Intestinal Fistula

　　There are many causes of small intestinal fistula, which can be roughly divided into surgery, injury, disease-induced, and congenital, among which the vast majority are caused by surgery.

　　1. Surgical cause: surgery is the most common cause of small intestinal fistula.Wang Julin and others from Xi'an Medical College reported that 95.1% of the 82 cases of small intestinal fistula admitted from 1957 to 1983 were postoperative. Roback and others reported that 55 cases of high-position small intestinal fistula, except for 1 case of Crohn's disease complicated with intestinal fistula, all occurred postoperatively. The causes of postoperative intestinal fistula are diverse.

　　1. Gastrointestinal anastomotic leak:It is a common cause of intestinal fistula. Many anastomotic leaks are due to shortcomings in operation techniques. For example, the diameter of the gastrointestinal tract at both ends of the anastomosis is too different, the alignment is not uniform during anastomosis, causing a larger gap in one place; the anastomosis is too dense or too loose; the blood supply of the anastomosis is insufficient or the tension is too high; the intestinal wall at the anastomosis site is edematous, scarred, or infiltrated by cancer, etc. In addition, postoperative obstruction of the distal intestinal tract or poor decompression of the proximal gastrointestinal tract can also be a cause of anastomotic fistula.

　　2. Duodenal fistula:Due to only part of the peritoneum covering, the duodenum is prone to fistula after anastomosis or suture. According to the location of the fistula, it can be divided into end fistula and lateral fistula, among which the lateral fistula that loses intestinal fluid is more serious and has a poorer prognosis. End fistula mostly occurs after gastric resection, or due to scar tissue at the residual end, or due to insufficient blood supply, or due to improper suture operation, such as excessive inversion or high tension. A large number of lateral fistulas are caused by incision and shaping of the duodenal ampulla, or due to omissions during incision and suture, causing a leak in the posterior wall of the duodenum, or due to excessive tension of the transverse suture after longitudinal incision of the anterior wall of the duodenum; it can also occur during right nephrectomy or right colon surgery when the duodenum is accidentally injured.

　　3. Surgical injury:During abdominal surgery, if the exposure is not good or there is extensive intestinal adhesion, or if the surgeon's experience is insufficient and the actions are rough, the intestinal wall or its blood supply may be damaged, causing an intestinal fistula. Among them, extensive intestinal adhesion surgery is most susceptible to intestinal wall injury, which requires special attention.

　　4. After surgery, the retained gauze and other foreign bodies or the improper placement of drainage tubes, steel wire sutures, etc.:Most of the gauze left in the abdominal cavity after surgery causes intestinal perforation and abdominal abscess, the abscess may perforate the incision spontaneously, or form an external fistula after surgical drainage. Improper placement of drainage tubes after abdominal surgery (tubes too hard, catheters pressing tightly against the intestinal wall) can compress and wear the intestinal wall, causing an external fistula. When blind puncture incisions are placed on the abdominal wall after surgery, care should be taken to be gentle to avoid injury. In addition, negative pressure aspiration of the abdominal cavity drainage tube may adhere to the intestinal wall, causing ischemic necrosis and perforation of the intestinal wall, which should be avoided. If it is necessary to maintain continuous negative pressure aspiration, double-lumen tubes should be used for drainage. To reduce tension, the best place for钢丝suture wire is outside the peritoneum, otherwise, when the intestine is overdistended, the wire can press on the intestinal wall and cause an intestinal fistula.

　　Two, traumatic abdominal sharp or blunt trauma can cause injury to the intestinal tract and form an intestinal fistula.Especially the part of the duodenum posterior to the peritoneum, due to fixation, is susceptible to compression injuries. Perforation of the intestine usually enters the free peritoneal cavity, causing diffuse peritonitis; perforation of the posterior wall forms a retroperitoneal abscess, which can later break into the free peritoneal cavity.

　　There are reports of intestinal fistula caused by acupuncture treatment. Radiotherapy may also damage the intestinal wall and cause fistula.

　　Three, diseases causing small intestinal fistula: After the perforation of acute appendicitis, a surrounding abscess often forms, and after drainage, an appendiceal stump fistula often forms.Inflammatory bowel diseases such as Crohn's disease, intestinal tuberculosis, and intestinal tumors can all cause intestinal perforation and fistula. Crohn's disease and other inflammatory diseases such as peritonitis can also cause internal fistulas between different intestinal segments. Another common type of fistula is the fistula between the gallbladder or bile duct and the intestinal segment. When the gallbladder becomes adherent to the duodenum due to inflammation, the gallstones in the gallbladder can compress the adherent site, causing ischemia and necrosis, and then become a fistula (gallbladder- duodenal fistula). The gallbladder fistula can also lead into the stomach or colon. Duodenal ulcer can also be complicated with gallbladder or bile duct- duodenal fistula. After acute necrotizing pancreatitis develops abscesses, it can also rupture into the intestinal tract and form a fistula.

　　Four, congenital atresia of the vitelline duct can cause congenital umbilical intestinal fistula.

　　The pathophysiology caused by small intestinal fistulas can vary depending on the height of the fistula. Generally speaking, the physiological disturbance caused by high intestinal fistulas is more serious than that of low fistulas. The following pathophysiological changes are roughly as follows.

　　1, Disturbance of water and electrolyte balance, acid-base balance: The estimated amount of gastrointestinal secretions in adults is 7000-10,000ml per day, most of which are reabsorbed in the proximal ileum and colon. Therefore, the upper small intestinal fistulas in the duodenum and proximal jejunum lose a large amount of intestinal fluid each day, up to 7000ml. Therefore, if timely supplementation is not provided, dehydration, hypovolemia, peripheral circulatory failure, and shock can occur quickly.

　　At the same time as the loss of a large amount of water, there is also a loss of electrolytes, which varies depending on the location of the fistula. If the main loss is gastric juice, the loss of electrolytes is mainly H+ and Cl; if the loss is intestinal fluid, it is mainly Na+, K+, and HCO3. Generally, small intestinal fistulas can lose 2-40g of NaCl per day. With the loss of electrolytes, it necessarily affects the acid-base balance, and the loss of a large amount of alkaline intestinal fluid often causes metabolic acidosis, while the loss of acidic gastric juice can cause hypokalemic alkalosis.

　　The loss of water and electrolytes in low intestinal fistulas is less, such as the daily fluid loss from the distal ileum fistula is only about 200ml, rarely causing serious physiological disturbances.

　　An internal fistula between the upper small intestine and the colon short-circuits a long segment of the intestine with important digestive and absorptive functions, which can cause severe diarrhea, and can also lead to severe electrolyte imbalance and malnutrition.

　　2, Infection: A small number of intestinal fistulas are formed due to the non-healing of surgical drainage sites, such as the non-healing of the duodenal or jejunal stoma; others are formed by gradually穿透 between two adherent hollow organs; these fistulas are not accompanied by significant local or systemic infection during the formation process. However, most intestinal fistulas are complicated by localized or diffuse peritonitis, abscesses, single or multiple. Patients may have fever, abdominal pain, distension, gastrointestinal dysfunction such as nausea, vomiting, anorexia, diarrhea, or no defecation and flatus, weight loss, toxic symptoms, and even sepsis, shock, and death; complications such as stress ulcers, gastrointestinal bleeding, toxic hepatitis, ARDS, renal failure, and others may also occur.

　　3. Malnutrition With the loss of intestinal fluid, there is also a large loss of digestive enzymes and proteins, and the digestive and absorptive function is damaged, causing negative nitrogen balance, vitamin deficiency, rapid weight loss in the patient, anemia, hypoproteinemia, and even cachexia and death.

　　4. The skin around the fistula is eroded due to long-term erosion by digestive juices, and the skin around the fistula is prone to erosion, with the patient reporting severe pain. Especially for high intestinal fistula, the intestinal fluid contains a rich amount of digestive enzymes, which is more likely to cause skin damage. The granulation tissue next to the abdominal fistula can also be corroded by digestive juices and bleeding.

　　Small bowel fistula loses a large amount of intestinal fluid every day. If it is not supplemented in time, it can quickly cause complications such as dehydration, hypovolemia, peripheral circulatory failure, and shock.

　　Small bowel fistula can cause gastrointestinal dysfunction, leading to diarrhea or no defecation or flatus, weight loss, toxic symptoms, and even septicemia, shock, and death. It may also develop complications such as stress ulcers, gastrointestinal bleeding, toxic hepatitis, ARDS, renal failure, and others.

　　The clinical manifestations of small bowel fistula vary due to different locations and causes, and also vary at different stages of fistula formation.

　　Generally, within 2 to 7 days after gastrointestinal surgery, the patient reports discomfort, abdominal distension, the gastrointestinal function has not recovered, the body temperature remains above 38℃, the pulse rate is more than 100 times per minute, the white blood cell count increases, manifested as nausea, vomiting, no anal defecation or flatus, or an increase in the frequency of defecation but a small amount, watery stools, and still feeling abdominal discomfort after defecation. Abdominal signs present abdominal infection, peritonitis, intestinal paralysis, redness and swelling of the abdominal incision, which is a typical incision infection. When the incision breaks through, purulent bloody fluid can be discharged, and a large amount of fluid, namely intestinal fluid, is discharged 24 to 48 hours later. After drainage, the symptoms such as fever and increased white blood cell count can improve.

　　The loss of a large amount of intestinal fluid can cause serious water and electrolyte imbalance, even hypovolemic shock, the patient cannot eat, and nutritional supplementation is also difficult, which leads to rapid weight loss and emaciation, manifested as malnutrition. The patient may also develop sepsis and/or septicemia, leading to multiple organ failure and death. If the drainage is smooth and the infection is controlled, the general condition improves, and nutritional supplementation is timely and effective, the fistula can close spontaneously.

　　Additionally, due to the large amount of intestinal fluid flowing out of the fistula, the skin around the fistula often becomes red, eroded, and shows eczema-like changes.

　　The amount of drainage volume is of great value for estimating the position of the fistula, generally speaking, the higher the small intestine fistula, the more the drainage volume and the thinner the quality, containing bile and pancreatic juice, while the lower the small intestine fistula, the less the drainage material and the thicker the quality, the drainage fluid from the incision fascia is relatively clear, which often occurs 2 to 5 days after surgery, therefore, the occurrence time helps to differentiate between incision fascia rupture and early intestinal tract rupture.

　　After abdominal trauma or surgery, if the following conditions occur, it should be considered that there is a possibility of intestinal fistula:

　　1. There is a continuous large amount of exudate from the abdominal incision or wound and (or) drainage tube.

　　2. Bile-like fluid appears from the incision or drainage tube, gas is excreted, or faeces-like fluid is drained out.

　　3. The appearance of persistent diaphragmatic irritation (such as hiccups), pelvic irritation (such as urgent need to defecate), or signs of peritonitis after surgery.

　　4. The appearance of persistent fever and abdominal pain due to unknown reasons after surgery.

　　It should be pointed out that when abdominal膜炎 symptoms and signs appear after surgery, the possibility of fistula should be considered. The reaction of patients after abdominal surgery to abdominal infection is different from that of normal people. The reactions such as abdominal pain and abdominal muscle contraction are significantly weakened. Therefore, when facing a patient with a persistent body temperature above 38℃ and a heart rate of ≥100 beats per minute, with only abdominal distension but no obvious abdominal pain, no abdominal muscle rigidity, one should be vigilant about the possibility of peritonitis. At this time, B-ultrasound, abdominal X-ray film, and diagnostic peritoneal puncture often have positive findings. If necessary, re-examination can be repeated. If it is not possible to complete the diagnosis immediately after the external fistula is formed, the diagnosis is not difficult. However, to confirm the diagnosis and further understand the pathophysiology, the following examinations can be performed.

　　1. Oral dye test: It is the simplest and most practical method. Dye such as methylene blue, bone charcoal powder, Congo red, or indigo carmine is given to the patient orally, and it is observed whether the dye is excreted from the fistula orifice. The time of dye excretion can be used to guess the location of the fistula, and the amount of dye excreted can also be used as a factor to guess the size of the fistula orifice.

　　1. Fistula造影: It is a more reliable and direct examination method. A thin plastic catheter is inserted from the fistula orifice, and a metal object is used as a marker at the fistula orifice. Contrast agents such as diatrizoate, 12.5% sodium iodide, or iodine oil are injected into the catheter. At the same time, the movement of the contrast agent is observed on the fluorescent screen. At this time, the depth of the catheter insertion, the amount of contrast agent injection, and the patient's position can be adjusted. Photos can be taken at an appropriate time, and photos can be repeated after a few minutes. This can help understand the length of the fistula, which segment of the intestine it leads to, and whether there is an abscess present.

　　2. Gastrointestinal barium meal造影: It can also show the location of the fistula, but due to the thicker consistency of barium than water-soluble contrast agents, it is difficult to completely display the entire fistula and abscess. However, it can observe whether there is obstruction of the distal part of the intestine. On the other hand, since the internal fistula of the small intestine cannot undergo the aforementioned fistula contrast examination, gastrointestinal barium meal examination becomes the main diagnostic examination measure. If there is a suspicion of colonic fistula, barium enema examination can also be performed. If it is an internal fistula between the biliary tract and the intestinal tract, an abdominal X-ray film can show gas shadowing in the bile duct. During the barium meal, the barium can be seen to pass through the gastrointestinal fistula orifice into the gallbladder or bile duct, thus confirming the diagnosis.

　　The clinical manifestations of small bowel fistulas vary due to different locations and causes, and the different stages of fistula formation also have different manifestations. Here, we take the most common abdominal postoperative small bowel fistula as an example for introduction.

　　To exclude the diagnosis of fistula, fasting can be initially implemented, and gastroenteric decompression can be performed.

　　Most small bowel fistulas occur during abdominal surgery, and their main causes include the body's internal environment, nutritional status, and immune function. In addition to the urgency of emergency surgery, adequate preoperative preparation should be made for elective surgery, correcting electrolyte imbalance, improving nutrition, controlling infection, which will effectively reduce the occurrence of fistulas.

　　For extensive abdominal adhesion surgery, the operation should be patient and meticulous, reducing the injury to the intestinal wall. Small tears in the seromuscular layer should be repaired, and for larger injuries that do not involve a longer segment of the intestine, it may be considered to resect the adherent intestinal segment. The indications for surgery in inflammatory intestinal obstruction should be strictly controlled.

　　Fistula rupture at the anastomosis is one of the main causes of intestinal fistula formation. There are many reasons for fistula rupture causing intestinal fistula, and anastomotic technique is the key. Overly dense suturing can lead to local tissue ischemia and poor healing, while too loose suturing can cause leakage at the anastomotic site. Effective gastrointestinal decompression after surgery is an effective measure to prevent anastomotic fistula, and controlling abdominal infection is an essential factor to ensure good healing. Necessary abdominal drainage is also important.

　　Oral dye test is the simplest and most practical method for checking small intestinal fistula. The patient is given an unabsorbable dye, such as methylene blue, bone charcoal powder, Congo red, or indigo carmine, and it is observed whether the dye is excreted from the fistula. The time of dye excretion can also be used to guess the location of the fistula, and the amount of dye excreted can also be used as a factor to guess the size of the fistula opening.

　　Fistulography is a more reliable and direct examination method. A thin plastic catheter is inserted from the fistula, and a metal object is used as a marker at the fistula. Contrast agents such as Gastrografin, 12.5% sodium iodide, or iodine oil are injected into the catheter, and the movement of the contrast agent is observed on the fluorescent screen. At this time, the depth of insertion of the catheter, the amount of contrast agent injected, and the patient's position can be adjusted, and the appropriate time for photography can be selected. Repeated photography can be performed a few minutes later, and based on this, the length of the fistula, which segment of the intestine it leads to, and whether there is an abscess can be understood.

　　Gastrointestinal barium enema can also show the location of the intestinal fistula, but since barium is thicker than water-soluble contrast agents, it is difficult to completely display the entire fistula and abscess. However, it can observe whether there is a distant intestinal obstruction, and on the other hand, small intestinal fistulas cannot be examined by the aforementioned fistula contrast examination, so gastrointestinal barium meal examination becomes the main diagnostic measure. If a colonic fistula is suspected, barium enema examination can also be performed. If it is an internal fistula between the biliary system and the intestinal tract, the abdominal plain film can show gas shadowing in the bile duct, and during the barium meal, barium can be seen passing through the gastrointestinal fistula opening into the gallbladder or bile duct, thus confirming the diagnosis.

　　CT and ultrasound examinations are beneficial for the localization diagnosis of abdominal abscesses. When the abscesses in the hidden areas between the intestinal loops are affected by the gas in the intestinal cavity, abdominal CT examination helps in diagnosis.

　　Many foods can have unexpected harmful effects on our intestines, especially for patients with intestinal fistula. Therefore, we should pay more attention to our diet in daily life to avoid negative health effects caused by an imbalance.

　　1. Meat:There is no fiber-rich fiber. If the meat is not fully chewed, it is difficult to digest, leading to the proliferation of bacteria in the intestines. Statistics show that in meat-consuming countries, the incidence of colon cancer is constantly rising.

　　2. Saturated fats:Saturated fats refer to animal fats and artificial fat cream. The accumulation of saturated fats alters the intestinal flora, increasing the content of bacteria that promote the conversion of bile salts into carcinogenic substances.

　　3. Gluten:Gluten will form a paste-like sticky substance, adhering to the inner wall of the intestines. It delays the passage of food, easily causes intestinal putrefaction, and hinders the absorption of vitamin B group.

　　4. Sugar:It is conducive to the rapid reproduction of bacteria in the intestines, especially Escherichia coli, which is easy to form oxalate, which is a cause of rheumatism.

　　5. Refined flour:It is easy to make the stool hard, especially when there is a lack of fruits and vegetables in the food structure, the situation of the consumer will become more serious.

　　The treatment of small bowel fistula in Western medicine first requires solving the primary pathological change, such as Crohn's disease of the intestine or other intra-abdominal inflammatory lesions. The acute lesion of the primary disease should be controlled first, and then surgical treatment should be performed. Simple fistula repair surgery can be performed, such as the cholecystoduodenal fistula, after separating the adhesions between the two, the scar tissue around the duodenal fistula opening can be excised, and the incision can be sutured transversely. Then, the diseased gallbladder can be excised. If there is scar stenosis, tumor, or severe inflammation at the site of the internal fistula, it is advisable to excise the diseased intestinal segment for end-to-end anastomosis.

　　The treatment of small bowel fistula varies with the disease stage. The following is described in three stages, but it should be noted that the division of time below is only approximate and can be changed according to different patients.

　　First, in the early stage The peritonitis stage is generally within 2-4 weeks after onset. The key to treatment is to drain smoothly and early, control infection, correct hypovolemia and electrolyte disturbance, and pay attention to protect the skin around the fistula opening.

　　1. Detect abdominal abscess and perform thorough drainage: After diagnosing peritonitis or abdominal abscess, short-term preparation can be made and early laparotomy and drainage can be performed. Absorb all pus, find the fistula opening, flush the abdominal cavity, and then place double-lumen tubes for drainage. Pay attention to the possibility of multiple abscesses and do not miss any. The drainage tube should be placed at the lowest position near the fistula opening. It is best to fix another thin plastic tube on the double-lumen tube for flushing, which can continuously flush the abscess cavity and drainage tube with sterile water containing antibiotics to ensure good drainage.

　　2. Correct hypovolemia and electrolyte disturbance: Many intestinal fistula patients have severe loss of intravascular and interstitial fluid. Therefore, before laparoscopic drainage, it is necessary to first correct hypovolemia and supplement adequate isotonic fluid. At the same time, place gastrointestinal decompression to keep the gastrointestinal tract in a functional static state, reduce secretion, and decrease the amount of loss. The fluid volume and composition after drainage surgery can be adjusted according to the intestinal fistula drainage volume and gastrointestinal decompression volume, urine output, skin elasticity, etc., and electrolytes and blood gas analysis can also be measured to understand the degree of disturbance in electrolyte and acid-base balance. Central venous pressure can also be measured if necessary. Generally, it can be completely corrected in the first few days of treatment, and then supplemented according to the loss to maintain homeostasis.

　　3. Use antibiotics to control the spread of infection: A broad-spectrum antibiotic and an aminoglycoside drug can be used, and metronidazole can be added if anaerobic bacteria are suspected. It must be emphasized that antibiotics cannot replace surgical drainage but can only be used as an auxiliary measure during surgical treatment. If infection and intoxication symptoms continue after the above treatment, it suggests that there may still be an abdominal abscess, and repeated X-rays and B-ultrasound examinations are required, and CT examination is necessary if necessary to find and treat the abscess.

　　4. Control intestinal fistula, prevent skin erosion: Small bowel fistulas, especially high bowel fistulas, due to the large amount of digestive enzymes, are extremely prone to cause skin erosion, causing great pain to the patients and affecting the surgical treatment of the fistula. Different collection methods of fistula fluid should be designed for different patients. In addition to the most commonly used double lumen catheter negative pressure continuous aspiration method, patients can also be placed on a separate quilt in a prone position, allowing the fistula to be in the lowest position of the body. Record the amount of drainage fluid daily to understand the development of the fistula and decide the amount of fluid replacement accordingly. The skin around the fistula opening must be coated with zinc oxide ointment, Karaya gum, etc. to prevent skin erosion.

　　Second, middle period It is generally the second or third month after the illness. Intra-abdominal infection has been basically controlled, and the external fistula has formed. During this period, in addition to continuing to pay attention to maintaining good drainage and controlling infection, it is also important to continue to protect the skin around the fistula. More importantly, supplementing nutrition, strengthening the body, and striving for the spontaneous closure of the fistula.

　　The causes of death in intestinal fistula patients, in addition to uncontrolled infection and the occurrence of sepsis, are also important due to malnutrition, weight loss, anemia, and hypoproteinemia. This is due to the excessive loss from the fistula and insufficient calorie intake. Many authors emphasize the importance of improving nutrition in the treatment of intestinal fistulas. The General Hospital of the Nanjing Military Region reported that 33.8% of patients with serum albumin below 2.5g/dl died, while only 16% of those with serum albumin above 2.5g/dl died.

　　There are many methods to supplement nutrition, and they should be selected according to specific circumstances:

　　1. Parenteral nutrition: It is not advisable to eat through the mouth in the early stages of intestinal fistula, as food can stimulate the secretion of digestive juices in the intestines, increasing the loss of intestinal fluid and exacerbating malnutrition. Therefore, it is necessary to place gastrojejunal decompression in the early stage of intestinal fistula to allow the gastrointestinal tract to rest. Parenteral nutrition can be initiated after correcting water and electrolyte imbalances. Only by controlling infection can parenteral nutrition completely ensure that patients achieve a positive nitrogen balance and maintain a satisfactory nutritional status. If necessary, parenteral nutrition can be continued throughout the entire treatment process of the intestinal fistula. Intestinal fistula patients require more than 3000 calories per day, and peripheral venous fluid infusion is difficult to meet this requirement, and a catheter needs to be inserted into the central vein. Long-term insertion of catheters in large veins should pay attention to preventing catheter infections. For specific methods of parenteral nutrition, refer to Chapter 4 Surgical Metabolism and Nutrition.

　　2. Feeding through the duct or mouth: In the long run, nutrition administered through the digestive tract is superior to intravenous nutrition, as a large part of the intestinal mucosal metabolism relies on nutrients in the intestinal lumen. The method varies according to the location of the fistula. High fistulas can be fed through a tube inserted into the lower part of the fistula, infused with high-calorie, high-protein liquid food or mixed milk, or an enterostomy can be made at the distal end of the fistula to infuse nutrition. Low fistulas, such as distal ileal or colonic fistulas, can be fed with normal or elemental diets through the mouth. Nutritional supplementation for mid-segment intestinal fistulas is more difficult, and often the effect of elemental diets is better in addition to intravenous nutrition. Elemental diets contain most nutrients in the form of simple molecules, including oligopeptide amino acids, triglycerides, fatty acids, oligosaccharides, etc., and inorganic substances and vitamins are added as needed.

　　Through the above treatment, about 40% to 70% of the fistulas can heal spontaneously.

　　Third, the late stage After 3 months of the occurrence of the intestinal fistula. At this time, the nutrition maintenance is satisfactory, the gastrointestinal function has been restored, and if the fistula has not healed, surgical treatment can be performed.

　　Before surgery, a simpler occlusion therapy can be tried: The distal part of the fistula should be free of obstruction, without local tumor, abscess or foreign body. When the fistula orifice is not large and the fistula tract has not been epithelialized, various simple methods of occluding the fistula orifice can be used, such as filling with oil gauze, medical glue filling, rubber sheet blocking, etc. If it is still ineffective, surgical treatment can be performed.

　　1. Simple fistula repair: It is suitable for fistula with small orifice and basically controlled surrounding infection. The surrounding scar should be excised before suture, otherwise it is easy to fail. Most small internal fistulas are suitable for repair. Some early leakage after surgery can also try repair, but the failure rate is high. In recent years, using intestinal segment serosal film to cover and repair the repair area can improve the success rate of repair.

　　2. Fistula segment excision and anastomosis: It is the most commonly used method in the surgical treatment of fistula and also the most effective method.

　　3. Fistula bypass surgery: It is suitable for the situation where the intestinal loops around the fistula are adhered into a mass and difficult to separate. After separating the proximal and distal intestinal segments outside the adherent mass and cutting them, the proximal and distal free intestinal segments are anastomosed to restore the intestinal passage. The two ends of the adherent mass or sutured or made into a peritoneal wall stoma, and the secondary operation to remove the adherent intestinal mass is performed after the fistula heals.

　　Prognosis

　　The mortality rate of external fistula of small intestine is 10% to 20%, and factors such as the age of the patient, the etiology of the external fistula, peritoneal infection, the location and number of the fistula, and the amount of intestinal fluid drainage are factors affecting its prognosis. If the mortality rate of external fistula of small intestine in people over 70 years old reaches 62%; the mortality rate of high-flow fistula exceeds 20%; the mortality rate of multiple fistula is higher than that of single fistula; the mortality rate of fistula in normal intestinal segment is less than 20%, while that in case intestinal segment can reach 48%, radiation enteritis reaches 77%, and neoplastic intestinal segment is 54%; the risk of fistula caused by emergency surgery is 3 to 4 times higher than that of elective surgery; the mortality rate of fistula with peritoneal infection is high.