Laparoscopy

C H A P T E R  28  Laparoscopy

INSTRUMENTATION Keith Richter The use of laparoscopy for diagnostic and therapeutic purposes has increased dramatically during the last 20 years. Increased use and acceptance of laparoscopy stems from technical advances in equipment and instrumentation, improved access and training, client expectation, and excellent results with these minimally invasive procedures. Advanced therapeutic procedures will be performed more commonly as veterinarians adopt these techniques. Compared with open abdominal surgery, laparoscopy has several distinct advantages, including less postoperative pain, lower infection rates, improved visualization in many cases, lower cost, and shorter hospitalization times. Laparoscopy also has some advantages over other minimally invasive procedures, such as ultrasound and ultrasoundguided biopsy, including sample quality and direct visualization.

Equipment Light is transmitted from a remote light source via a fiberoptic light cable to the rigid fiberoptic laparoscope (telescope). Light transmitted through the light cable passes through incoherent bundles (randomly aligned), whereas light passing through the telescope passes through coherent bundles (spatially oriented). This creates a proper image when the lens system focuses the light at the eyepiece. The fibers in the telescope are delicate, and care must be taken to avoid bending or crimping the shaft. Modern telescopes are constructed so they can be sterilized with a conventional steam autoclave. For purposes of illumination, a light source of 150 to 300 watts is required to adequately illuminate the abdomen, particularly in largeand giant-breed dogs. Size and viewing angles of laparoscopes vary, some of which are depicted in Figure 28-1. Small-diameter scopes (2.7 to 5.0 mm) have a smaller image with a narrower field of view. Light sources with greater intensity and video cameras with greater light sensitivity are needed with smaller scopes. Scopes up to 10-mm diameter can be used, and although these generate a bigger and brighter image than 5-mm–diameter scopes, this advantage applies only to very large dogs. Scopes are also available in various degrees of angulation of view, from 0° (direct forward viewing) to 70° angle viewing. The 0° angle view has the field of view centered on the long axis of the scope, and thus is easier to use and generally preferred for most procedures. A 30° angle scope can be used to view structures to the side of the tip, and through rotation can be used to expand the field of view. Angled scopes are more difficult for inexperienced operators

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with regard to spatial orientation, and they pose greater difficulty when using instruments through a second or accessory puncture site. The technique of triangulation to find the tip of the instrument is particularly more difficult with an angled field of view. Taking all these factors into account, a forward-viewing (0°), 5-mm outer diameter, 35-cm long scope is preferred for most dogs and cats. As most laparoscopic instruments are 5 mm in diameter, this provides more versatility by allowing the scope and instruments to be interchangeable with the same cannula. The operator must ensure the scope fits properly through the selected cannula, that the light cable has the appropriate connection to the telescope, and that the video camera fits properly onto the eyepiece. Most scopes have no biopsy channel. Operating scopes have a 5- to 6-mm channel, with an eyepiece extending from the proximal end (see Fig. 28-1C). These scopes allow introduction of instruments through the same puncture site as the scope. This has the advantages of reducing the number of puncture sites and facilitating identification of the instrument tip for inexperienced operators. The major disadvantage of operating scopes is the limited ability to manipulate instruments passing through the channel. An accessory or secondary puncture technique is usually preferred by more experienced laparoscopists (see “Accessory Puncture Sites” section). Video capabilities can be achieved with a charge-coupled device (CCD) video camera mounted onto the eyepiece of the telescope. These video cameras have a high resolution, an image magnification by 5 to 15×, and a high image quality. Cameras are constructed with a lens, prism assembly, and one or three chips that convert light to an electronic signal. Cameras with three chips (each representing the primary colors of red, green, or blue) generally produce better images than cameras with just one chip. More recently, highdefinition (HD) cameras have become available and produce a superior image quality. Video technology is now essential for interventional or operative laparoscopy. To visualize abdominal structures, a pneumoperitoneum must be created to lift the abdominal wall away from the viscera. This is accomplished by insufflating gas through tubing attached to a Veress needle (Fig. 28-2). The Veress needle has a spring-loaded blunt inner portion and an outer cannula with a sharp point. The sharp point is used to penetrate the abdominal wall. The inner blunt portion is then protruded past the sharp point and is maintained in that position to avoid traumatizing abdominal organs. Gas can be continually insufflated as needed throughout the procedure. Carbon dioxide gas (CO2) is recommended because it has the advantage of being rapidly absorbed, thereby minimizing the risk of air embolism. Air embolism is a complication that is more likely to take place if using room air. The disadvantage of CO2 is that it is slightly more irritating to the peritoneal surface and therefore requires a slightly

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A

B

C Figure 28-1  Various rigid telescopes. A, A 5-mm scope with a 0° angle tip. B, A 10-mm scope with a 30° angle tip (insert: close-up of tip). C, An 11-mm operating scope (insert: close-up of tip with 5.5-mm channel).

A Figure 28-2  A, Veress needle. B, Close-up of tip with sharp point in position to penetrate the abdominal wall. C, Close-up of tip with blunt inner obturator protruded in position to avoid trauma to abdominal organs.

greater depth of anesthesia. The pneumoperitoneum is maintained throughout the procedure with an automatic insufflator, which continuously administers gas to maintain pressure. Insufflators regulate both flow rate and intraabdominal pressure. Initial gas insufflation should be at a low flow rate (e.g., 1 L/min) to permit accommodation to the increasing intraabdominal pressure. If the pressure suddenly rises during insufflation, it is often a result of omental or mesenteric obstruction, or the incorrect placement of the needle. The position of the needle should be adjusted by gently moving it in and out of the abdomen; occasionally it must be replaced completely. Once optimal insufflation has been achieved, a higher flow rate can be used to maintain desired pressures. Ideally, intraabdominal pressure should not exceed 10 mm Hg (cats and small dogs) to 15 mm Hg (large dogs). Excessive pressure decreases central venous return and reduces diaphragm movement, causing decreased ability to ventilate. These effects are unlikely to occur at recommended abdominal pressures, but should be considered in patients with preexisting cardiopulmonary disease.

B Figure 28-3  A, Trocar/cannula assembly with threaded shaft. B, Telescope inserted through cannula with smooth shaft.

After the creation of the pneumoperitoneum, the laparoscope is introduced into the abdomen with the use of a trocar/cannula assembly (Fig. 28-3). The cannula is a metal or hard plastic sleeve with a one-way valve that permits passage of instruments (such as the trocar, laparoscope, and accessory instruments) and prevents the escape of gas. The trocar is a sharp-pointed stylet that is used to penetrate the abdominal wall. Once the trocar/cannula assembly penetrates the body wall, the trocar is then removed, leaving the cannula in place for introduction of the laparoscope.

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SECTION III  Diagnostic Approach to Gastrointestinal, Pancreatic, and Hepatobiliary Problems

Trocar/cannula assemblies come in a variety of sizes and styles. Trocars with a pyramidal tip have a cutting edge that penetrates the abdominal wall more readily than trocars with noncutting conical tips, although they are also potentially more traumatic. Some trocars have a retractable blade within the tip. A well-established pneumoperitoneum must be present for this style to be used to avoid the risk of intraabdominal organ trauma. Cannulae are used to allow passage of instruments in and out of the abdominal cavity while maintaining the pneumoperitoneum. They are constructed with a one-way valve to permit introduction of instruments without the escape of abdominal gas. Additionally, there is a rubber seal at the proximal tip to prevent escape of gas when an instrument is in place. Some cannulae have a side port to allow attachment of insufflation lines to introduce gas during the procedure. The shaft of the cannula can be smooth or threaded. A threaded cannula is more stable and unlikely to move within the abdominal wall during the procedure. Sometimes it is desirable for the cannula to move in and out of the abdominal cavity, such as when the cannula is inserted deep into the abdominal cavity for tissue biopsy. In these instances, a smooth nonthreaded shaft is preferred. For imaging purposes, an appropriately sized cannula must be used to ensure adaptation to the telescope and other instrumentation.

Accessory Puncture Sites Accessory puncture sites are made for introduction of additional trocar/cannula assemblies. Accessory puncture sites permit the introduction of a variety of palpation, biopsy, and surgical instruments. These instruments are elongated, narrower versions of standard surgical instruments. A “basic” laparoscopic accessory pack should consist of a blunt metal probe, “spoon” or “clamshell” style (oval cup) biopsy forceps, grasping forceps, scissors, suction device, cautery instrument, and Babcock forceps (Fig. 28-4). An “advanced” laparoscopic accessory pack should also include retractors, reticulating instruments (which allow the tips to bend or be deflected), clip applicators, suturing devices, advanced hemostasis devices such as the Harmonic scalpel (Ethicon) and the LigaSure device (Covidien), and stapling equipment. The use of stapling equipment

Figure 28-4  Laparoscopic instruments. From top to bottom: blunt metal probe, “spoon” or “clamshell” style (oval cup) biopsy forceps, grasping forceps, scissors, suction device, cautery instrument, and Babcock forceps.

permits additional procedures such as vessel ligation and bowel resection.

Indications and Contraindications for Laparoscopy Common indications for laparoscopy are for the evaluation of hepatobiliary disease. Laparoscopy allows procurement of large specimens (similar in size to surgical biopsies) using a 5-mm “spoon” or “clamshell” forceps (see Fig. 28-4). Samples obtained with these instruments have a superior diagnostic yield compared with needle biopsies, which have a reported 50% concordance with histologic findings from surgical biopsies.1 Furthermore, the ability to visualize the liver gives the clinician a better feel for the pathologic process present and its distribution. Laparoscopy can also be used to examine and biopsy the right limb of the pancreas, an organ that can be difficult to image with abdominal radiographs and ultrasound. Other organs that can be biopsied via laparoscopy include the kidney, spleen, prostate, intestine, mesentery, omentum, and parietal peritoneum. Laparoscopy can be used to diagnose and stage abdominal tumors through direct visual assessment and biopsy. Laparoscopy can detect lesions less than 1 mm in diameter on the surface of organs. It can guide the aspiration of gallbladder, loculated ascites, and abdominal cysts or abscesses. Laparoscopy can guide transabdominal intrauterine artificial insemination. Laparoscopy can also be used for the evaluation of abdominal trauma. Injuries such as hepatic or splenic laceration, diaphragmatic hernia, bladder rupture, renal rupture, and abdominal hernia can be readily identified. There are also a variety of surgical or interventional procedures that can be accomplished laparoscopically. Contraindications for laparoscopy include general anesthesia in an unstable patient, coagulopathy, diaphragmatic hernia, abdominal adhesions, and insufficient clinical experience. It must be emphasized that these are all relative contraindications, and the risks of a laparoscopic procedure must be weighed against the benefits of the procedure to the patient.

General Laparoscopic Technique Several skills are required to perform a successful laparoscopic procedure.2 The operator must have a good grasp of abdominal anatomy, surgical principles, anesthetic induction and maintenance, and operative use of laparoscopic equipment. Compared with surgery, laparoscopy poses three additional challenges—two-dimensional imaging, lack of tactile sensation, and problems with depth perception—all of which pose significant challenges for the inexperienced laparoscopist. The operator must be familiar with the general feel of the instruments, and how slight movements of the camera head can result in wide excursions of the image. Tactile sensation can be developed with practice through the use of a blunt probe. Fluctuant structures can usually be distinguished from solid structures using the blunt probe. There is also a fulcrum sensation that occurs with instrument movement. Because the instruments and scope are entering the abdominal cavity through a cannula, movement of the tip is in a direction opposite to that of the handle. Thus, when the hand and handle are moved upward, the tip of the instrument moves downward. When the hand and handle are moved to the left, the tip of the instrument moves to the right. Another necessary skill necessary is triangulation, because the angle of the scope and the angle of the instrument form a triangle. Triangulation permits the operator to find an instrument placed through a secondary or accessory cannula in the field of the scope. The angle of entry of each component of the triangle must be recognized to

avoid frustration when attempting to find the instrument tip. One technique that is helpful is to move the scope further away from the anticipated point of the instrument tip. This will increase the field of view. Once the tip of the instrument is located, the scope can be moved closer to the instrument to improve visualization. At this point the instrument and scope are moved in parallel so that the instrument tip never leaves the field of view. This technique will reduce unnecessary anesthesia time. The skill of triangulation becomes more challenging when using an angled scope (such as a 30° telescope). If the viewing angle is directed upward and an instrument is inserted from the side, it appears to come from below and to the side of the field of view. Laparoscopy is best performed under general anesthesia. The position of the dog or cat and the location of the various puncture sites depend on the procedure, patient’s size, and organ of interest. Because the port placement is so critical to a successful procedure, placement of the ports must be carefully planned and the site marked on the patient ahead of time to ensure a sterile field. In general, ports should not be placed too close together to avoid crowding of instruments with each other or with the scope. Furthermore, triangulation to locate instruments and subsequent manipulation of instruments is more difficult when they are placed too close to the scope. If it is determined that port placement is not acceptable, it is often better to place an additional port to allow completion of the procedure than to struggle through the procedure with suboptimal port location. Prior to starting the procedure, the urinary bladder should be emptied. A right lateral or right lateral oblique approach is generally preferred for the liver, gallbladder, biliary tract, pancreas, right kidney, and right adrenal gland. The main advantage of this approach is that it avoids the falciform ligament, which is commonly encountered with a midline approach. The main disadvantage of a right-sided approach is the inability to see most left-sided abdominal structures. A midline approach is occasionally used for more complete evaluation of the liver (more of the liver can be seen by this approach than by a right-sided approach) and many interventional surgical procedures. Although the falciform ligament may impede the procedure, it can be avoided by placing the central port just lateral to midline and caudal to the umbilicus. In a lateral approach, the scope is placed several centimeters lateral to midline, depending on the size of the patient. A left-sided approach is seldom used, but is necessary to visualize the left kidney and left adrenal gland.

Complications of Laparoscopy Potential complications of laparoscopy include those related to general anesthesia, inadvertent organ damage during instrument introduction, excessive bleeding during biopsy or other intervention, other surgical complications, overdistention of the abdomen, air embolism, subcutaneous instillation of gas, tension pneumothorax if the diaphragm is inadvertently punctured, and postoperative infection. Operator experience, good patient planning, and meticulous attention to procedural detail minimizes the probability of these complications. Postoperative pain should be anticipated and should be addressed with appropriate analgesics.

Laparoscopic Surgery Many laparoscopic surgical procedures are currently being performed on dogs and cats. These include ovariectomy and hysterectomy, adrenalectomy, bile duct exploration, gastropexy, cystotomy with

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calculus removal, cryptorchid testicle removal, jejunostomy tube placement, splenoportography, cholecystectomy, and others. Limitations of laparoscopic surgery include the two-dimensional image, restricted freedom of movement of the instruments, restricted sense of touch, limited opportunity to move the position of instruments once cannulae have been placed, the need for extensive training, and limitations on instrumentation available for laparoscopy. As clinicians and equipment manufacturers address technical limitations, many surgical procedures should become more amenable to laparoscopic surgery.

Newer Laparoscopic Techniques One recently developed innovative laparoscopic technique described in human beings is natural orifice transluminal endoscopic surgery (NOTES). This technique involves insertion of an endoscope into a natural orifice (such as the stomach, vagina, or colon), access to which is then used to perforate the wall to gain entrance to the peritoneal cavity. Many interventional procedures can be performed using this technique. The approach is thought to limit postoperative pain, decrease wound problems, and offer improved cosmesis. Transvaginal cholecystectomy is the main procedure being performed to develop the NOTES technique, although other surgical procedures can also be performed with this approach. There are many challenges to overcome to accomplish these procedures successfully. Luminal access can be achieved with new steerable trocar/cannulae. Flexible scopes have been developed with multiple steerable channels to allow introduction and manipulation of a variety of instruments to be used for the surgical procedure. Tissue or organ retraction is also very challenging. This has been overcome by use of special intraluminal retraction devices (Endograb, Ethicon), articulated graspers, and deployable devices (T-tag suture devices). Closure devices also have been developed, including endoscopically deployed clips. These include the Resolution Clip (Boston Scientific) and the QuickClip2 (Olympus). Another method of overcoming these technical challenges is to combine a single puncture transabdominal laparoscopic port with transluminal access (called hybrid NOTES). This improves retraction and allows more versatile instrumentation. The single-incision laparoscopic surgery (SILS) is another newly introduced technique. This technique permits the introduction of multiple instruments through one large port into the abdominal cavity. Several manufacturers have developed these devices. Furthermore, gently curved rigid instruments have been developed for this technique. The gentle curve permits better triangulation of instruments despite their insertion into a common port. In addition, reticulated instruments with steerable tips make this technique more versatile. Intraoperative ultrasound (IOUS) during laparoscopic cholecystectomy is becoming increasingly commonplace in human laparoscopic surgery. High-resolution ultrasound probes are integrated into the tip of laparoscopically deployed instruments. The use of IOUS can help define biliary anatomy, including the entire common bile duct. Abnormalities, such as common bile duct calculi, sludge, or aberrant biliary anatomy, can be identified. The procedure only adds 5 to 7 minutes to a cholecystectomy, and can potentially change the management of the patient. Only time will tell whether NOTES, SILS, or IOUS will be routinely applied in dogs and cats. Controlled clinical trials will be necessary to define the role of all laparoscopic procedures in veterinary medicine.

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SECTION III  Diagnostic Approach to Gastrointestinal, Pancreatic, and Hepatobiliary Problems

LIVER AND BILIARY TRACT Eric Monnet and David C. Twedt Laparoscopy is a simple procedure associated with few complications. Despite the advent of newer laboratory tests, imaging techniques, and ultrasound-directed fine-needle biopsy, laparoscopy remains a valuable tool when appropriately applied in the diagnostic plan in patients with suspected hepatobiliary disease. Laparoscopy can be used to safely evaluate the liver and the biliary system. Laparoscopy can replace laparotomy for the visual inspection of the liver and biliary system, and to obtain biopsies. Laparoscopy may reveal small (0.5 cm or less) metastatic lesions, peritoneal metastases, or other organ involvement that is not easily identified by other imaging techniques.

Preparation, Restraint, and Surgical Considerations With few exceptions, laparoscopy is performed under general anesthesia. However, because liver biopsy is a procedure of relatively short duration, it can be accomplished in some patients under light sedation and local anesthesia at the cannulation sites. If the pneumoperitoneum with CO2 insufflation interferes too much with the excursion of the diaphragm and ventilation of the patient, general anesthesia with intubation and positive ventilation will be required. The right lateral approach is recommended for diagnostic evaluation of the liver and extrahepatic biliary system. With this approach the right limb of the pancreas can also be identified, evaluated, and biopsied. During the right lateral approach, the patient is in left lateral recumbency and the portals are placed in the caudal part of the abdominal cavity from the right side. Two portals are sufficient to perform a liver biopsy. A ventral approach can also be used to visualize the liver, gallbladder, and biliary tract. In the ventral approach, the primary portal is placed on the midline caudal to the umbilicus. The secondary portal is introduced in either the right or left side of the abdominal cavity. With the ventral approach the left lobes of the liver can be more readily visualized although the falciform ligament may hinder visualization of the anterior abdomen, especially in obese animals during a ventral approach. Ascites, prolonged bleeding time, and poor patient condition are the only relative contraindications to laparoscopy. If ascitic fluid accumulation is mild, it can be removed prior to or during the laparoscopic procedure. Closed suction drainage can be placed in the abdominal cavity at the end of the procedure to prevent continued leakage through the portal sites. Coagulation parameters (prothrombin time, partial thromboplastin time, buccal mucosal bleeding time) should be evaluated prior to laparoscopy and liver biopsy. Although coagulopathy is a relative contraindication to liver biopsy, coagulation status does not necessarily predict whether the patient will bleed from laparoscopy or liver biopsy. Laparoscopy does permit the operator to visually select biopsy areas that are less vascular and to monitor the extent of bleeding following a biopsy.1

Evaluation of the Liver and Liver Biopsy Eighty-five percent of the liver surface can be visualized during routine laparoscopy As with exploratory laparotomy, the liver is evaluated for size, color, shape, and sharpness of edges. For the diaphragmatic surface of the liver, an angle endoscope can be used to image the more cranial aspects of the liver. A palpation probe is

Figure 28-5  Acquired portosystemic shunts in a dog with end-stage liver disease.

used to manipulate the different lobes and to visualize the visceral surface of the liver and extrahepatic bile ducts. Grasping forceps should not be used to manipulate liver lobes because the liver parenchyma is often too friable and at risk for traumatic injury and bleeding. With the right lateral approach, the portal vein can be evaluated for size and turbulent flow. Acquired shunts can be observed across the omentum and around the left kidney if portal hypertension is present (Fig. 28-5). Portal pressure can be measured directly after exteriorization of a loop of jejunum and catheterization of a jejunal vein. Manometry is used to measure portal pressure, and a portovenogram can be performed to further evaluate the portal vasculature. After completion of the portovenogram and measurement of portal pressures, the catheter is removed and the loop of bowel is returned into the abdominal cavity. Laparoscopic liver biopsy is considered by many to be the preferred method of obtaining liver tissue for routine histopathology.1 A 5-mm cup biopsy forceps provides sufficient liver tissue for routine analysis and is superior in quality to 18-gauge (G) needle biopsy.2 During laparoscopy, the biopsy forceps can be directed toward lesions of interest and to monitor for excessive bleeding. The liver biopsy can also be obtained with an ultrasonically activated scalpel.3 Ultrasound scalpels provide good tissue sampling for histologic analysis with minimal bleeding from the biopsy site. The amount of collateral tissue damage induced with an ultrasonically activated scalpel is similar to the damage induced by the cup biopsy forceps. The cup biopsy forceps causes crush injury to collateral tissue, whereas the ultrasound-activated scalpel causes thermal injury at collateral sites. The authors recommend the use of a 5-mm oval cup biopsy forceps for most liver biopsies, and the ultrasonically activated scalpel for biopsy of vascular masses involving the liver. Postbiopsy, the biopsy site must be closely monitored for excessive bleeding. The amount of bleeding associated with routine liver biopsy is usually minimal. If bleeding is considered to be excessive, several steps should be taken. First, the palpation probe can be placed into the biopsy site and pressure applied over the area with the tip of the probe. Alternatively, a small piece of saline soaked Gelfoam can be placed into the biopsy site using laparoscopic grasping or biopsy forceps. These options are sufficient to control excessive bleeding in most instances. In general, the liver should be biopsied on the surface and at an edge (Fig. 28-6), although some have suggested that edge biopsies may not reflect pathology of deeper samples because the subcapsular tissues are more reactive and fibrotic. It is always important to biopsy

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Figure 28-6  Biopsy of the liver with a 5-mm cup biopsy forceps.

Figure 28-8  Aspiration of the gallbladder with an 18-gauge spinal needle.

At the conclusion of the procedure, the instruments and telescope are removed and the pneumoperitoneum is vented. The cannulas are then removed and the puncture sites are sutured in a routine manner to conclude the laparoscopic procedure. For postoperative pain management, the authors recommend bupivacaine locally at the trocar cannula sites and also systemic analgesia (see Chapter 38).

PANCREAS Thomas Spillmann Figure 28-7  Severe dilation of the common bile duct in a patient with bile duct obstruction.

three to four areas of the liver, including areas that appear grossly normal as well as abnormal. The biopsy forceps cups should be tightly closed over the tissue biopsy for approximately 15 to 30 seconds before pulling the sample away from the liver.

Evaluation of the Biliary Tract The extrahepatic biliary tract can be examined during laparoscopy when the quadrate liver lobe is retracted toward the diaphragm. The hepatic, cystic, and common bile ducts can be evaluated for their size, color, shape, and patency. Dilation of the bile ducts is readily appreciated at the time of laparoscopy (Fig. 28-7). The size and health of the gallbladder can also be evaluated at the time of laparoscopy. A palpation probe is used to palpate the gallbladder to assess its stiffness or flaccidity. An 18-G spinal needle can be advanced percutaneously into the gallbladder to sample bile for culture and cytology, and to decompress the gallbladder and biliary system (Fig. 28-8). The needle has to be introduced in a location caudal to the insertion of the diaphragm. The line of insertion of the diaphragm on the last rib is outlined by a line of fat, which can be used as a reference point. If the needle is introduced through the diaphragm, there is a significant risk of inducing a pneumothorax with diffusion of CO2 under pressure from the abdomen. The gallbladder should be emptied as much as possible to prevent leakage of bile from the puncture site into the abdominal cavity.

The era of laparoscopy in human and veterinary medicine began in 1901 when Georg Kelling of Dresden, Germany, performed the first celioscopy in a dog.1,2 There were many anatomic descriptions reported thereafter, but it was not until 1957 that the use of laparoscopy in the diagnosis of intraabdominal disease was first reported. In that year, Hans Eikmeier of Giessen, Germany, published his habilitation thesis on the laparoscopic diagnosis of canine liver disease.3 The laparoscopic diagnosis of canine pancreatic diseases was first reported in the early 1970s, and the authors concluded that the technique might include the possibility of tissue sampling for histologic examination.4-6 With the advent of noninvasive abdominal ultrasonography, laparoscopy was nearly forgotten as a diagnostic tool. With renewed emphasis on minimally invasive procedures in both human and veterinary medicine, laparoscopy has experienced a resurgence of interest and application.7-10 The advantages of diagnostic laparoscopy in comparison to other advanced imaging techniques, such as contrast-enhanced computed tomography or endoscopic ultrasonography, are less-expensive equipment, technical ease of the procedure, and feasibility of direct sampling of biopsies from regions of interest.11-16

Indications Laparoscopic examination of the pancreas is indicated when the clinical signs, laboratory test results, and other imaging findings provide evidence for the existence of a pancreatic disorder that demands further macroscopic and histologic examination without an obvious need for diagnostic or therapeutic laparotomy.10,16-18

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SECTION III  Diagnostic Approach to Gastrointestinal, Pancreatic, and Hepatobiliary Problems

Tissue sampling at the time of laparoscopy enables the further differentiation of the many primary diseases of the pancreas and liver. In dogs, laparoscopy is used mainly to diagnose chronic pancreatic disease, such as chronic pancreatitis and subclinical pancreatic acinaratrophy.10,16-18 In cats, the addition of liver biopsy and laparoscopy-assisted small intestinal full-thickness biopsy to the procedure enables diagnosis of concurrent cholangiohepatitis, pancreatitis, and inflammatory bowel disease (termed “triaditis” by some authors).16,19,20

Contraindications and Limitations As with other laparoscopic procedures, the general contraindications for laparoscopic examination of the pancreas include poor patient condition with increased anesthetic risks, hemorrhagic diathesis, diaphragmatic hernia, abdominal effusion (especially septic peritonitis), abdominal adhesions, and renal, cardiac, or pulmonary insufficiency.10,16-18 The specific contraindications for laparoscopic examination of the pancreas include mass-forming pancreatic diseases (with or without extrahepatic biliary tract obstruction) such as pancreatic necrosis, pseudocyst, abscessation, and neoplasia. Mass-forming disease processes of the pancreas are better differentiated via laparotomy, which offers the possibility of immediate surgical intervention, such as debridement, omentalization, and resection of necrotic areas.21 Surgery also permits the restoration of patency to an obstructed common bile duct through surgical placement of temporary or permanent stenting.22 For pancreatic pseudocysts, surgical intervention is indicated when pseudocysts are symptomatic, in a phase of growth, complicated (infected, hemorrhagic, or associated with biliary or bowel obstruction), concurrent with chronic pancreatitis, and when malignancy cannot be excluded. Depending on the mode of presentation, cystic morphology, and available technical expertise, the recommended treatment options include percutaneous catheter drainage, duodenoscopy, or surgery.23,24 In dogs and cats, ultrasound-guided cystic puncture with cystic fluid evacuation has shown distinct clinical usefulness.25,26 Among surgical treatment options, cystoduodenostomy, cystic omentalization, and biliary diversion have a more favorable outcome than cystogastrostomy.27-29 The reader is referred to Chapter 60 for further information and detail. Multiple abdominal adhesions represent a general contraindication for many laparoscopic procedures.10,18 Unfortunately, there are no routine imaging techniques for the identification of pancreatic or peri-pancreatic adhesions prior to laparoscopy. If adhesions are encountered at the time of laparoscopy, a decision should be made to advance to laparotomy if the goals of laparoscopy cannot be achieved.

Technical Requirements Standard laparoscopic equipment is needed, including light source, automatic CO2-insufflation unit, endoscopy camera, monitor, and computer or video recorder for procedural documentation. Sterilized instrumentation needs to include a Veress insufflation needle and obturator, one optical trocar, one or two working trocars, a rigid laparoscope (0° or 30° viewing angle), and grasping and biopsy forceps.10,17,30,31 Use of a 10-mm–diameter optic containing an integrated working channel (Fig. 28-9) is well worth the investment. This particular instrumentation permits the pancreas to be maintained in place with a grasping forceps while taking a pancreatic biopsy through the working channel. If a more conventional optic is available, two

Figure 28-9  Hopkins straight-forward telescope with angled eyepiece and integrated instrument channel with inserted click line dissecting and biopsy forceps. (Courtesy of Karl Storz, Tuttlingen, Germany.)

working trocars will be needed to simultaneously negotiate the grasping (duodenal) and biopsy (pancreatic) forceps in the sampling of pancreatic tissue. Laparoscopy scissors are useful if small, nonvascular adhesions must be broken down.

Patient Preparation As with other laparoscopic procedures, patient screening should include complete blood count, serum chemistry, and coagulation times (prothrombin, partial thromboplastin, buccal mucosal bleeding) to assess for the risk of anesthesia and abnormal bleeding tendencies.10,17,30,31 Animals should be starved for a period of 12 to 18 hours prior to laparoscopy to ensure an evacuated upper gastrointestinal tract. Gaseous gastric distention can be managed with orogastric intubation in the anesthetized patient. To the extent possible, the distal colon/rectum and urinary bladder should be evacuated of feces and urine, respectively, before trocarization. Insufflation of CO2 into the abdominal cavity increases intraabdominal pressure (IAP), which may lead to spontaneous emptying of the urinary bladder when the patient is anesthetized. Therefore, it is recommended that a urinary catheter and collection system be placed in dogs prior to the procedure. This decreases the risk of accidental urine contamination of the operation field. Prior to laparoscopy, the operation field is prepared as for an aseptic laparotomy to allow immediate surgical intervention in case of pathologic findings or complications that demand a surgical approach.10,17,30,31

Anesthesia General anesthesia is necessary to perform laparoscopy. Canine patients can be premedicated with butorphanol and medetomidine, followed by anesthetic induction with propofol. Other induction protocols for dogs include a diazepam and l-methadone combination, or premedication with atropine, acepromazine, and morphine. Anesthesia is maintained with inhaled isoflurane (1% to 2%) in oxygen.17,32 In cats, induction can be performed with ketamine and xylocaine before intubation for isoflurane inhalant anesthesia. A study on the hemodynamic and respiratory effects of increased IAP and positive end-expiratory pressure in 10 healthy anesthetized

dogs undergoing laparoscopic pelvic lymphadenectomy revealed that an increase of IAP up to 15 mm Hg had no negative effect on the cardiovascular system. However, when increased IAP was combined with increased positive end-expiratory pressure (8 cm H2O), arterial CO2 and fractional end-tidal CO2 measurements revealed significant CO2 retention. Study results led to the recommendation for expanded cardiopulmonary monitoring during general anesthesia in high-risk patients.33 Another study assessed the cardiopulmonary effects of laparoscopic surgery in five dogs anesthetized with thiopental and maintained with halothane at 1.5 times minimal alveolar concentration in oxygen. Abdominal insufflation of CO2 to a pressure of 15 mm Hg for 180 minutes resulted in significant increases in heart rate, minute ventilation, and saphenous venous pressure, and decreases in pH and partial pressure of oxygen in arterial blood (PaO2). However, the observed changes were well within physiologically acceptable limits.34 Studies by the author in 23 dogs undergoing laparoscopy with an intraabdominal CO2 pressure of 11 mm Hg revealed no side effects of an anesthetic regimen using diazepam and l-methadone for induction and spontaneous, partly assisted isoflurane inhalation for maintenance of anesthesia. The same IAP can be used in cats. When possible, anesthetic monitoring should include clinical examination of reflexes, spontaneous breathing, and pulse, as well as pulse oximetry, capnography, and blood pressure measurement.17

Patient Positioning and Procedure For placement of the optic trocar, the dog or cat is placed in dorsal recumbency. When an optic trocar for a 10-mm optic is placed, a 1-cm–long incision is made into the skin over the linea alba with a scalpel about 1 cm caudal to the umbilicus. For smaller-diameter optics, the length of the skin incision is adjusted accordingly. In the center of the surgical wound, a Veress needle is pushed through the abdominal wall into the abdominal cavity to create a capnoperitoneum with an end IAP of 11 mm Hg. The Veress needle is removed and the optic trocar is put in place. After connecting the trocar with the automatic CO2 insufflator, the optic is introduced for the first general examination of the abdominal cavity. Using an endoscopic camera and monitor allows for a more convenient laparoscopic examination and better documentation of the findings than direct viewing through the optic. After the initial examination, a working trocar (5- or 10-mm diameter, depending upon patient size) is placed into the right cranial quadrant of the abdominal wall, several centimeters caudal to the last rib. The patient is then moved into slight left lateral recumbency (30° to 45°). In this position, the optic can still be moved easily but the small intestine can glide to the left side, giving view to the cranial duodenum and the pancreas on the right side. In some cases, it will be necessary to push the intestine to the left by introducing a grasping forceps through the working trocar or the working channel of the optic. When the pancreas is visible, a grasping forceps is introduced through the working trocar to grab the cranial duodenum close to the pylorus. Lifting the cranial duodenum toward the abdominal wall allows visualization of nearly the entire ventral part of the pancreas, except the distal tip of the left pancreatic lobe, which can be covered by the stomach and intestine, especially in large-breed dogs. Using the grasping forceps, the duodenum can be moved caudally to examine the dorsal part of the pancreas. Instrumentinduced trauma to the pancreas can be minimized by grasping the intestine only.

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Pancreatic Biopsies A pancreatic biopsy is not as dangerous as once thought, although biopsy of the pancreas should always have ample justification. Studies in healthy dogs and in dogs with pancreatic diseases, such as subclinical pancreatic acinar atrophy and chronic pancreatitis, show that multiple pancreatic biopsies taken via laparoscopy or laparotomy cause no serious complications. The danger of inducing acute pancreatitis is almost negligible.10,17,32,35-39 However, careful selection of the biopsy site is strongly recommended. Biopsies can be taken without apparent intra- or postoperative complications by using an endoscopic cup forceps,17 endoscopic Metzenbaum scissors distal to a tissue Endoclip, and sampling with a harmonic scalpel.32 Pancreatic biopsies should be taken from the margins of the organ or from macroscopically changed areas, avoiding deep tissue biopsies that might injure major vessels or pancreatic ducts (Fig. 28-10).10,17 Multiple biopsies should be taken even from macroscopically inconspicuous areas, as pancreatic inflammation tends to occur in discrete areas within the pancreas rather than diffusely throughout the entire organ. Single biopsies are seen as insufficient to exclude pancreatitis.40 Histologic assessment can be carried out according to a recently suggested grading system for nonneoplastic lesions of the exocrine pancreas. The histologic grading scheme includes scoring the biopsy for neutrophilic inflammation, lymphocytic inflammation, pancreatic necrosis, peripancreatic fat necrosis, edema, fibrosis, atrophy, and hyperplastic nodules.41

Laparoscopic Findings The normal pancreas has a pale cream color and is coarsely lobulated (Fig. 28-11). In some cases the pancreas can appear diffusely granulated, with no histologic evidence of an abnormality. Because a morphologically normal appearance does not exclude histologic abnormalities, multiple biopsies should be taken to confirm normality. Pancreatic pathology can vary in appearance. Loss of tissue can be a sign of pancreatic acinar atrophy of varying degree (Figs. 28-12 and 28-13). Histology helps to differentiate the finding from that of advanced chronic pancreatitis (Fig. 28-14). Swelling of the organ

Figure 28-10  Laparoscopic biopsy with an endoscopic cup forceps from a localized nodule of the pancreas of a Maine Coon cat histologically confirmed as focal chronic-purulent inflammation with fibrosis. (Used with permission from Rust S, Litzlbauer H-D, Burkhardt E, Moritz A, Spillmann T. Chronic pancreatitis, IBD and cholangitis in a Maine Coon cat. Kleintierpraxis 50: 171–182, 2005.)

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Figure 28-11  Laparoscopic picture from a Parson Russel Terrier with histologically confirmed normal pancreas.

Figure 28-12  Laparoscopic image from a German Shepherd dog with histologically confirmed partial pancreatic acinar atrophy. The exocrine pancreatic tissue is markedly reduced. (Used with permission from Spillmann T. Introduction and validation of modern laboratory and imaging techniques for the diagnosis of acute and chronic exocrine pancreatic diseases in dogs. Habilitation thesis [German], Büchse der Pandora Verlag, Wetzlar, p. 138, 2002.)

Rights were not granted to include this figure in electronic media. Please refer to the printed publication.

Figure 28-13  Laparoscopic image from a Hovawart dog with end-stage pancreatic acinar atrophy. The exocrine pancreas has completely disappeared. (Used with permission from Spillmann T, Moritz A, Burkhardt E. Diagnostic value of laparoscopy for pancreatic diseases in dogs. Tierarztl Prax 28[K]: 349–55, 2000.)

Rights were not granted to include this figure in electronic media. Please refer to the printed publication.

Figure 28-15  Laparoscopic picture of a mixed breed dog with histologically confirmed chronic pancreatitis. The image shows an adhesion of the right pancreatic (duodenal) lobe to the gastric wall. (Used with permission from Spillmann T, Moritz A, Burkhardt E. Diagnostic value of laparoscopy for pancreatic diseases in dogs. Tierärztl Prax 28[K]: 349–55, 2000.)

Figure 28-14  Laparoscopic image from a Cavalier King Charles Spaniel with severe loss of pancreatic tissue. The remaining pancreas is reddened and atrophied. Histology revealed chronic pancreatitis with marked interstitial fibrosis and severe atrophy.

Rights were not granted to include this figure in electronic media. Please refer to the printed publication.

Figure 28-16  Laparoscopy of a Cocker Spaniel one year after surviving severe necrotizing pancreatitis. The image shows marked adhesions of the pancreas to liver, duodenum, and omentum that hinder visualization of the pancreas. (Used with permission from Spillmann T, Moritz A, Burkhardt E. Diagnostic value of laparoscopy for pancreatic diseases in dogs. Tierarztl Prax 28[K]: 349–55, 2000.)

CHAPTER 28  Laparoscopy

can be a sign of acute or chronic pancreatitis. Adhesions with the surrounding organs or the abdominal wall have been reported in cats and dogs with chronic pancreatitis or as part of the healing process following acute necrotizing pancreatitis (Figs. 28-15 and 28-16).

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