Atlas of General Surgical Techniques (Courtney M. Townsend Jr., B. Mark Evers)

The anterior superior and the posterior superior pancreaticoduodenal arteries also arise from branches of the gastroduodenal artery. These arteries form an arch medial to the C-loop of the duodenum, and they collateralize with branches of the anterior and posterior inferior pancreaticoduodenal arteries, which are branches of the superior mesenteric artery. Small branches from these arteries provide blood supply to the duodenum.

Key anatomic features in pancreatic head resections are the network of tributaries projecting between the superior mesenteric vein/portal vein confluence and the uncinate process. These tributaries are located at the right lateral aspect of the veins. These tiny veins exit the pancreas at the mid-portion of the groove in which the major veins reside.

Viewed in cross-sectional imaging, the uncinate process forms a C-shaped structure. The terminal posterior extent of the uncinate process projects in a medial direction as a ligamentous structure and contains a variable number of arterial branches from the superior mesenteric artery that project at right angles to the major artery and provide blood supply to the uncinate process. Division of the tiny venous tributaries and the arterial branches are key steps in respective procedures. This uncinate margin is the most problematic in managing malignant tumors in the head of the pancreas.

The pancreas is entirely retroperitoneal, and therefore operative procedures will require mobilization of the pancreas from its retroperitoneal position. The plane lateral to the C-loop of the duodenum is incised in nearly all procedures, and this plane is avascular and its mobilization is termed the Kocher maneuver. This exposes the vena cava and aorta and it permits “bimanual palpation” of the head of the pancreas. The dissection may be easily extended to the fourth portion of the duodenum and the ligament of Treitz .

The inferior border of the body of the pancreas is also avascular, although the inferior mesenteric vein may be encountered to the right of the spine.

Peritoneum overlies the hepatoduodenal ligament. Dissection reveals the triad in gross anatomic terms, which corresponds to the microscopic portal triad—with portal, hepatic arterial, and biliary structures. The common bile duct is located in an anterior lateral position, and the hepatic artery is anterior medial. The portal vein is positioned in the posterior groove created by the apposition of these anterior structures.

Although lymph nodes may be seen at a wide array of locations, there is a constant lymph node in the groove created by the lateral border of the second portion of the duodenum and the hepatoduodenal ligament. Dissection of this lymph node is necessary to fully visualize the proximal hepatic artery. Other common sites of lymph nodes are on the lateral aspect of the mid-portion of the hepatoduodenal ligament, in the fibrovascular bundle surrounding the right gastroepiploic complex, and on the superior border of the confluence of the head and body of the pancreas. Beneath this lymph node one finds the origins of the common hepatic artery and the splenic artery.

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On the inferior border of the pancreatic head, just where the duodenum dives beneath the superior mesenteric vein and artery, one may dissect the peritoneum and visualize the superior mesenteric vein as it passes in a superior direction beneath the head of the pancreas.

The ligament of Treitz is a significant anatomic structure, and it can be accessed by lifting the transverse colon and omentum in an anterior direction. The ligament can be seen to the left of the spine.

The main pancreatic duct originates in the tail of the pancreas and traverses the length of the pancreas to exit in the duodenum through both main ampulla (Vater) and the accessory ampulla, which is located more proximally in the duodenum. The main pancreatic duct (Wirsung) and the minor or accessory duct (Santorini) fuse during fetal development at what is termed the genu or “knee” of the duct.

It should be understood that pseudocysts can form at any location including sites quite remote from the pancreas itself. Thus certain pseudocysts may involve anatomy not included in this review.

INDICATIONS

The indication for operation in pseudocysts is somewhat complex.

First, one must confirm that the pseudocyst has persisted long enough to be certain that the cyst will not simply spontaneously resolve.

Although not uniformly accepted, there is literature suggesting that only symptomatic pseudocysts should be treated. Thus one indication for surgery is symptoms (daily pain or difficulty eating, or recurrent attacks of acute pain).

The generally stated indication for surgery or some form of intervention is the development of the complications of pseudocysts (obstruction of intestine or bile duct, hemorrhage into the pseudocysts, infection in the pseudocysts, and rupture of the pseudocysts). Rupture of a pseudocyst will present as ascites, an entity termed pancreatic ascites. A ruptured pseudocyst should be suspected when this entity is identified.

An additional indication may be rapid expansion in a pseudocyst.

An important distinction that should be made in the preoperative evaluation is the possibility that a cyst actually represents a neoplastic cyst. In this case, suspicions may be raised by the fact that a cyst has septations; a cyst has what appears to be wall thickening within the cyst; and the patient may have an elevation in the tumor marker, which is known as CA 19-9. Particularly in the setting of acute pancreatitis, one cannot automatically exclude a cystic neoplasm, because 37% of patients with a diagnosis of intraductal papillary mucinous neoplasm (IPMN) present with pancreatitis. In the event that a neoplastic cyst is suspected, then

preoperative aspiration, typically by means of endoscopic ultrasound, is useful. This cyst fluid should be examined for the presence of mucin confirmed by mucicarmine staining, measured for carcinoembryonic antigen (CEA) level, and sent for cytopathologic evaluation.

STEP 2: PREOPERATIVE CONSIDERATIONS

We strongly advocate identification of the pancreatic ductal anatomy before intervention for pseudocyst, and we have published several papers delineating the reasons. One particularly significant reason to evaluate the ductal anatomy is to help direct the choice of modality to treat the pseudocyst. At this time, there is literature supporting three separate modalities to treat pseudocysts (surgery, endoscopy, and interventional radiology). Our data suggest that certain ductal injuries will make the likely success of these nonoperative modalities unacceptably low. We also advocate defining ductal anatomy to recognize the possible coexistence of a diagnosis of chronic pancreatitis, which should be addressed with operative procedures intended to treat that diagnosis rather than simply treating the cyst.

We generally advocate a cystojejunostomy over the use of cystogastrostomy. There are strong data to suggest that a very large cyst has a high likelihood of sepsis after cystogastrostomy, and there are softer data suggesting that cystogastrostomy has a higher risk of postoperative hemorrhage compared with cystojejunostomy.

If one is considering a cystogastrostomy, cross-sectional imaging is vital to confirm a fusion of the plane between the pseudocyst and the posterior wall of the stomach. Crosssectional imaging will also confirm a close adherence between the pseudocyst and duodenum if a cystoduodenostomy is considered. Finally, cross-sectional imaging may help in directing dissection for entering a cyst for cystojejunostomy. For example, the presence of a cyst posteriorly toward the tail of the pancreas may be best addressed by traversing the transverse mesocolon in order to access the cyst. If the cyst is posterior to most of the parenchyma of the pancreas, it may be necessary to dissect beneath the pancreas rather than to incise through normal pancreatic parenchyma to access the cyst.

Be sure that your imaging is recent. In the event that a month or more has elapsed since the last imaging, there is a possibility that the cyst has changed or disappeared entirely.

We perform a bowel preparation and a colonic cleansing in all patients.

Within 1 hour of surgery, a single intravenous dose of a second-generation cephalosporin is given.

STEP 3: OPERATIVE STEPS

1.INCISION AND EXPOSURE

We use an upper abdominal midline incision, although subcostal or transverse incisions may be preferable depending on the location of the cyst and the anticipated mode of bypass. We use self-retaining retractors to afford visualization.

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2. DISSECTION

Cystogastrostomy

When the decision is made to proceed with cystogastrostomy, the operative procedure is fairly simple (Figure 51-1). Two stay sutures of 3-0 silk stitch are placed in the anterior wall of the stomach after palpating the cyst to confirm the incision will be placed exactly over the primary palpable body of the pseudocyst. After these two sutures are placed on the superior and inferior margin of the anticipated gastrotomy, electrocautery is used to perform an anterior gastrotomy for a length of approximately 8 cm. After this is done, one can easily palpate the connection between the pseudocyst and the posterior wall of the stomach

(Figure 51-2).

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At this point, a 20-gauge angiocatheter is placed into the cyst to confirm that cyst fluid will be encountered (Figure 51-3). Finally, electrocautery is used to begin an entryway through the posterior wall of the stomach into the cyst. We then take a long, delicate hemostat such as the Seurat clamp and gently place it through the posterior wall of the stomach and through the anterior wall of the cyst. Typically a large amount of fluid will be evacuated. In most cases, this will result in fairly significant collapse of the pseudocyst. At this point of entry, a larger orifice can be made, and at the same time a biopsy of the wall of the cyst can be obtained (Figure 51-4). This should be sent for frozen section analysis to confirm that it is not a neoplastic cyst. We finally work with approximately 3-cm-diameter entry into the cyst. Next, 2-0 Prolene sutures are used in a running fashion to complete the connection between the cyst and posterior wall of the stomach (Figure 51-5). After this is complete, one evacuates any solid material within the cyst and irrigates the cyst. For all cysts, we believe it is vital to evacuate as much of this debris as possible. Any hemorrhage encountered in the wall of the cyst or in the gastric wall should be suture ligated to prevent postoperative hemorrhage.

Angiocatheter

FIGURE 51–3

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We often will take a culture of the fluid in the cyst on the chance that the cyst fluid has been colonized (which is common) and the patient develops signs of sepsis in the postoperative period.

The anterior gastrotomy is then closed in two layers with an outer layer of interrupted 3-0 silk stitch and an inner layer of a Connell type of absorbable suture, such as polydioxanone (PDS) or Vicryl. Lembert sutures of 3-0 silk are placed at the two corners of the gastrotomy, tied, and left long on a hemostat for traction. Two 3-0 Vicryl sutures are placed and tied at each corner with the knot on the inside. A Connell type of running inverted stitch is used, starting at each corner and meeting in the middle of the gastrotomy and tied (Figure 51-6). Finally, an interrupted 3-0 silk stitch is used in an interrupted fashion to complete the anterior layer of the gastrotomy closure (Figure 51-7).

We do not use drains. The peritoneal cavity is irrigated.

Fascia is reapproximated in the normal fashion, and subcuticular sutures are placed in the skin.