.
So having once got the coaxial needle into place, I insert the cutting needle through the coaxial needle down to the mass.
I then will suspend respiration and then I will fire off the needle and withdraw.

In this instance here we have a patient with the history of metastatic breast carcinoma, who has a small mass lesion in the liver here, and we're trying to make the diagnosis of whether this is a metastatic lesion.
And image on the left here, I did a fine needle aspiration again by inserting the quain needle in to the mass and then doing my fine needle aspirations here.
And then I follow this with two core biopsies, again, using the quain needle as my guide, just emphasizing the use of the coaxial needle as allowing you to take as many biopsies as you wish with just one insertion of the needle.

This is a patient with lymphoma, again, with a small lesion in the liver as we can see here.
And then when we go to here, you can see the coaxial needle is here, and then you can see the fine needle being inserted through the coaxial needle to take a biopsy from this lesion proving that this was in fact lymphoma.

Now there's always been a debate about whether you can do a core biopsy of the liver when there's a lot of ascites, and it's been well shown that the risk in doing a core biopsy is no greater, whether you have ascites or not, it can be technically more difficult because of the fact that if you have a cirrhotic liver that is somewhat hard with a lot of ascites, it can be hard to get the biopsy needle into the liver.
But even so, I rarely have to withdraw ascites to do this kind of biopsy any longer.

Now, this is an example of a vascular mass in the liver in a patient who has a cirrhotic liver in ascites.
And here we have our ultrasound here showing the mass within the liver.
And here we have our biopsy here.
As you can see, again, I put a coaxial needle through the liver down to the level of the mass.
And then through that I've taken my core biopsies to prove that this patient did in fact have hepatocellular carcinoma.

Now, I don't like the biopsy lesions on the surface of the liver because of the fact, especially if they're vascular, they can bleed.
And in this example, this was an HIV positive individual with hepatitis B with a cirrhotic liver and a vascular mass, very suspicious for hepatocellular carcinoma.
So I went ahead and did my biopsy, and then following the biopsy, lo and behold, the patient bled, as you can see here, there's some blood off in the acidic fluid at this point, and obviously this demand that then he had to be embolized following this biopsy.
So I learned a lesson from this not to biopsy vascular lesions on the surface of the liver.
If at all possible, I would always try and make my way through a cuff of normal tissue.
So the lesson I would've learned on this image here is that I would've brought the needle in from have an angle to this lesion rather than straight down to a, to avoid biopsys on the surface of the liver, using a cuff of normal tissue to help you get a biopsy without having any bleeding complications.

Pancreatic Biopsies

Now onto pancreatic biopsies.
Well, as you know, we are in competition with endoscopic biopsies and also with a CT to do these types of biopsies.
And I must admit that I don't do as many pancreatic biopsies as I used to do in the past.
The reason is that endoscopy has taken over and there's a very safe and effective procedure in certain cases.
However, if you have liver lesions, it's probably wise the biopsy did the liver lesions first because you will prove that the mass in the liver, let's say on a CT scan, is in fact a metastatic pancreatic cancer to the liver.
And obviously in performing a liver biopsy, it's a lot safer than doing a pancreatic biopsy.
Also the other problem that you're having biopsying a pancreatic mass is that you often will have associated inflammatory changes with the cancer, which can prevent the accurate diagnosis of cancer among all these inflammatory changes.
And as I said, already, there is an increased rate of complications from biopsying these pancreatic masses in comparison to the liver.

Well, if one has to biopsy the pancreas, for example, if an endoscopic biopsy has failed and you don't have liver metastasis, then I would obviously biopsy the head and body with the patient in the supine position it, the masses in the tail.
I would use the right decubitus position going through and inter or using an intercostal approach.
In the supine position, sometimes it can be hard to see the pancreas because of the presence of gas within the stomach.
So in that instance, I will actually have the patient drink some sterile saline and distend the stomach and then use the water in the stomach as kind of a ultrasound window to the pancreatic mass.
Again, making sure that you switch your color doper on to watch out for vessels.
'cause these pancreatic masses often have small vessels on their surface and you wish to avoid that and not have the patient bleed.

This is just an example of a pancreatic biopsy using a CT guidance.
Now we generally would only biopsy lesions that we deemed to be unresectable because if they're deemed to be resectable, then they should be surgically excised.
Here's an example of biopsy of a large mass in the pancreatic tail, you will identify that I'm actually using the ultrasound to identify the stomach wall, which is over here, and the omentum, which is here.
I would switch my color doppler on, make sure there are no vessels in the omentum, and I will go through the omentum into the masses you see here proving that this is a pancreatic cancer involving the tail.

In terms of the accuracy of ultrasound or CT in providing a diagnosis of a pancreatic mass, it's pretty good actually.
We make a diagnosis up to 95% of the time.
Again, the complication rate is quite high at 2.6%.
The rate is not as high in the liver, nor as is it even as high with in the kidney.

Splenic Biopsies

Splenic biopsies usually have to be performed in the right decubitus position using a left intercostal approach or subcostal approach.
If the spleen is big, we're generally going after a splenic mass, and the suspicion obviously would be, it could be a metastatic lesion or a lymphoma.
Again, in counter distinction to the theory that you should not biopsy a vascular mass on a liver surface, you can biopsy a splenic mass on the surface of the spleen.
And I would reference the article below to make this point.

In this instance here, we have a mass within the spleen, as you can see on the CT scan on the left.
And then with the patient in the decubitus position going through the intercostal space, we can easily perform a biopsy of this lesion, again, using a coaxial needle for obtaining FNAs and cores.
Meloma obviously is a lesion that can go to the spleen.
And this instance, I biopsied this lesion again with the patient in the right decubitus position.
But unfortunately following the surgery, the patient hemorrhaged and needed a transfusion.

Renal Biopsies

Coming on now to renal biopsies.
Again, we're doing it either for parenchymal disease and somebody with renal failure, or we would be looking at a mass in the kidney to be biopsied.
Usually we have the patient in the prone position with a pillow underneath the abdomen to kind of stop the kidney from moving back and forth with bleeding, and also to make it more proximate to the posterior abdominal wall.
Again, we like to use a subcostal approach.
In some very obese patients where the kidney is very deep, it may not be possible to do the biopsy with the patient in the prone position, in which case I will actually put the patient in the decubitus position and then scan the upside and try and identify the kidney.
Because when you do this, what actually happens is the kidney will actually move downwards and forward and actually will be closer to the skin.
In patients like this who are very obese, if that technique does not work, one may have to go through the intercostal approach, but that really I don't like to do.
The other reason is if you use the intercostal approach, you often end up in the mid portion of the kidney, which always raises the possibility of the needle entering into the renal sinus in increasing the risk of bleeding.

So anyway, when we were doing a biopsy for parenchymal disease, again, I will use my coaxial needle technique.
I will bring the coaxial needle down to the capsule of the lower pole of the kidney, and I will obtain upwards of four cores.
Obviously, again, I will have the patient suspend the respiration fir and withdraw the needle because obviously you don't want to be move firing the needle off into a moving kidney.

This is just an example of the scan plane that we would use to get down to the kidney, and this is an example of where we would fire the needle off into the kidney right through the lower pole cortex.
As I said already, you don't want to go up too high because you don't want to have the needle end up into the renal sinus where all the blood vessels are, which is obviously increase your risk of having bleeding in the patient like this.
But bleeding does happen.
Usually the hemorrhage from the kidney is usually self-limited, does not require treatment on occasion.
However, you may have to do embolization if the bleeding does not stop in a timely manner.

So in terms of doing a biopsy of a renal mass, well usually you are trying to distinguish first of all, if the patient, let's say, has a lung cancer and then you discover a mass in the kidney, the question always would be, well, is this mass in the kidney a metastasis or does it represent a second primary such as the renal cell carcinoma?
Also, we biopsy renal masses when we have a mass in the kidney and the metastatic disease where the patient would not be a candidate for a surgical removal of the real mass.
Also, we do biopsies of these small solid lesions that prior to ablation or focal resection, and there's also debate out there whether we should do bosniac two F or the three biopsies.
But that's a discussion for another day.
Again, just like for the liver, when we have a mass, we take our coaxial needle, we insert it down to the mass, we insert the cutting needle through the coaxial needle and then fired off after suspending the respiration.

This is just an example of a large renal lesion, quite easily seen with the patient into decubitus position.
And you can see the lesion over here where we, this is our plane of the entry into the lesion and we can do easily do a biopsy.
Here's another example of another lower pole mass here.
Because of the size of the mass you do, you'd want to go towards this periphery if you could, as we did in this case here.
All another technical point here.
As we look at this CT scan, we can see that this lesion is in the front portion of the kidney.
It's got small bowel draped over it, and you can see that if we were to try and go from the back of this patient, we would end up going to the renal sinus and also through the pelvic eLocal system, which we'd want to avoid.
So when we're using our CT scan in terms of planning our approach, we would now see that putting the patient in the right decubitus position and using ultrasound to approach him from the side would be the way to go because in this instance, you would avoid entering into the renal sinus of this patient's kidney.

Adrenal Biopsies

Now, adrenal biopsies nowadays are not very commonly needed because they really can be characterized as either being a adenoma by CT or MRI or by being metastatic disease if they're a CT pet.
Occasionally, however, we do end up with a case where we can't determine whether the mass in the adrenal is a metastatic lesion or not, or where it could in fact represent adrenal cortical cancer.
Obviously, we do not wish to biopsy adrenal masses that are pheochromocytomas and so patients should be worked up appropriately to exclude that diagnosis if that is a consideration.
And adrenal biopsies, again, the same technique.

Now obviously most of these lesions are small and cannot be seen by ultrasound, but if they are sonographic visible, it's quite easy to do a biopsy usually with the patient in a lateral decubitus position.
And here we often would have to go through the intercostal approach because of its position high above the kidney.
Obviously you could use a subcostal approach if it would allow that, and basically you'd have to angle up to avoid the lung and the liver if it's on the right side.

Retroperitoneal Biopsies

In terms of retroperitoneal biopsies, again, you can have the patient in the prone position.
Supine art decubitus, again, we're usually going after lymph nodes, either trying to decide whether they're mets or lymphoma or in terms of them being a primary retroperitoneal malignancy.
One would like to obviously keep out of the way of the ureter to avoid the producing a oma.

Here's an example of a very large retroperitoneal mass, which I felt would be easy to perform by doing ultrasound guidance.
So using my CT scan as a roadmap, I inserted the needle down into the lesion here and I felt I had done a good job until the patient developed abdominal pain following the procedure and upon doing a CT scan because of continued pain, I found out that I had actually lacerated his pancreas and given him a extra pancreatic fluid collection, which actually required percutaneous drainage for a number of weeks.
So that obviously wasn't a very good decision to make.
I probably should have decided to actually do this biopsy using a CT guidance from the back, in which case I wouldn't have caused this problem.

Peritoneal and Mesenteric Biopsies

Now, in terms of peritoneal and mesentary biopsies, again, we would put the patient in the supine position.
Usually we're going after either omental implants or lymph nodes in the mesentary.
We're actually pretty good at making this diagnosis not as good as some things, but I think a diagnosis overall of 90% would be pretty good with a minor complication rate of only 3%.

As you can see in this instance here we have a CT scan on the left demonstrating extensive or mental caking in this patient with suspected carcinomatosis.
And then when you put your coaxial needle in, you can do a biopsy of the peritoneum like this.
Obviously one would try to avoid B bowel.
I would also like to make a commentary when you have a CES like this, you can accuracy, bleeding coming from the side of biopsy and that happens in every patient, but usually if their coagulation status is normal, you won't have any trouble.

Here's another example of a small implant, again, using your CT as a roadmap.
And this patient did have a history of lymphoma and so we were trying to prove that this was in fact a lymphoma to deposit.
You can see the image on the right here shows you that this is easily sonographic visible.
And then on the next slide, we inserted the needle into this an FNA into this mass and proved that it was in fact a lymphoma of the omentum.

Pelvic Biopsies

Pelvic biopsies.
Again, we're trying to make a diagnosis of tumor metastas or lymphoma.
We generally will go through the abdominal wall.
Actually, we can also put the patient prone and go through the SCIA notch if that's the best way to reach the mass.
And again, I will be using CT to make this diagnosis.
You can also do transrectal and transvaginal biopsies.

This is just an example of a patient with lymphoma who has got some external lymph nodes that are easily seen on CT scanning and we're biopsied using an ultrasound approach.
And again, I tend to like to use the coaxial needle we getting here, FNAs out of this lesion.
And also we followed through with core biopsies.

Now, in terms of doing transrectal transvaginal biopsies, if I'm doing a transrectal biopsy to get after a lymph node or a mass, I will generally give the patient antibiotics 24 hours before and on the day of the procedure.
In terms of doing transvaginal biopsies, you have to use probably conscious sedation 'cause these do hurt and so therefore I tend not to do those myself and I refer them to a colleague of mine who administers conscious sedation.

In this instance here, you can see we are using a transect approach to biopsy a lymph node in a patient who had a prior resection for a rectal carcinoma, thus proving that this was in fact a metastatic lesion in this patient.

Post-Biopsy Care

Now, in terms of the post biopsy care of these patients, we generally will keep patients for at least two hours of patient monitoring in our postsurgical unit.
After two hours, they're discharged home with instructions regarding the resumption of their medications.
Especially this will be true of their anticoagulants.
We also tell them to restrict activity for at least five to seven days, and we tell them that the small nick in the skin, which we cover with a bandaid, can be left alone until the bandaid usually falls off often within in the shower.

If however, the patient after discharge develops any dizziness or severe pain, they're instructed to call us.
And in fact, we do give them a phone number to call, which is a 24 7 number.
So as we can take care of these complications ourselves, if this should occur.

Complications

Now, minor complications include pain.
This is usually a self-limiting problem.
Usually it's gone within two hours.
It rarely needs pain medications.
In terms of vasovagal reaction, I think the fact that we tend to let our patients eat before doing our biopsies, we talk to them and reassure them throughout and that we give them a liberal amount of local anesthesia, has in fact reduced the incidences of vasovagal reactions.
And I rarely now have a vasovagal reaction, whereas in the past, I would have one also.
I would have one of these reactions maybe every couple of months or so.
Now it's a rare occurrence, so that's why I've gone to this way of doing biopsies anyway.
If they do develop a vasovagal reaction, I just lower the head, elevate the legs and weight and I will give them IV fluids if needed.
And I must say, I forgot to mention this earlier on, but we do have venous access in all of our biopsy patients.
Should this complication arise.

Now, major complications would be obviously doing a retroperitoneal biopsy would be a oma, which might require the placement of a catheter in the ureter.
Peritonitis is a very rare complication, and in fact, I had my first case just recently when I biopsy the patient who had mesothelioma.
But it really is extremely rare.
Obviously, it's unfortunate when it does occur and obviously one should try and avoid going through bowel, especially colon when doing these types of biopsies.
In terms of tumor seeding, I must say this is an extremely rare occurrence and thank goodness I've never had this happen in my career.

Summary

So in summary, ultrasound guided biopsies for me in the abdomen and pelvis are safe, they are accurate and they're cost affected.
My recommendations are you do not need to fast a patient and you can use a liberal amount of local anesthesia and use ultrasound to make sure you cover all of the abdominal walls.
When you put the needle in, it will not hurt the patient.
I also like using a coaxing needle approach as you put the needle in once and that's it.
You don't have to put it in many times.
Also, it allows you to put a 22 gauge or a core needle through that needle and to do as many biopsies as you like without having to continually reinsert the needle.
The other thing I would advise you to do is that over time you should look at your results in terms of your accuracy rate in getting a diagnosis in these patients because obviously if your numbers are not up to that report in the literature, then you need to look for ways to improve your future practice.

I've talked a lot about a lot of things here, so please see the reference list and the original article that I referenced for any more details.
Thank you very much.