Pancreatic fistula
| Pancreatic fistula | |
| MeSH | D010185 |
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Pancreatic fistula Microchapters |
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Diagnosis |
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Treatment |
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Case Studies |
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Pancreatic fistula On the Web |
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American Roentgen Ray Society Images of Pancreatic fistula |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
A pancreatic fistula is an abnormal connection between the epithelialized surfaces of the pancreatic duct and adjacent or distant structures, organs or cavities. Clinical criteria defined by the International Study Group for Pancreatic Fistula (ISGPF) is a measurable drain output containing pancreas-derived enzyme amylase which is greater than three times the upper limit of the normal serum level measured on or after postoperative day three. A revised grading for pancreatic fistula was proposed by ISGPF, according to which pancreatic fistula is graded either into a new category which involve an asymptomatic leakage from the pancreas called biochemical leak (BL), or Grade B including patients who undergo surgical procedures such as percutaneous or endoscopic drainage or angiographic procedures in order to promote the healing of fistula and Grade C including patients with organ failure requiring reoperations and mortality as a result of complication from pancreatic fistula.
Historical Perspective
Classification
Pancreatic fistula can be classified anatomically as;
- Internal fistula: The pancreatic duct communicates with internal organs or body cavity such as pleural or peritoneal cavity.
- External fistula: The pancreatic duct communicates with the skin, otherwise known as pancreaticocutaneous 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: Involves injury to the pancreatic parenchyma with leakage from the distal part of the pancreatic duct or the side branches.
- Type 2 pancreatic fistula: Involves injury to and leak from the main pancreatic duct.
- Type 3 pancreatic fistula: Occurs as a result of proximal or distal pancreatectomy.
Pancreatic fistula is classified into two categories on the basis of clinical manifestations, complications and severity by the ISGPF as;
- Biochemical pancreatic fistula: This category includes fistula with no significant clinical symptoms.
- Clinically relevant pancreatic fistula: This category includes fistulas under grade B and C, which shows significant clinical symptoms and require surgical interventions, re-surgeries and can complicate into organ failure and death.
Pathophysiology
The pathophysiology of pancreatic fistula involves the disruption of the pancreatic duct either from an iatrogenic insult, underlying inflammatory process or trauma. The disruption of the pancreatic duct causes gradual loss of the integrity of the tissue resulting in the leakage of the pancreatic fluid which induces inflammation and erosions, thereby leading to the formation of abnormal connections between the duct and the surrounding structures.
Causes
Pancreatic fistula can result from different types of insults such as;
- Iatrogenic: External pancreatic fistula is most commonly iatrogenic in etiology. Trauma to the duct during surgery such as pancreaticoduodenectomy, distal pancreatectomy, during endoscopic intervention, extraction of a biopsy sample, pancreatic resection or as a complication of drainage of pancreatic pseudocyst.
- Non-iatrogenic: Includes pathology of the gland such as acute or chronic pancreatitis or trauma to the abdominal structures or organs leading to fistula formation.
Differentiating Pancreatic fistula from other Diseases
Differential diagnosis of a pancreatic fistula may include evaluation for:
- Chronic liver disease leading to abdominal ascites
- Renal failure
- Heart failure
- Malignancy
- Conditions leading to pleural effusion such as malignancy, trauma and infections
- Pancreatitis
- Retroperitoneal bleeding
- Bowel ischemia
Epidemiology and Demographics
Pancreatic fistula is a known complication following surgical resection of the pancreas. The incidence rate varies from as low as 5% in high volume centers to as high as 26%. Acute fluid collection is recorded in up to 40% patients with acute pancreatitis, out of which some cases develops true pancreatic fistula depending upon the severity of the insult. Post-operative pancreatic fistulae can affect 13% to 41% of patients after pancreatic resection, making it a known source of morbidity and mortality. Pancreatic fistula can lead to certain severe complications if not addressed on time, as it carries a mortality risk of 25% in patients with grade C pancreatic fistula. The overall mortality rate is 1%. The incidence of pancreatic fistula varies depending on the type of pancreatic resection as it can be as low as 3% following a pancreatic head resection to as high as 30% after distal pancreatectomy.
Risk Factors
According to Fistula Risk Scoring (FRS) system, the risk factors for the development of pancreatic fistula depends upon:
- Texture of the gland: Soft texture of the gland is identified as a predictive risk factor.
- Pathology of the gland: Carcinoma of the duodenum, ampulla, cystic duct and islet cell carries high risk for fistula development compared to the glandular carcinoma such as pancreatic ductal adenocarcinoma or chronic pancreatitis.
- Diameter of the pancreatic duct: Small pancreatic duct diameter <3mm is identified as a risk factor for the development of fistula formation, specifically a diameter of <1mm carries a high risk.
- Intraoperative blood loss: >1000ml is associated with a high risk of fistula formation.
- Other risk factors may include male gender, excessive fluid administration during surgery, fasting blood glucose <108 mg/dl and an increase remnant gland volume. Some studies have reported both malnutrition and obesity as risk factors for the development of pancreatic cancer.
Natural History, Complications and Prognosis
History and clinical presentation depends upon the size, location and connection of the pancreatic fistula with the involved organ or cavity.
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 arising from a pancreatic fistula are due to the undrained pancreatic fluid accumulation and erosions caused by the enzymatically active substances of the fluid which affects the surrounding tissues. The most commonly observed complications are:
- 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.
Diagnosis
History and clinical presentation:
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. However, most cases are far more challenging which require imaging techniques and examination of the fluid samples withdrawn from the leak to help diagnose the fistula.
Imaging:
The imaging techniques used to confirm the diagnosis of pancreatic fistula may include abdominal ultrasound, CT-scan of the abdomen, pancreatogram, endoscopic retrograde cholangiopancreatography (ERCP), magnetic resonance cholangiopancreatography (MRCP) and fine needle aspiration of the fluid using endoscopic ultrasound (EUS). ERCP can be used for both diagnosis and therapeutic purposes such as placement of stent during the procedure to facilitate the closure of fistula.
Laboratory tests:
Fluid samples collected via thoracentesis, paracentesis or fluid collected via percutaneous drainage from an external fistula can be analyzed for amylase level, which helps solidify the diagnosis of pancreatic cancer. 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. To differentiate the ascites or pleural fluid from pancreatic fluid the fluid amylase level will be >1000 u/dl.
Treatment
Treatment of a pancreatic fistula includes early recognition of the problem which is the key to careful management in order to prevent the consequent complications. Management of pancreatic fistula requires a multidisciplinary team which includes interventional radiologists, endoscopy specialist and surgeons and include the following steps:
- Biochemical leak: Patients with biochemical leak are clinically asymptomatic with an amylase rich pancreatic fluid drain and can be managed conservatively. Patients should be kept under observation with close monitoring for signs of complications in order to avoid its progression to clinically relevant pancreatic fistula. The drain placed intraoperatively are usually kept to support the spontaneous closure of the fistula. Drainage output and inflammatory markers such as C-reactive protein and leucocyte count are regularly monitored to prevent fluid collections that may lead to life threatening sequalae.
- Grade B or C pancreatic fistula:
- Non-Surgical approach: Primary management involves treatment with non-surgical minimally invasive catheter drain placement. Imaging techniques such as CT-scan in combination with interventional drain placement can help resolve peri-pancreatic fluid collection that went unrecognized and developed eventually. Antibiotic treatment is given to prevent abdominal infections. One life threatening condition that may complicate a grade B or C fistula is hemorrhage of a nearby vessel by the enzymatically active pancreatic fluid, which can be promptly evaluated with the help of CT-angiogram to identify the location of the bleeding vessel and can be managed via angiographic placement of a stent or embolization.
- Surgical management: Conditions which requires urgent evacuation of large amount of blood that cannot be attained with minimally invasive techniques necessitates surgical interventions which include emergency laparotomy, intra-abdominal lavage and drainage of infected fluid collections widely. Conditions which involves necrosis, life threatening sepsis or complicated pancreatic fistula may require the resection of the remnant pancreas.
Supportive care which is proven beneficial for both biochemical leaks and patients who develop sepsis and/or hemorrhage as a complication of pancreatic fistula include stabilizing the patient, pancreatic secretion control, nil per oral by ideally starting temporary parenteral nutrition and correction of the fluid and electrolytes abnormalities. Somatostatin analogs such as octreotide are used commonly to control the pancreatic secretion, however no significant benefit is observed with its use in patients with already established pancreatic fistula.