Liver And Hepatoduodenal Ligament

Before removal of the liver, the hepatoduodenal ligament should be dissected. First, the common bile duct is incised and

Fig. 5-4. Posterior view of portions of liver, pancreas, and spleen. Note presence of micronodular cirrhosis. The splenic vein has been opened and the confluence with the portal vein the superior mesenteric vein is shown, together with the partially opened inferior vena cava.

opened toward the hilus and the ampulla of Vater. The lowermost portion of the common bile duct runs retroduodenally. The duodenum must be pulled in the anterior direction and somewhat to the left if the common bile duct is to be exposed in its full length without cutting into the wall of the duodenum. Again, the best specimens can be prepared after formalin fixation. In fetuses and newborns, dissection of the common bile duct is difficult, and its patency is easier to check by opening the duodenum and observing whether bile can be milked out through the papilla. This is a useful test, particularly when biliary atresia is suspected.

The hepatic artery lies to the left of the common bile duct and can easily be dissected from the anterior aspect of the hepatoduodenal ligament. For the demonstration of the portal vein and its tributaries or of the inferior vena cava, dissection from the posterior aspect gives the most instructive results (Fig. 5-4). In these instances, en bloc or en masse removal (page 3) is recommended.

SLICING It is almost impossible to slice livers with normal-sized knives without leaving knife marks on the cut surface. Smooth cut sections of cirrhotic livers are even more difficult to prepare. We use a knife with a 78-cm blade (its use for lungs is illustrated Chapter 4, Fig. 4-5), which in most instances permits slicing of the whole organ with an uninterrupted pulling motion.

Usually, the liver is sliced in the frontal plane, each slice being about 2 cm thick. The hilar structures may remain attached to one of the central slices. However, it is sometimes necessary to expose, on one cut section, a large parenchymatous surface or leave the hilar structures intact. In these instances, horizontal sections through the liver is the methods of choice (Fig. 5-5). We routinely slice livers in this manner if they had been prefixed in our cascade perfusion system (see below).

FIXATION The cascade perfusion system for lungs that is described in Chapter 4, works also very well with surgically removed livers that are obtained from the liver transplant program. The failure rate with autopsy livers is greater than the rate with surgically obtained livers, undoubtedly because of postmortem clotting. Nevertheless, if the recently described methods are applied properly, many autopsy livers can be fixed successfully with this machine. For the preparation of large histologic sections, perfusion fixation of the whole liver yields the best results. If large slices of fresh livers are placed in a formalin bath, the fixative often does not penetrate deep enough. If the slices are only 3-4 mm thick, they fix readily but usually with considerable distortion.

GROSS STAINING FOR IRON This method (11) is used particularly in cases of genetic hemochromatosis. Excessive hemosiderin storage in other organs (pancreas, myocardium) also can be demonstrated by this technique. The actual staining procedure is described in Chapter 14, page 133.

HEPATIC ARTERIOGRAPHY, PORTAL VENOGRAPHY, AND CHOLANGIOGRAPHY Barium sulfate gelatin mixtures give excellent results. For angiography, it is safe to remove the liver together with the diaphragm, the hepatoduodenal ligament, and a long segment of inferior vena cava. Vessels or bile ducts can be injected with contrast medium either before or after perfusion fixation. Fig. 5-6 (A) shows nozzles that are needed for the infusion of the contrast medium. The figure (Fig. 5-6, B) shows such a nozzle in place. After the vessels

Fig. 5-5. Cutting a perfusion-fixed liver in a horizontal plane. Note that the rims of the metal tray are used to guide the long-bladed knife. Adapted with permission from ref. (10).

have been cannulated, blood and blood clots are flushed out with saline. Cholangiography is facilitated if a sufficiently long sleeve of the common hepatic duct remains attached so that a cannula can easily be tied into the lumen. Removal of the gallbladder prior to cholangiography may lead to leakage of contrast medium from the gallbladder bed and therefore it may be better to fill the gallbladder together with the bile ducts (Fig. 5-7); it can be removed after the gelatin has solidified. If the contrast mixture has a low gelatin content and thus low viscosity, small vessels and ducts (below 100 pm diameter) can be filled. In autopsy livers, cholangiography sometimes leads to simultaneous filling of portal vein branches, probably because of auto-lytic changes. This is not observed in surgically removed livers.

For the preparation of hepatic venograms, see below under "Renal Venography."

Preparation of Corrosion Casts Vinylite corrosion and Latex injection are the most commonly used methods. Differently colored media often were used to identify the various vascular compartments and the bile ducts. Details of the methods are supplied by the factories that sell the plastic.

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