Laparoscopy is an important tool in the veterinarians’ diagnostic and therapeutic armamentarium. It is a technique which is being used increasingly more frequently by veterinarians across the country.
This tape will demonstrate the basics of a laparoscopic liver biopsy in a dog. The first step is to make sure there are no obvious anesthetic or procedural risks in the patient. We will not discuss working up the patient for anesthesia at this point. However, we will discuss looking for coagulopathies. We will typically do a platelet count and a buccal mucosal bleeding time.
This is a template designed for people; it is a one time use device. It is a spring loaded device that makes a standardize cut in the buccal mucosa. There is a small slit in the bottom as seen here. The trigger is the pink tab and the blue tab here keeps the device from being inadvertently triggered. Once the blue tab is removed as such, it is then placed against the dog’s buccal mucosa as seen here and triggered by pushing the pink tab. A small cut is made and the dog begins to bleed. We now take absorbent paper and block the blood away from the edge without actually touching the cut surface. This is done until the bleeding stops. A typical mucosal bleeding time is less than five minutes and often less than four.
Next, we need to prepare the equipment. First, we will look at trocars and canulas. This is a metal trocar canula assembly. It has a smooth barrel. It is disassembled for sterilization. One of the first things you should do after removing the pieces is check the indicator to make sure that it was sterilized and here we see that it is. Here is the barrel of the canula and here is the valve, we will place the valve into the barrel and lock it in. There are many different type of canula assemblies, this is simply one. Next, we will take the gray rubber seal and put it at the top of the canula. This particular canula has a valve on the side. We will now put the trocar into the canula, it slides in easily. This is a completed assembly.
This is a different type of canula, this is a plastic canula with threads on the barrel, which allow it to be screwed into the body wall so that it does not move in and out as easily as the other. This particular type has a plastic inner valve. We will place the plastic valve into the barrel of the canula as seen here and then we will screw the top of the canula on to lock the valve in place. The disadvantage is that this valve can be damaged if you are not careful so after putting on the gray seal on top and getting ready to place the trocar to the canula, you must be a little bit careful. If you meet undo resistance that means that the tip of the trocar has caught the plastic and will tear it if you push any harder, you must withdraw it and put it in again.
Here we see a third type of trocar canula. This is a unit used in human medicine designed for one time use. Next, we will prepare the Veress needle. You will note that there are two green plastic devices on the ends of the two parts of the Veress needle; this is because we are using Sterrad sterilization and these are necessary to insure that the interior has been sterilized. We will take the inner blunt needle, which has a spring on it, insert it into the outer sharp needle and it screws together and this is now a spring loaded Veress needle. As you can see now, the inner needle can be pushed in and out spring loaded and if you look at the tip, you can see the blunt inner needle going in and out of the sharp outer needle.
Next, we will take a look at the biopsy instruments. There are two biopsy instruments here, a black one and a silver one. The black one is the one that we most commonly use for the liver biopsy. This is a double spoon device which we typically use for the liver because it takes a larger piece of tissue. The silver one is a punch biopsy device typically used for the pancreas. It can cut through harder tissue but takes a smaller sample. The double spoon device is preferred.
Next, we are assembling the camera, our particular camera, comes in two parts, the camera and the adapter. We are now screwing the adapter into the camera. There are many different types of cameras and yours maybe different than ours.
Next, we will get the light cable. And then finally we will get the insufflation tube which has a lower lock tip on both ends. This is anti-forward compound and is designed to prevent the tip of the endoscope from forwarding up when it is placed on the warm peritoneal cavity. We have solution and a little green sponge which has adhesive on the back. The sponge is what we will put the solution into in a minute, but right now we will simply put the sponge on the table where it will adhere. Here are the telescopes and a protective metal box. This is the complete surgical table. It has a minor surgery pack with various hemostats, Backus-style clamps, scissors, needle holders, etcetera. The drapes, the camera, the light cable, the tubing, the canulas and trocars and the Veress needle.
The dog is on the table. She is making sure that the bladder has been expressed prior to the procedure. The dog in this case is in dorsal recumbency. Typically, I have them in left lateral or partial left lateral recumbencies, so that the falciform ligament falls off to one side. This particular animal is one in which we want to look on both sides of the falciform carefully therefore, it is on dorsal recumbency. Positioning will depend upon specifically what you are looking for. I like to have the head elevated at least 15 degrees above the tail so that the intestines tends to fall away from the liver and gives me a little bit better view of the liver in that region.
We are doing a routine three scrub surgical preparation. In general, it is always best to prepare a larger area than you think you will need. Sometimes as you place the canulas, you find that it is advantageous to move more laterally or more medially and by having a generous preparation, you have that option.
Now, the excess soap is being removed with a sterile towel. We will now quarter drape the animal as we would for any laparotomy. Give yourself a generous area so that you can place the canulas any place that you deem necessary. The quarter drapes will be attached with Backus-style clamps.
Next, a sterile drape will be put over the animal. Here, you will note that there are two of us, but this is typically a one person procedure, having two makes it easier when you are first learning. A hole will be cut in the drape. The size of the sterile field bracketed by the quarter drapes. This ends will be tucked in and attached to the underlying quarter drapes with Alice tissue forceps.
Next, we palpate the abdomen to make sure there are no previously unsuspected masses or nodules or anything. There we have the costal arch, there is the midline. Typically, we will be placing our canulas and Veress needle back away from the costal arch. Before we actually make the incision, we want to palpate and make sure there is nothing below the site where we will place the Veress needle. A very small one millimeter incision is made through the skin only. As we begin to place the Veress needle, it is important to remember that the Veress needle is a spring loaded device and is designed so that the blunt inner needle retracts when it is pushed against something such as the body wall. Note how the needle is being held here. We are grasping the middle of the needle; we are not grasping the end. If you grasp the proximal end, which is to the left as you view the screen, you will prevent the blunt inner needle from retracting and exposing the cutting tip. Now, we will place the needle into the incision and now we will begin to apply pressure. As you push in, suddenly, there will be a pop as you feel yourself going through the abdominal wall. But it is important to know if you went to the abdominal wall only partway through. Here, as I bounce the needle back and forth, you see the whole wall move, which means that we did not get all the way through. So you push a little bit further, it will pop through again, and now it will move freely, meaning it has entered the peritoneal cavity. Now, to make sure that we have not perforated anything, next we aspirate to make sure we do not get air or blood and then we do the hanging drop technique. We will take a syringe filled with sterile saline. We will fill the needle with it and the as we withdraw the syringe from the needle, we will put a drop of saline at the tip. As the anesthesiologist bags the animal, it will change the intraabdominal pressure. And if the tip of the Veress needle is free in the peritoneal cavity, the water drop will be sucked down as you will see here. There we insert it and if we put a drop right there, you can see that it is sucked in just there. This means that we have entered the abdominal cavity and we do not have the needle and then a pouring from an organ.
Next, the tubing is attached to the insufflator. We attach this tubing to the drape by means of an Alice tissue forceps, as seen here, so that it cannot fall away and become contaminated or pull the Veress needle out of the abdomen. The tip will now be attached to the needle here and insufflation will begin. As we begin to insufflate carbon dioxide, you will find that the pressure gauge should read something between 8 and 15 mmHg. This is of normal pressure. If the pressure gauge reads more than 15 mmHg, it means that the tip of the Veress needle is against something and the flow the carbon dioxide into the abdomen is being impeded, the needle will have to be repositioned. We distend the abdomen until it is nicely distended but not greater than 15 mmHg. Good abdominal distention will mean that it is very unlikely that our trocar canula will perforate or penetrate any of the intraabdominal organs. We will now place the canula into the abdomen. Placement is important. A basic premise of endoscopy is that it is much easier to see thing from a distance than if you are too close. In general, you need to think about how much of the canula will be in the abdomen and realize that if you have the tip of the canula next to the liver, it will be very difficult to view it as you would like. Typically, we place the canula on a dog this size about midway between the costal arch and the colored part of our sterile field. We will first mark the site where we are going to place the canula. By twisting one canula against the skin, this will cause a circular depression. Now, we will cut through the skin from one edge to the other. We are cutting just through the skin, not into the deeper tissue.
Now we will discuss handling the trocar canula. Handling is very important. First, as seen here, I am holding the trocar canula with my index finger extending down the barrel of the canula. I am doing this, so that as I push the trocar canula through the abdominal wall, it is unlikely that the abdominal wall will suddenly give way and the trocar canula will rush into the abdominal cavity and puncture or lacerate an organ. The next thing to notice is that I am holding the trocar canula such that the end of the trocar is against the palm of my hand and the trocar is being held in the canula such that when I start to push, the trocar canula assembly into the abdominal wall, the trocar cannot back out. This is exactly the opposite of what we did with the Veress needle. When we handled the Veress needle, it was important for the inner blunt needle to be able to retract as I push the assembly through the abdominal wall. But with the trocar canula, I want the trocar to remain extended through the canula as we go through.
We will now place it against the abdominal wall and with a twisting motion, carefully push it through. There will usually be a bit of a pop as you go through the abdominal wall. Here we are removing the trocar leaving the canula in place. Now, we will connect the light cord and the camera cord to the drape so that once again so that they will not fall and contaminate anything. We are turning the light on now although usually I would wait so that there is no chance of anyone looking into it and being blinded. The light is quite bright.
Again, we will be using Alice tissue forceps to secure these two cables to the drape. Now we will attach the light cable to the telescope and now we will attach the camera to the telescope. This is the fog out solution, we will squirt the solution into the green sponge and put the tip of the telescope there. Now we will take white gauze and we will wipe balance. This is important so that we see true colors. Remember, one of the advantages of laparoscopy is that you can see more than you can with ultrasound and sometimes discoloration is quite important. After we have white balanced it, we will insert the telescope through the canula, now notice how I am going to hold the canula with one hand and the telescope with another. And from the instant that the telescope enters the canula, all we do is look at the monitor. Here we are sliding down. You will note that if at first it is dark, we are go have to turn the light up a little bit and you are seeing some omentum lifted up by the Veress needle. We will now put that back down. Now, we are going to take a cursory look through the abdominal cavity to make sure that there is nothing there to surprise us especially as we put the next canula in. The abdominal cavity that you are seeing here is not the one of the animal that you saw, rather this animal is in a modified left lateral recumbency. You can see the liver here, the pink pancreas with intestines and stomach. We are looking at the hyalines of the liver, you can see the heart beating through the diaphragm and the gallbladder off to the right side. The falciform fat is falling off to the side as you can see here. You can see intestines. If we look down, we can find the spleen. As we keep looking totally, we will find that this particular animal has had surgery in the past. We can see adhesions to the abdominal wall. We are now looking at the urinary bladder and off to the right, on the abdominal wall, you can see white scaring. Then we can come back and see intestines with omentum and mesentery. Finally, as we head back towards the left, which is actually the animal’s right side, we will begin to see the kidney and the retroperitoneal fat here. After you have examined the abdominal cavity, it is time to place the second canula. The second canula is placed very much as the first one is with the exception that we will watch the canula enter the abdomen so as to insure that we do not penetrate any structures such as the spleen. First, we will show you the placement of the canula from the outside as we did before. In this case, we are going to use some hemostats to enlarge the skin opening, once again this is just the skin, we are not opening the deeper tissues.
Again we are going to hold the canula so that the trocar cannot be pushed out as we push the assembly through the abdominal cavity. Note that my index finger is along the shaft because this is a threaded canula, once it is in, I will have to screw it through the abdominal wall. Now, let us take a look at this and see what it looks like from the inside. Here we are spreading the skin with the hemostats. You want to maintain visualization, and you would prefer not to poke the end of the telescope with the pointed trocar. By observing it from the inside, we can make sure we do not perforate or lacerate anything especially the spleen. Although it is very seldom that a splenic laceration is a major concern. That primary disadvantage is that there is a lot of bleeding which makes visualization difficult. Once you have the second canula in place, it is usually a good idea to put the telescope through that canula, so that you can look around and see if you can see anything from that side that you could not see from the first side. After having looked through both canulas, it comes time to explore the abdomen.
We will now use the biopsy forceps to help us explore the abdomen. You could use a blunt exploring probe instead, but if you use the biopsy instrument and keep it close, that is an acceptable alternative. You could also use babcock forceps and other instruments. Notice how I hold the telescope in one hand and the biopsy instrument in the other. Note especially that I found the end of the trocar and I watched my instrument come into the abdominal cavity. This is very important. You will always find the trocar and watch the biopsy instrument coming in. Always find the biopsy instrument with the telescope. Do not leave the telescope stable and try to put the biopsy instrument in front of it unless you lacerate organs or perforate organs.
We will now use the close biopsy instrument to lift the different liver lobes and look around. This particular animal has a somewhat small liver and very little body fat, which makes for easy examination. You can use the tip of the instrument of probe to palpate. Remember that you always want to keep your biopsy instrument in view. Here we are looking under the liver lobe that has been lifted by the biopsy instrument. We examine the hyalines region of the liver. Here we are going to pull back the pancreas. And you can actually see one of the great vessels of the abdomen, there. At this point, you wish to do a slow methodical examination, remembering to always keep the tip of the biopsy instrument of the probe in view. This is best done as a one person operation with one person handling both the camera and telescope and the instrument probe or the biopsy instrument.
After you have examined the abdominal cavities sufficiently, taking biopsies is the next step. Here, we will watch the biopsy instrument approaches the liver and if you lose the instrument, go back and find it in your field of vision. Again, always find the biopsy instrument with your telescope, not the reverse. It is easy to take biopsies from the edge. Note that you will never biopsy unless you can see exactly what you are grasping. Here, we will open the jaws, push into an edge, bite, maintain pressure and then pull off a piece of tissue. In this case, there is very minimal bleeding. The biopsy instrument is removed from the animal and the liver biopsy is placed upon a non-absorbent surface. Do not place it upon gauze since this will cause artifact. Once you have the biopsy, again, you will the telescope to find the opening of the trocar first and then place the biopsy instrument through it. Now, we will biopsy another liver lobe. Please note that in this case that we have to position the biopsy instrument to get a good bite of this lobe. Also note once again that we only biopsy what we can see. You never close the biopsy forceps unless you can see exactly what you are grasping. In this case, there is going to be a little bit more bleeding than before, but quite acceptable. Bleeding is magnified by the telescope and appears to be more than it is really present. This is a fairly routine amount of bleeding of no clinical consequence. Again, we will find the trocar, follow the biopsy instrument through it and now, we will biopsy a third liver lobe.
We will typically take six to eight liver biopsies from three or more lievr lobes. Please note the size of these biopsies. At this point you may decide to cut some in half and some for culture. You may decide to save from frozen for elemental analysis later. But in general, we would like to have a fair minimum of four and preferably, six pieces of tissue in formalin for histologic examination.
We are now finished, so we will disassemble the equipment. The telescope is the most delicate piece of equipment and you will want to put it on the table, unattached to anything, so you do not have worry about it being knocked off or dragged off the table. The Veress needle is removed. We will now open the valve on the canula and allow the carbon dioxide to escape from the abdomen. We would like to get as much of the carbon dioxide out as possible. Notice how the abdomen is now no longer distended. We will do a two-layer closure with one suture through the abdominal wall puncture and one to the skin. If you have an animal that has satieties, it is very important that you get a very tight closure or there will be much leakage and a very large seroma, which will be displeasing to the owner. If you are having trouble doing this closure, you might want to extend the skin excision 2 mm near the direction to insure that you can get a good bite and a good closure of the abdominal wall. These sutures are cut short. It works best to do this one canula at a time. If you remove both canulas initially, the skin and body wall may shift, such that you have a difficult time finding the incision through the body wall.
We will generally place one interrupted or one crocheted suture through each skin incision. We generally do not put a suture to the side of the Veress needle. Remember not to tighten the sutures down too much or you will have more difficulty removing them later.
Once the procedure is over, the animal has recovered; post operative monitoring consists of checking the mucous membrane color, capillary refill time and pulse every 15 minutes for the first hour, every 20 minutes for the second hour, and every 30 minutes for the third hour. After that time, if the animal has fully recovered, they can be sent home. This procedure is designed to have this patients go home the same day. Analgesics can be used, in some cases, they are not necessary, but certainly, they can be used. Here we see the patient after the procedure. It has two sutures in the abdomen. Most clients are very pleased by the minimally invasive nature of this procedure. This animal is typically evidence of minimal to no pain after the procedure and the biopsy samples that are obtained are usually far superior to what we obtained with ultrasound guidance.
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