Pancreatic fistula overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
A pancreatic fistula is an abnormal communication between the pancreas and other organs due to leakage of pancreatic secretions from damaged pancreatic duct. An external pancreatic fistula is one that communicates with the skin, and is also known as a pancreaticocutaneous fistula, whereas an internal pancreatic fistula communicates with other internal organs or spaces. Pancreatic fistulas can be caused by pancreatic disease, trauma, or surgery. Pancreatic fistula can be classified anatomically as internal fistula and external fistula. Pancreatic fistula can also be classified based on the anatomy of the pancreatic duct and the location of injury as Type 1 pancreatic fistula, Type 2 pancreatic fistula and Type 3 pancreatic fistula. The disruption of the pancreatic duct either from an iatrogenic insult, underlying inflammatory process or trauma results in the leakage of the pancreatic fluid inducing inflammation and erosions, thereby forming abnormal connections with the surrounding structures. The etiology of pancreatic fistula include iatrogenic and non-iatrogenic insults. Differential diagnosis of pancreatic fistula may include chronic liver disease, renal failure, heart failure, malignancy, pleural effusion, pancreatitis, retroperitoneal bleeding and bowel ischemia. The incidence of pancreatic fistula following pancreatic resection surgery varies from 5% to 26%. The overall mortality risk due to pancreatic fistula is 1%, however patients with grade C pancreatic fistula carries a mortality risk of 25%. According to Fistula Risk Scoring (FRS) system, the risk factors for the development of pancreatic fistula depends upon the texture of the gland, underlying pathology, diameter of the pancreatic duct, underlying carcinoma involving the pancreatic duct, intraoperative blood loss and other risk factors such as male gender, obesity, malnutrition, increase gland remnant volume, fasting blood glucose level <108 mg/dl and excessive fluid administration during surgery. Clinical presentation may range from being asymptomatic to showing a variety of signs and symptoms resulting from fluid accumulation such as nausea, vomiting, hypotension, infection, tachycardia, pain, weight loss, ileus and severe symptoms such as unrelenting pain and sepsis. External pancreatic fistula presents with pancreatic fluid accumulation noticeable on the skin surface. Internal pancreatic fistula may present with ascites or pleural effusion as fluid accumulates within the abdominal or thoracic cavity. Complications following a pancreatic fistula may include Wound infection and sepsis, Hemorrhage, Internal and/or external fistula, Pancreatic pseudocyst, Delayed gastric emptying, Walled off pancreatic necrosis, Prolongation of the hospital stay, Pancreatic ascites, High amylase pleural effusion, Disconnected duct syndrome, Multisystem involvement eventually leading to multiorgan failure and/or death. Pancreatic fistula that are less severe are reported to heal in a duration of 4-6 weeks with conservative management only. 80% of the external fistula and 50-65% of the internal fistula are reported to close eventually with conservative measures which involve stabilization of the patient with supportive therapies. However, pancreatic fistula can lead to significant morbidity if not addressed on time. Surgical intervention provides resolution of the fistula with a 90-92% success rate. A pancreatic fistula with leakage of fluid can be diagnosed in some cases with typical history and clinical presentation, such as patient presenting with pancreatitis followed by recurrence, persistent symptoms or post pancreatic resection fluid drainage with increase amylase level. Patients diagnosed with pancreatic fistula are sometimes asymptomatic while some patients may present with symptoms such as marked recent weight loss, unresponsiveness of the ascites to diuretics, non-specific symptoms such as nausea, vomiting, hypotension, infection, and tachycardia and some patients with a high grade fistula may present with sepsis. Patients with pancreatic fistula usually appear normal and in some they appear malnourished. Physical examination of patients with pancreatic fistula is usually remarkable for infection, dyspnea, pleuritic chest pain and ascites. Pleural or ascitic fluid should be sent for analysis. An elevated amylase level, usually > 1,000 IU/L, with protein levels over 3.0 g/dL is diagnostic. Complete blood count is necessary to check for any ongoing infection or hemorrhage. Complete metabolic panel including inflammatory markers, serum electrolytes, liver function tests, calcium, albumin, amylase and lipase should be sent to laboratory for evaluation. Furthermore, pancreatic fistula leak presenting as ascites or pleural effusion should be analyzed for fluid protein, albumin, lactate dehydrogenase, glucose, gram cultures and total cell count. Thoracopancreatic fistula may lead to pleural effusion which can be detected incidentally on a plain chest radiograph. Pancreatic fistula can be diagnosed using abdominal CT scan as it is primarily used to rule out other causes of the abdominal discomfort. The CT scan may demonstrate fluid collections in the thoracic or abdominal cavity or changes associated with acute or chronic pancreatitis leading to pancreatic fistula. Magnetic resonance imaging can be used to predict the formation of pancreatic fistula by calculating the pancreatic remnant volume (PRV) and measuring the width of the pancreatic duct at the line of resection. Endoscopic retrograde cholangiopancreatography (ERCP) is used to diagnose as well as treat the fistula with placement of pancreatic stent during the procedure. ERCP demonstrate filling of the pancreatic duct with contrast and extravasation of the contrast suggesting disruption of the pancreatic duct. Pancreatic fistula is a known complication following a pancreatic surgery. Post operation management is focused towards prevention of complications arising as a consequence of pancreatic secretion from an anastomotic stump or the surface of skin which can subsequently complicate into intraabdominal abscess formation or life threatening hemorrhage. To reduce the risk of development of a post-operative pancreatic fistula, prophylactic measures such as nutrition support, prophylactic somatostatin analogues, drain management and a post-operation follow up is taken to reduce the risk of pancreatic fistula formation. Treatment of pancreatic fistula includes early recognition of the problem which is the key to careful management in order to prevent the consequent complications. Medical therapy is tailored towards the suppression of pancreatic enzymes by restricting the patient's oral intake of food in conjunction with the use of long-acting somatostatin analogues such as octreotide. Correction of the fluid and electrolyte abnormalities. The patient's nutrition is maintained with total parenteral nutrition. This treatment is continued for 2-3 weeks, and the patient is observed for improvement. Patients with expanding peripancreatic fluid on abdominal imaging or with persistent symptoms undergo endoscopic therapy via endoscopic retrograde cholangiopancreatography (ERCP) as it is a preferred approach towards the management of a symptomatic pancreatic fistula due to its diagnostic as well as therapeutic value. A transpapillary pancreatic stent is placed during ERCP and/or a pancreatic sphincterectomy is done. If no improvement is seen or endoscopic therapy is not feasible, the patient may receive surgical treatment. Surgical treatment depends upon the location of the fistula where the duct is disrupted, the size of the peripancreatic fluid collection, presence of vascular thrombosis, tissue necrosis and history of previous interventions. Surgical treatment may involve the drainage of pancreatic pseudocyst if indicated, which is often associated with chronic pancreatic fistula. Other options may include fistulojejunostomy, pancreatic resection and decompression of the pancreatic duct with pancreatojejunostomy.