Damaged pancreatic ducts that disrupt the normal communication between the pancreas and other organs in the body are responsible for causing a pancreatic fistula.
Internal Pancreatic Fistula
An internal pancreatic fistula involves an abnormality in the way that the pancreas communicates with organs and spaces within the body. This is usually due to a disrupted pancreatic duct or psuedocyst leakage.
Depending on the pancreatic secretion flow, it may result in several complications, including:
- Pancreatic ascites
- Mediastinital pseudocysts
- Enzymatic mediastinitis
- Pancreatic pleural effusions
External Pancreatic Fistula
Also known as a pancreaticocutaneous fistula, an external pancreatic fistula is an abnormality in the communication between the pancreatic duct and the exterior of the body or skin.
This occurs due to a loss of bicarbonate-rich pancreatic fluid leading to anion gap metabolic acidosis, which may or may not be hypercholaemic. Losing a small volume of fluid doesn’t usually have a noticeable effect, but when a large volume is lost acidosis is more common.
The most common cause of internal pancreatic fistula is pancreatitis, which disrupts the pancreatic duct. In adults, this usually occurs as a result of excessive alcohol use, whereas in children it is much more common to be as a result of some physical trauma. A cyst may also be responsible for causing the condition.
The progression to a pancreatic fistula begins with disruption within the pancreas due to a cyst or duct blockage. This leads to pancreatic secretions leaking into the free peritoneal cavity or the mediastinum, depending on where the disruption occurs. This may eventually result in pancreatic ascites or enzymatic mediastinitis and it is also common to the pleura to form a chronic pancreatic pleural effusion within the chest.
Symptoms and Diagnosis
People affected by pancreatic fistula usually experience significant weight loss. To aid in diagnosis a distinctive characteristic of the condition is unresponsiveness to diuretics.
To make an accurate diagnosis, pleural or ascetic fluid needs to be analyzed. The level of amylase is indicative of the condition, with raised levels greater than 1000 IU/L. Additionally protein level in excess of 3 g/dL suggests involvement of pancreatic fistula.
Serum levels may also show elevation of amylase, as the enzyme tends to cross the peritoneal or pleural surface into the systemic circulation.
Finally, some imaging techniques may help in the diagnostic process. Contrast-enhanced computed tomography is often used and endoscopic retrograde cholangiopancreatography (ERCP) can aid in both diagnosis and treatment of the condition.
The initial step for the treatment is to manage the oral intake of food to suppress the production of pancreatic enzymes. This is often maintained with the use of total parenteral nutrition that is continued for 2 to 3 weeks. Simultaneously, long acting somatostatin analogues can assist this effect and reduce enzyme production even further.
During this time, the patient should be observed for signs of improvement. If there is no evidence of improvement after this time, surgical or endoscopic treatment may be able to offer a solution. If this is needed, an ERCP is needed to determine the location of the leak.
When the affected area is identified, fisulectomy is conducted and the removal of part of pancreas is conducted.