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Holzheimer RG, Mannick JA, editors. Surgical Treatment: Evidence-Based and Problem-Oriented. Munich: Zuckschwerdt; 2001.

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Surgical Treatment: Evidence-Based and Problem-Oriented.

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Fistulas of the pancreas

, M.D.

Department of Surgery, University of Manitoba, Winnipeg, Canada

Introduction

Disruptions of the main pancreatic duct, smaller ducts or pancreatic parenchyma cause external or internal pancreatic fistulas. A pancreatico-cutaneous fistula results when the exocrine secretions leak through a drain site or a wound. If the secretions extravasate within the pancreatic parenchyma or the peri-pancreatic tissues and are walled-off by the inflammatory process, a pseudocyst occurs. Pancreatic ascites is the result of a free leak into the peritoneal cavity, and pleural effusions may form as the secretions track in the retroperitoneum upwards, through the diaphragm, and into the mediastinum and pleural space. Rarely, pancreatic secretions may extravasate into a hollow viscus, forming a pancreatico-enteric fistula.

Pancreatico-cutaneous fistula

An external pancreatic fistula is, by definition, drainage of pancreatic fluid through an abdominal wound or drain tract persisting for more than 7 days. The most common cause is complication of pancreatic surgery or percutaneous catheter drainage of pseudocysts. Sepsis, electrolyte disturbances, and skin excoriation are common in high output fistulas (more than 200 ml per day). The management is initially conservative, as spontaneous closure can be expected in the majority of cases, especially in low-output fistulas. Imaging by means of fistulogram and CT scan may be useful. Initial therapeutic measures include total parenteral nutrition, electrolyte, replacement, skin protection, and administration of the somatostatin analogue octreotide. Refractory cases should be subjected to endoscopic retrograde pancreatography (-ERP) and surgery. Distal pancreatectomy is reserved for fistulas of the tail. Fistulas originating from the head, neck, or body are usually treated by Roux-en-Y pancreatico-jejunostomy to the fistulous tract itself and some cases require proximal pancreaticoduodenectomy.

Pseudocysts

Pseudocysts are fluid collections, usually inflammatory in origin, that arise in or in close proximity to the pancreas; by definition, they lack an epithelial lining. Most pseudocysts are seen in the context of either acute or chronic pancreatitis. A small proportion of pseudocysts are post-traumatic. In children, trauma is the most common aetiology of pancreatic pseudocysts. The pseudocyst of acute pancreatitis is an extra-pancreatic, loculated collection of fluid rich in amylase that develops within 2 weeks of the onset of the attack. It probably results either the disruption of a pancreatic duct or from leakage from the inflamed surface of the gland. A ductal communication is exceptionally demonstrable. Most such peri-pancreatic “acute fluid collections” resolve spontaneously unless they contain a large amount of necrotic material or become infected. Some persist and acquire a wall of fibrous or granulation tissue. The pseudocysts of chronic pancreatitis may result from one of two pathogenetic processes, firstly, a necrotic collection may develop as a complication of an attack of acute-on-chronic pancreatitis and secondly, a retention collection may occur as a result of blockage of a major branch of the pancreatic duct by localized fibrosis, a calculus, or a protein plug, leading to the rupture of the corresponding acini. Especially in this variety, the pseudocyst is intra-pancreatic and a communication with the duct is demonstrable in a significant minority of cases. Post-traumatic pseudocysts develop as the result of ductal disruption or seepage from a capsular tear of the gland. Collections complicating these latter minor leaks may resolve spontaneously.

The clinical presentation of a pseudocyst consists of any combination of the following: failure of the initial abdominal pain to resolve within 7–10 days, presence of an epigastric mass, persistently raised serum amylase level, obstructive symptoms such as vomiting or jaundice, and signs of intra-abdominal infection. The diagnosis is firmly established via ultrasound or CT scan. More uncommon modes of clinical presentation include, variceal bleeding secondary to splenic or portal vein obstruction and evidence of intra-abdominal haemorrhage secondary to bleeding from a pseudoaneurysm in adjacent visceral vessels. Sometimes the pseudocyst is asymptomatic and discovered in the course of the work-up of a patient with chronic pancreatitis. Differential diagnostic difficulties may arise in ruling out pancreatic cystic neoplasms. The clinical context is important. When a clear history of pancreatitis is lacking, spiral CT scan and cystic fluid analysis may often solve the diagnostic dilemma. Pseudocyst fluid is rich in amylase while neoplasm fluid contains tumor markers and sometimes characteristic cells. Mucinous carcinoma sometimes present on a background of pancreatitis, and a small proportion of these cystic tumors communicate with the duct. Nonetheless, cyst wall biopsy is resorted to in rare cases.

Spontaneous resolution is more likely in acute than in chronic pseudocysts. Certain criteria suggest that a pseudocyst will not resolve spontaneously: persistence of an acute pseudocyst for more than 6 weeks, evidence of chronic pancreatitis, pancreatic duct abnormality other than communication with the pseudocyst, ultrasonographic evidence of a thick wall. Size alone may not be a good indicator of spontaneous resolution. However, asymptomatic pseudocysts smaller than 6 cm in diameter can be treated conservatively. Treatment aims to evacuate the contents of the pseudocyst and prevent the complications of rupture, infection, haemorrhage, and biliary or intestinal obstruction. There is a wide range of therapeutic options available, including percutaneous drainage, surgical procedures and endoscopic management.

Simple aspiration of pseudocysts is attended by an unacceptably high rate of recurrence. However, percutaneous pigtail catheter drainage has an important place in the therapeutic armamentarium. A communication between the pseudocyst and the main pancreatic duct as demonstrated by ERP or by subsequent cystograms via the catheter track has an important influence on the effectiveness of this method. The presence of such a communication does not necessarily preclude drainage but may require prolonged drainage and predisposes to external fistulisation. Retroperitoneal, transperitoneal, transgastric, transhepatic, and transduodenal percutaneous routes have all been used successfully. It has been claimed that the transgastric route has the advantage of resulting into a cysto-gastric fistula, allowing internal drainage in those cases with an occluded pancreatic duct.

Resection is reserved for a minority of chronic pseudocysts. It is more readily used in distal than in proximal pseudocysts. Compelling factors in favor of resection include intractable pain from chronic pancreatitis, multiple pseudocysts, gastrointestinal haemorrhage from a pseudo-aneurysm, and common bile duct or duodenal obstruction. Longitudinal pancreatico-jejunostomy is added in the pancreatic remnant if the main duct is dilated. Most cases subjected to surgery are offered drainage rather than resection. External drainage is the operation of choice for infected pseudocysts, those with an immature soft wall that would not hold sutures or when emergency laparotomy is undertaken for haemorrhage or free rupture. This option is often complicated by a pancreatic fistula the which if it persists, requires either distal pancreatectomy or Roux-en-Y pancreatico-jejunostomy. The most commonly performed operation for mature uncomplicated pseudocysts is internal drainage by anastomosing the pseudocyst to the stomach, the duodenum or a jejunal Roux-en-Y loop. It is can be performed in chronic cases as soon as they are diagnosed, but; in acute cases; a delay of 4–6 weeks from diagnosis is required to allow for pseudocyst wall maturation. Roux-en-Y cystojejunostomy is generally preferred to cystoduodenostomy or cystogastrostomy as it affords better dependent drainage, is attended by fewer complications (haemorrhage, abscess, or fistula formation) and a lower rate of recurrences. Bleeding from a pseudo-aneurysm in the wall of the pseudocyst is relatively rare but is also attended by a high mortality rate. This has led to the recommendation that selective angiography and embolization, if necessary, always be performed before embarking on an internal drainage procedure.

At present, there are no strict guidelines about choosing between operative and percutaneous catheter drainage. It seems that, for infected pseudocysts, catheter drainage is superior to laparotomy with external drainage. It has been suggested that the best results of catheter drainage in noninfected pseudocysts are obtained in cases without demonstrated communication with the duct or ductal obstruction.

Endoscopic drainage techniques are gaining ground steadily. They consist of transpapillary drainage and transmural techniques (cystoduodenostomy or cystogastrostomy). Transpapillary drainage is a technically demanding procedure and possible only when there is a communication between main pancreatic duct and pseudocyst. This requirement is more commonly fulfilled in chronic than in acute pancreatitis. Complications of stenting include pancreatitis, stent occlusion or migration, ductal stricture, and duodenal erosion. Transmural drainage is reserved to pseudocysts located in the pancreatic head or body; these must be thin-walled and seen clearly at endoscopy to be bulging into the gastrointestinal lumen. These minimally invasive endoscopic techniques yield good results in expert hands when patients are carefully selected.

Pancreatic ascites and pleural effusions

Most of these cases are seen in the context of chronic alcoholic pancreatitis, although a definite history of pancreatitis may be absent. A minority of cases are post-traumatic. Ascites and pleural effusions coexist in 25% of patients. Pancreatic ascites presents clinically as a massive abdominal distention often initially mistaken for alcoholic cirrhotic ascites. Diagnosis is made on the high albumin content (more than 3 g/100 ml) and amylase level (more than 1000 U/l) in the ascitic fluid and, frequently the presence of hyperamylasaemia. Pancreatic pleural effusions present with chest pain, dyspnea, or cough. The same laboratory findings are characteristic of pleural fluid.

Initial non-operative management may result in resolution in 40–60% of cases, but recurrences are not uncommon. A therapeutic trial of parenteral nutrition and ocreotide should be instituted for a maximum of 3 weeks aimed at resting the gland and decreasing pancreatic secretion. Repeated paracentesis or thoracocentesis may be indicated for symptomatic relief and to encourage apposition of the serosal surfaces. Failure of this conservative management or recurrence are indications for surgery. The anatomy of the pancreatic duct should be delineated first by ERP. Distal pancreatectomy is reserved for distal disruption of the main duct. Pancreatic duct leaks in the more proximal aspects of the gland are treated with Roux-en-Y pancreatico-jejunostomy to the site of pancreatic duct or pseudocyst disruption. There may be a place for low-dose irradiation (3–5 Gy) of the pancreas in patients unresponsive to conservative treatment and too unfit for surgery. Peritoneo-venous shunting is another option in this context. Transpapillary endoprosthesis have been used more recently in ductal disruptions. These either occlude the site of ductal disruption or bypass the sphincter, thus converting the duct into a low-pressure system.

Pancreatico-enteric fistula

The uncommon entity of pancreatico-enteric fistula is produced by spontaneous rupture of a pancreatic pseudocyst or abscess into an adjacent hollow viscus. Most commonly, these fistulas occur between the pancreas and the splenic flexure or transverse colon. Less frequently involved organs include the stomach, duodenum, small bowel, and extrahepatic biliary tree. Symptomatic pancreatic pseudocysts have rarely been reported cured by spontaneous decompression into an enteric structure. In most cases, however, spontaneous rupture of a pseudocyst or abscess into a hollow viscus is associated with sepsis or bleeding, and appropriate operative intervention becomes necessary. In a small number of cases, percutaneous drainage of pseudocysts is complicated by such fistulas. Catheter erosion in the face of ongoing pancreatitis may be the cause. These patients can often be treated non-operatively with a combination of catheter removal and ocreotide, sometimes supplemented with endoscopic transpapillary stenting.

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Copyright © 2001, W. Zuckschwerdt Verlag GmbH.
Bookshelf ID: NBK7003

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