Previous abil surgeryNo midline scars

A

= 10 mm

laparoscope or LUS-probe

B

10 mm

^ LUS-probe or laparoscope

C

5 mm

retraction . biopsy.

D

10 mm

= LUS [hepatoduodenal lig ]

of midline scars, the umbilical position is usually favored for establishing pneumoperitoneum and laparoscope placement. LUS examination of the liver requires access from the right subcostal region when using a (semi-)rigid probe, introduced laterally, between the midclavicular and anterior axillary lines. A second port is needed for full examination, preferably in the left subcostal or infra-umbilical areas. For LUS of the hepatoduodenal ligament, the transducer needs to be placed longitudinally and this requires access from the subxiphoid region. Usually two ports are sufficient although a third 5 mm trocar is useful for manipulation or retraction and for taking biopsies.

Diagnostic Laparoscopy

A systematic, thorough and unhurried visual exploration of the abdominal cavity is essential, and all peritoneal surfaces must be carefully examined to detect possible deposits. The undersurface of the diaphragm, the hepatic round ligament and the omentum require particular interest. Using a palpator and tilting the patient, the entire surface and all edges of both liver lobes must be closely scrutinized for evidence of metastatic disease. Lymph nodes in the hepatoduodenal ligament are examined for visible enlargement. Finally, the quality of the liver parenchyma with regard to the degree of cirrhosis or steatosis can be assessed.

Laparoscopic Ultrasonography (LUS)

We favor a slender (9 mm diameter, length 40 cm) rigid probe with a 7.5 MHz (38 mm) linear array transducer for ultrasound examination of the liver and bile ducts (Aloka UST- 5521-7.5, Tokyo, Japan) (Fig. 8.3). Fully-flexible endoscopes are more difficult to maneuver systematically over the liver surface. Although a

flexible tip may be useful, we do not find this to be essential. Curved array transducers provide distorted images of target lesions and are generally have a shorter field of view. The 7.5 MHz transducer provides superb resolution and, in our experience, has sufficient penetration depth of the liver parenchyma to allow complete imaging. In large right lobes, it may be helpful to place the probe on the undersurface of the liver. Ultrasound scanning is mainly done by direct contact with the liver surface. To achieve better contact between the rigid probe and the convex liver the abdomen is temporarily desufflated when necessary. Approximately 500 ml of normal saline solution is routinely installed in the upper abdomen to provide an acoustic window along the edges of the liver lobes and to improve contact in the case of (macronodular) cirrhosis. This also allows the standoff scanning technique necessary for examination of the structures of the hepa-toduodenal ligament. LUS of the liver

LUS of the liver is performed systematically in the same fashion as open IOUS and experience with the latter is essential. The smaller size of the LUS transducer compared to those used in IOUS requires consideration. The LUS probe is also more difficult to handle due to its limited maneuverability. However, the main difference is that LUS is done in a more longitudinal direction as opposed to the transverse orientation in IOUS. The laparoscope and LUS probe must be interchanged between the two ports to provide different views of the liver and to accommodate the varying placement of the probe on the liver surface. Creating a window in the falciform ligament allows the probe to be almost in a transverse plane facilitating orientation of the liver segments (Fig. 8.4). This may also be useful when there are dense midline adhesions preventing access to the left or right lobes. It is important to use gradual movements and gentle angulation or rotation of the LUS probe to provide clear images. Maintaining visual guidance of the probe's position on the liver with the laparoscope aids in orientation.

The first step in examination of the liver is to become acquainted with its segmental anatomy (according to Couinaud). The primary point of orientation is the convergence of the hepatic veins into the inferior vena cava (Fig. 8.5a). By following each of the individual right, middle and left veins peripherally the different segments are identified. Next, the portal vein confluence is found (Fig. 8.5b) by placing the probe on the anterior surface of the quadrate lobe (segment IV), and its right and left branches are followed. The caudate lobe (segment I) is seen between the portal vein and vena cava.

The second step in examination is the systematic, patient search for intrahe-patic lesions. The high resolution and ability to evaluate areas of interest in real time are the strengths of LUS. Not only is the interpretation of the acoustic shadowing more detailed, it is also possible to determine size and shape more accurately. The exact localization and relation to vascular structures is clearly defined (Fig. 8.6).

LUS of the gallbladder and proximal bile ducts

LUS of the gallbladder and proximal bile ducts is commenced by placing the probe on the anterior surface of segments IV and V, using the liver as an acoustic window. Imaging is performed in a variety of planes, with subtle rotary movements of the probe. The use of Doppler flow sampling helps to identify the different vascular structures. Scanning the gallbladder towards its neck will identify the

Fig. 8.6. Colorectal metastasis (M), 3 cm diameter, hepatic vein (RHV).

located in segment 7 with compression of the right

Fig. 8.6. Colorectal metastasis (M), 3 cm diameter, hepatic vein (RHV).

located in segment 7 with compression of the right cystic duct. Intrahepatic bile ducts are recognized by their hyperechoic walls (resembling tram-lines) and lie along corresponding hepatic artery and portal vein branches. These can be traced to reach the confluence of the left and right duct systems in the porta hepatis. The readily identified portal vein bifurcation is a convenient reference point. The portal vein exhibits a laminar flow which is low pressure and high velocity, in contrast to the pulsatile hepatic artery flow. The supraduodenal portion of the extrahepatic biliary tree is best examined with the probe longitudinal, through an umbilical port, and perpendicular to the hepa-toduodenal ligament, through a subxiphoid port. Transverse imaging provides the characteristic "Mickey Mouse" appearance of the common duct, hepatic artery and portal vein (Fig. 8.7a). The intrapancreatic portion of the common bile duct is identified by placing the probe over the head of the pancreas and first part of the duodenum. The subhepatic space should be filled with saline in order to create a better acoustic coupling.

Lymph nodes in the hepatoduodenal ligament are imaged directly, by the standoff technique, or through the left liver lobe. Their size, shape and echogenic structure are noted (Fig. 8.7b), which will suggest possible tumor infiltration.

Fig. 8.7a. Typical "Mickey Mouse" formation of the portal vein (PV), common hepatic duct (CHD) and hepatic artery (HA) seen on transverse imaging of the hepatoduodenal ligament. (IVC = inferior vena cava)
Fig. 8.7b. Lymph nodes (LN), 2 cm and 1.3 cm in diameter, in the hepatoduodenal ligament surrounding the portal vein (VP), common hepatic duct (DCH) and hepatic artery (AH).

Diagnosing Lesions/Biopsy Techniques: Visual aspect

All peritoneal deposits are best considered to be suspect and require biopsy to exclude malignancy (Fig. 8.8). Occasionally, benign mesothelial proliferations may appear as multiple peritoneal metastases. The degree of liver cirrhosis is determined. The visual aspect of lesions seen on the liver surface is often diagnostic. Cysts are greenish-blue in appearance when visible at the surface. Small metastases are usually easily identified and larger ones have a typical umbilicated or crater appearance. One pitfall is the "von Meyenburg complex", a small benign tumor which may appear as a nodule on the surface. It is indistinguishable from a metastasis visually, and often misleadingly diagnosed as malignant on frozen section. The recognition of satellite lesions is difficult when there are regeneration nodules in a cirrhotic liver. Visually guided (fine needle or core) biopsy is often unavoidable.

Ultrasonographic Aspect

While most intrahepatic lesions can be characterized by their specific sonographic appearance, very small (< 5 mm) solid benign tumors cannot be differentiated from metastases. Hepatic cysts are a common finding (10% of the normal population) and can usually be defined preoperatively. However, smaller cysts (less than 1 cm) escape detection or cannot be differentiated externally. The typical US features are a smooth, often spherical, thin-walled lesion, sonolucent with posterior acoustic enhancement (Fig. 8.9a). Hemangiomas are also frequent and appear as dense echoic areas with minimal shadowing, and do not produce distortion of the surrounding tissue structures (Fig. 8.9b). Compressibility is a characteristic feature. Focal nodular hyperplasia (FNH) is often confused with metastatic disease although there may be a typical bright hyperechoic center in a hypoechoic, well-defined lesion. Adenomas are usually diagnosed preoperatively

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