Pancreatic fistula

　　Most of the pancreatic fistula is caused by postoperative complications of acute severe pancreatitis, and can also be caused by trauma, or after pancreatic biopsy. It is common in pancreatic surgery, pancreatic trauma, acute pancreatitis, and after pancreatic biopsy. The following will introduce the causes of pancreatitis fistula.

　　1. Pancreatic trauma

　　This is the most common cause of pancreatic fistula, with an incidence of about 14.4% to 37.2%. This is mainly due to:

　　① After the pancreas is damaged, especially by blunt trauma, the actual range of tissue damage is often larger than that seen with the naked eye. Therefore, if this factor is ignored during debridement or repair of the pancreas, the residual damaged pancreatic tissue may continue to necrose after surgery, and once it involves the pancreatic duct, a pancreatic fistula will occur.

　　② Although the damaged pancreatic duct seen during surgery is ligated, if secondary infection occurs after surgery, it is still easy to develop a pancreatic fistula.

　　③ Damage to the main pancreatic duct, if the pancreatic duct is of normal size, it is difficult to achieve success in pancreatic duct anastomosis, and pancreatic fistula is likely to occur. If it is directly drained externally, pancreatic fistula may also occur after surgery.

　　2. Acute necrotizing pancreatitis

　　Due to local ischemia and the digestive action of enzymes, the pancreas tissue and pancreatic ducts can necrose. After the necrotic pancreas tissue is surgically removed or spontaneously shed, the pancreatic duct is exposed outside, or after pancreatectomy of the body and tail of the pancreas, due to unhealed tissue infection, the secretion of the pancreas continues to flow out through the drainage orifice, causing a pancreatic fistula. In acute necrotizing pancreatitis, the incidence of pancreatic fistula is about 15%.

　　3. Pancreatic surgery

　　All types of pancreatic surgery can potentially damage the pancreatic duct, leading to the formation of a pancreatic fistula. After pancreatectomy with duodenum resection, about 10% to 25% of cases develop a pancreatic fistula, which is the most serious complication of this surgery and also the main cause of death after pancreatectomy with duodenum resection. Most cases are due to technical errors in the anastomosis between the residual pancreas and the digestive tract after pancreatectomy with duodenum resection. The incidence is related to the surgical method, the treatment of the residual pancreas, and the thickness of the pancreatic duct. Generally, the incidence of pancreatic fistula after pancreatic head resection is higher than that after distal resection, and the incidence of pancreatic fistula after pancreatic duct ligation is higher than that after pancreaticojejunostomy; the incidence of pancreatic fistula with normal pancreatic duct diameter is higher than that with明显扩张的。Islet cell tumor surgery usually involves tumor resection and is less likely to damage the pancreatic duct. If the tumor is located deep or close to the main pancreatic duct, it may damage the pancreatic duct and cause a pancreatic fistula if not careful during surgery. In addition, if the location is deep during pancreatic wedge resection biopsy and coarse needle aspiration cytology examination, it may also damage the pancreatic duct. If the tail of the spleen is too long or too thick, it may also be damaged during splenectomy or splenorenal venous anastomosis.

　　The above is the cause of pancreatitis fistula, which is very helpful for understanding the disease. The disease can be caused by complications of pancreatic surgery, and strict operation requirements must be followed during pancreatic surgery.

　　The accumulation of pancreatic juice in the peritoneal cavity in patients with pancreatic fistula can cause necrosis of surrounding tissues, easily leading to secondary infection. After infection, the activation process of pancreatic enzymes accelerates, enhancing the digestive and corrosive effects of pancreatic juice. Rupture of the gastrointestinal tract can cause bleeding and internal fistula in the stomach, small intestine, colon, and other parts. If a blood vessel is ruptured, it can cause fatal massive hemorrhage. Weak and low-resistance patients may develop uncontrollable multiple abscesses in the abdominal and retroperitoneal areas, and quickly appear multiple organ dysfunction and even death.

　　Pancreatic fistulas can be classified into high-flow and low-flow fistulas according to the daily drainage volume of pancreatic juice, and can also be divided into mild pancreatic fistula (100ml/d), moderate pancreatic fistula (100-500ml/d), and severe pancreatic fistula (500ml/d). Early mild pancreatic fistula may only manifest as an increase in amylase in the drainage fluid without other symptoms. Early severe pancreatic fistula often presents with marked abdominal tenderness, tachycardia, tachypnea, or mild restlessness in patients, or with signs of peritonitis when complicated with infection. The amylase in the drainage fluid is often significantly increased, but this is not an indispensable characteristic. The loss of a large amount of pancreatic juice containing water, electrolytes, and proteins, if not supplemented in time, can cause dehydration and electrolyte imbalance, as well as obstacles in the digestion and absorption of nutrients, manifesting as weight loss and malnutrition. The loss of excessive alkaline pancreatic juice can lead to metabolic acidosis. Swelling and erosion of the skin around the fistula opening can lead to ulcers and even bleeding. It can also be due to poor drainage, where the skin of the fistula heals before the pancreatic fistula, forming a pseudopancreatic cyst.

　　1. Pancreatic internal fistula

　　After the pancreas forms an internal fistula with the duodenum or upper jejunum, the leaked pancreatic juice directly enters the intestinal tract, which can alleviate the symptoms and signs of the original pseudopancreatic cyst or infected peripancreatic abscess, and even heal spontaneously. If there were no obvious clinical manifestations originally, and the formation of the internal fistula did not cause complications such as hemorrhage or infection, the patient would not have any special manifestations. When a colonic fistula is formed, due to the loss of pancreatic juice, it can cause varying degrees of hyponatremia, hypokalemia, and hypocalcemia, as well as dyspepsia, metabolic acidosis, malnutrition, and other symptoms.

　　2. Pancreatic external fistula

　　Most cases occur after surgery, and it is generally believed that 1 to 2 weeks after surgery are the high-risk period for pancreatic fistula. Low-flow pancreatic fistula or small pancreatic fistula can cause changes in the skin around the external fistula opening, but generally no other clinical manifestations. High-flow pancreatic fistula or medium to large pancreatic fistula can present with clinical manifestations similar to those of colonic fistula. The leakage fluid from pure pancreatic external fistula that does not communicate with the gastrointestinal tract is colorless and transparent clear liquid, with a pancreatic amylase content of 20,000 U/L (Sotiaux units, etc.), and when mixed with lymphatic leakage fluid, the amylase content is 1000 to 5000 U/L. When the leakage fluid is turbid, bile-colored, green, or brown, it indicates that pancreatic juice has mixed with intestinal juice, pancreatic enzymes have been activated, and their corrosive nature may cause tissue damage, massive bleeding, and other complications. If complications such as hemorrhage, infection, or intestinal fistula occur, there will be corresponding clinical manifestations. When the pancreatic fistula drainage is not smooth, patients may experience symptoms such as abdominal pain, fever, muscle tension, and leukocytosis.

　　Feihua Health Network reminds you:Common diagnostic methods for pancreatic fistula include CT, endoscopic retrograde cholangiopancreatography (ERCP), and fistula angiography.

　　Eliminate the related etiology of pancreatic fistula (such as mechanical causes such as trauma or surgery, or the rupture of the pancreatic duct due to acute and chronic pancreatitis), to avoid the occurrence of pancreatic fistula.

　　The key to preventing the occurrence of pancreatic fistula lies in good pancreatojejunal anastomosis techniques and methods during surgery, and the correct postoperative management is an important guarantee for reducing the incidence of fistula. Firstly, it is necessary to strengthen the improvement of pancreatojejunal anastomosis techniques, secondly, attention should be paid to the management of the pancreatic duct, thirdly, postoperative drainage must be kept unobstructed and effective, fourthly, the patient's overall condition should be improved to promote the healing of the anastomosis.

　　Pancreatic fistula is the most common complication after pancreaticoduodenectomy. The management of the pancreatic stump is the key to preventing the occurrence of pancreatic fistula after pancreaticoduodenectomy. The pancreatic stump should be cut into a fish mouth shape and sutured at the margin. When anastomosing the pancreatic stump with the jejunum, it should be avoided to tear or injure the pancreas. At the same time, the patency of the pancreatic duct should be maintained. It is routine to place a stent tube in the pancreatic duct to effectively introduce pancreatic juice into the intestinal lumen or drain it out of the body, reducing the stimulation of pancreatic juice on the anastomosis, and avoiding accidental injury to the pancreatic duct during surgery. The anastomotic segment to be anastomosed should ensure sufficient length and good blood supply. Regardless of the anastomosis method between the pancreas and jejunum, it is necessary to ensure that the anastomosis is tight, reliable, and tension-free. After the anastomosis is completed, it should be ensured that there are no obstructive factors in the intestines. The placement of the pancreatic duct stent tube should be noted:

　　Choose a stent tube that is suitable for the diameter of the pancreatic duct, avoiding it being too thick or too thin, to prevent twisting and obstruction. Prevent the pancreatic juice from渗入吻合口而不利于吻合口愈合 by seeping along the outer wall of the stent tube. The stent tube outside the pancreas should have a certain length, and there should be no lateral holes on the tube wall. The pancreatic duct stent tube should be properly fixed to avoid early tube dislodgment, and the stent tube with external drainage should be removed 3 to 4 weeks after surgery.

　　The method of pancreatojejunostomy is also very important for the occurrence of pancreatic fistula. Theoretically, mucosal-to-mucosal anastomosis can better drain pancreatic juice into the intestinal lumen, reducing the stimulation of pancreatic juice on the anastomosis. However, since end-to-side anastomosis and sleeve anastomosis are performed under different conditions, it is still not clear in clinical practice which method is more beneficial in preventing the occurrence of pancreatic fistula. Generally, when the diameter of the pancreatic duct is greater than 0.5 cm, end-to-side anastomosis is more effective, and it should not be forced to perform end-to-side anastomosis when the diameter is less than 0.5 cm. It is better to perform sleeve anastomosis when a stent tube is placed in the pancreatic duct.

　　During distal pancreatectomy, fibrin glue can be used to seal the pancreatic stump to prevent the formation of postoperative pancreatic fistula. After transecting the pancreas, the main pancreatic duct is ligated with non-traumatic suture, and then the residual end of the pancreas is sutured continuously and overlapped. Finally, 2ml of fibrin glue is applied to the suture site. There is also the use of alcohol-soluble gliadin glue to segmentally occlude the pancreatic duct to prevent the formation of postoperative pancreatic fistula after distal pancreatectomy. The pancreas is transected bluntly, and the incision surface is shaped like a concave fish mouth. The main pancreatic duct is left with an incision surface of 5mm. At 2cm near the incision edge, the pancreas is clamped with a non-traumatic forceps, and 0.2ml of alcohol-soluble gliadin glue is injected into the main pancreatic duct. Then it is ligated and purse-string sutured, and the pancreas incision is sutured after the glue hardens. Both methods are effective and no toxic reactions have been observed.

　　A pancreatic fistula occurs when pancreatic juice leaks out through a non-physiological route after the rupture of the pancreatic duct. The one that leaks out into the outside of the body is called an extrapancreatic fistula, and the one that flows into the digestive tract is called an intrapancreatic fistula. Extrapancreatic fistula is a serious complication in pancreatic surgery. The treatment of pancreatic fistula is relatively difficult, and improper treatment can easily cause serious complications such as hemorrhage and infection, even death. The early clinical manifestations of pancreatic fistula are often not very typical, and its diagnosis mainly relies on laboratory examination of the drainage fluid and modern imaging and endoscopic examination. The specific examination of this disease is as follows.

　　1. Measurement of amylase levels in the drainage fluid

　　It is one of the simple and useful diagnostic methods for pancreatic fistula, but it is necessary to differentiate between pancreatic leakage and pancreatic fistula, the former being more common after pancreatectomy with duodenal drainage, and the fluid around the anastomosis often contains a high level of amylase, but it gradually decreases. If the drainage is not smooth or secondary infection occurs, it can lead to poor healing of the anastomosis and transform into a pancreatic fistula. If the amylase concentration in the postoperative drainage fluid is more than three times the normal plasma concentration and lasts for more than 7 days, it should be considered as the presence of a pancreatic fistula, especially if the amylase concentration in the drainage fluid on the first day after surgery is greater than 4000 units, it should be regarded as a valuable predictor of pancreatic fistula. The measurement of amylase concentration in the drainage fluid is an important criterion for judging the presence of a pancreatic fistula, while the concentration of plasma amylase is often within the normal range during a pancreatic fistula.

　　2. Imaging examination

　　(1) B-ultrasound:

　　Due to its low cost, non-invasive nature, it is one of the routine examinations for suspected pancreatic fistula patients and can be used to explore the shape of the pancreas, whether there is peripancreatic effusion, and whether there are pancreatic cysts, and it can be used as a preliminary examination of the pancreatic and biliary duct system. However, for patients who are overweight, have a large amount of gas in the gastrointestinal tract, and have a history of abdominal surgery, B-ultrasound examination is more difficult.

　　(2) CT, MRI examination:

　　It is further possible to observe whether there is deformation of the pancreas and pancreatic duct, whether there is peripancreatic effusion and cyst formation, and particularly the relationship between the pancreatic duct and the leakage site or cyst, which is superior to B-ultrasound.

　　(3) Retrograde Pancreatography (ERCP):

　　ERCP is an important examination method for displaying the anatomical structure of the pancreatic and biliary ducts. Direct observation of the location, extent, and anatomical relationship between the pancreatic duct and the fistula can be made through pancreatic and biliary ductography, especially to determine the cause and classification of the pancreatic fistula.

　　(4) Magnetic Resonance Cholangiopancreatography (MRCP):

　　Magnetic resonance cholangiopancreatography (MRCP) is a high-quality three-dimensional imaging of the pancreatic and biliary ducts without the need for contrast agents, with no injury, and can clearly show the pancreatic and biliary duct tree, the anatomical structure of the pancreatic duct, and the relationship between the pancreatic duct and peripancreatic effusion, which plays a guiding role in subsequent treatment. It is particularly applicable to those who have failed ERCP or are contraindicated. ERCP and MRCP have high value in diagnosing pancreatic fistula and can complement each other's deficiencies, but correct choices should be made according to specific circumstances.

　　(5) Fistulography:

　　For cases that have become chronic fistulae, fistulography can be performed, which is the simplest method. Fistulography can show the size, course, and relationship with the pancreatic duct of the fistula, and clearly indicate whether there is stenosis of the pancreatic duct or ampulla.

　　The above are the examination methods for pancreatic fistula. Through these examinations, a diagnosis of pancreatic fistula can be made. If a patient has a pancreatic fistula, they need to be treated actively and strive to avoid life-threatening situations.

　　The diet of patients with pancreatic fistula should be light and balanced. In some cases of pancreatic fistula, there may be malabsorption of fat, so it is necessary to reduce the intake of fat to avoid diarrhea caused by fat intake. It is not advisable to eat high-fat foods and fried foods during diarrhea, and cooking various dishes should be as oil-free as possible, and it is recommended to often use steaming, boiling, stewing, blanching, and braising. Contraction drinks such as black tea and rice porridge can be used, and snacks should be small and frequent to increase nutrition.

　　Patients with pancreatic fistula should avoid eating coarse fiber foods in daily diet, such as radishes, coarse grains, dried beans, chives, and other foods should be avoided as much as possible. This can effectively alleviate the symptoms of pancreatic fistula and help in the treatment of pancreatic fistula.

　　Patients with pancreatic fistula should try to eat less spicy and刺激性 foods, as these foods are easy to stimulate the intestines, leading to further aggravation of the condition. Therefore, patients with pancreatic fistula should eat less wasabi, chili, alcohol, and other spicy and刺激性 foods.

　　Patients with pancreatic fistula are prone to diarrhea, so attention should be paid to the hygiene of daily diet, and at the same time, it is also necessary to eat less cold and raw foods, as these foods are difficult to digest and easy to stimulate the intestines, causing diarrhea, so they should be eaten in small amounts.

　　Seafood is prone to cause allergies, so in order to prevent patients from exacerbating the inflammatory response due to the consumption of seafood, patients should minimize the intake of seafood and, at the same time, it is best not to drink too much milk to reduce the adverse symptoms of the pancreatic fistula.

　　The treatment principles for pancreatic fistula primarily involve inhibiting pancreatic secretion, including extracorporeal nutrition support, inhibiting pancreatic enzyme activity, and using somatostatin analogs. The next step is the drainage of the pancreatic fistula, which includes various percutaneous catheter drainage, surgical drainage, and endoscopic drainage.

　　1. General management

　　Fasting and gastrointestinal decompression can reduce the stimulation of gastrointestinal fluid on the pancreas, which is beneficial in the early stages of pancreatic fistula. Attention should be paid to correcting water and electrolyte imbalances in patients with high-flow pancreatic fistula to maintain homeostasis in the body.

　　2. Nutritional support

　　Patients with high-flow pancreatic fistulas often experience a large amount of pancreatic juice leakage, affecting the patient's digestive and absorptive functions, leading to malnutrition. Active supplementation of calories, vitamins, and proteins should be provided to improve the overall condition and promote the healing of the pancreatic fistula. It has been proven that tumor necrosis factor can inhibit pancreatic exocrine secretion, reduce the amount of fistula drainage, and shorten the time for fistula closure. In addition, enteral nutrition is also increasingly gaining attention, as enteral nutrition can promote the recovery of intestinal function, protect the intestinal mucosal barrier, prevent bacterial translocation, and is beneficial for preventing the occurrence of systemic inflammatory response syndrome and multiple organ failure.

　　3. Prevention and treatment of infection

　　Pancreatic fistula complicated with infection often leads to serious consequences and has a high mortality rate. The drainage fluid should be routinely cultured for bacteria and drug sensitivity tests, and antibiotics should be chosen reasonably. In the absence of culture results, empirical use of antibiotics can be made first, with most infections initially caused by Gram-negative bacteria and anaerobic bacteria, and the first choice of treatment is third-generation cephalosporins or aminoglycosides plus metronidazole or quinolones.

　　4. Somatostatin analogs

　　The main effect of somatostatin analogs in the treatment of pancreatic fistula is to inhibit pancreatic secretion and relax the smooth muscle of the intestinal tract, which can significantly reduce the incidence of pancreatic fistula and accelerate the closure of the fistula. A randomized, prospective clinical study found that the prophylactic use of somatostatin can reduce the incidence and mortality of pancreatic fistula after selective pancreatic resection.

　　Martineau et al. analyzed the literature and reported that somatostatin analogs as adjuvant therapy can reduce the incidence of postoperative pancreatic fistula and have the effect of accelerating fistula healing, but their effect on recent pancreatic fistulas with a course of less than 8 days is poor.

　　5. Percutaneous catheter placement and surgical drainage

　　Pancreatic fistula can be drained through percutaneous insertion of a drainage tube to promote the closure of the fistula opening. However, due to the digestive and corrosive effects of pancreatic juice on local tissues, there are issues such as a long drainage time and slow healing of the fistula, especially for pancreatic fistulas communicating with the main pancreatic duct, which are not very effective.

　　6. Endoscopic treatment of pancreatic fistula

　　Pancreatic fistula refers to pancreatic pseudocyst. Dell Abate performed endoscopic drainage on 15 patients with pancreatic pseudocyst, with an average hospital stay of 4.8 days and a mortality rate of 0%, indicating that endoscopic drainage is effective for pancreatic pseudocysts compressing the gastrointestinal tract. Sciume reported a success rate of 88% (7/8) for endoscopic drainage. Libera compared the results of endoscopic drainage via the ampulla and through the gastric wall and found no significant difference between the two, with high success rates and low incidence of complications. De Palma conducted a long-term follow-up of patients with pancreatic pseudocysts undergoing endoscopic drainage, comparing the effects of drainage via the gastric wall and the ampulla. Twelve patients experienced complications, including hemorrhage (2 cases), mild pancreatitis (2 cases), and cyst infection (8 cases), with 9 patients suffering recurrence of pseudocyst. After a follow-up of 25.9 months, 75.5% of the patients were effectively treated.

　　7. Endoscopic Treatment of Extra-Pancreatic Fistulas

      For pancreatic fistulas communicating with the main pancreatic duct, endoscopic nasal pancreatic duct negative pressure drainage can be performed to drain pancreatic juice to the outside to promote fistula closure, or endoscopic placement of pancreatic duct stents for drainage can be performed to promote fistula closure.

　　(1) Endoscopic Nasal Pancreatic Duct Drainage:

　　Sun Zhiwei in China reported that 8 patients with pancreatic fistula were treated with nasal pancreatic duct negative pressure drainage, and the fistula healed in 6 to 28 days, but the nasal pancreatic duct is easy to fall off, and it cannot solve the root problem of pancreatic duct stenosis. Brelvi reported on 3 patients with chronic pancreatitis associated with long-term alcohol abuse, 2 of whom had difficulty breathing and chest pain, with imaging suggesting pleural effusion. ERCP found that the fistula led from the pancreatic duct to the pleural cavity, and another patient had left upper abdominal pain and a small amount of pleural effusion, with a pseudocyst adjacent to the stomach. The first two were treated with nasal pancreatic duct drainage and thoracic duct drainage, and the patient with a pseudocyst underwent transgastric nasal cyst drainage. The fistula closed within 7 days, the pseudocyst absorbed within 14 days, and all three had no pain episodes, and there were no recurrences of pseudocysts and fistulas after discharge.

　　(2) Pancreatic Duct Stent Drainage:

　　Endoscopic placement of pancreatic duct stents for drainage can relieve pancreatic duct stenosis and obstruction, allowing for smooth drainage of pancreatic juice, a rapid decrease in the amount of external drainage of pancreatic fistula, and the rapid closure of the fistula.

　　Kozarek et al. treated a patient with pancreatic fistula who was ineffective after conservative treatment with pancreatic duct stent, and the fistula healed 10 days after the stent was placed, with no recurrence or other complications.

　　(3) Biological Glue Occlusion of Fistula:

　　Traditionally, due to the formation of pancreatic fistula caused by pancreatic necrosis, the treatment methods are long-term percutaneous catheter drainage or open drainage after surgery, but part of the pancreatic function is lost after surgery, and there is also the risk of secondary infection and venous thrombosis. Findeiss used biological glue to occlude the fistula, and the patient had no symptoms in the following year, and no drainage tubes or other interventional operations were needed.

　　The above are the treatment methods for pancreatic fistula. If you have a pancreatic fistula, you need to seek active hospital treatment as soon as possible.