What Is an Intestinal Fistula?

Intestinal fistula refers to abnormal passages in the intestine and other organs, or intestines and abdominal cavity, outside the abdominal wall. The former is called internal fistula, and the latter is external fistula. Intestinal fistula causes intestinal contents to flow out of the intestinal lumen, causing a series of pathophysiological changes such as infection, fluid loss, malnutrition, and organ dysfunction.

Basic Information

Visiting department: Anorectal, General Surgery
Common locations: intestinal
Common causes: Surgery, trauma, abdominal infections, malignancy, radiation injury, chemotherapy, and intestinal inflammation and infectious diseases

Common symptoms: Intestinal contents flow out of the intestinal lumen
Contagious: no

Causes of intestinal fistula

Common causes of intestinal fistula include surgery, trauma, abdominal infection, malignancy, radiation injury, chemotherapy, and intestinal inflammation and infectious diseases. Clinically, parenteral fistula mainly occurs after abdominal surgery, which is a serious complication after surgery. The main cause is postoperative abdominal infection, anastomosis, and intestinal canal blood flow. Intestinal inflammation, tuberculosis, intestinal diverticulitis, malignant tumors and trauma infections, abdominal inflammation, and abscesses can also directly penetrate the intestinal wall and cause intestinal fistula. Some are complications of inflammatory bowel disease itself, such as internal or external fistula caused by Crohn's disease. According to the analysis of clinical data, intestinal fistula is most common secondary to abdominal abscess, infection and post-operative intestinal fistula. Intestinal fistula is common in malignant tumors. Radiation therapy and chemotherapy can also cause intestinal fistulas, which are relatively rare.

Clinical manifestations of intestinal fistula

Fistula

There are one or more fistulas in the abdominal wall, and intestinal fluid, bile, gas, or food are discharged, which is the main clinical manifestation of extraintestinal fistula. Postoperative parenteral fistula may develop symptoms 3 to 5 days after the operation, first with abdominal pain, bloating and elevated body temperature, followed by local or diffuse signs of peritonitis or intraabdominal abscess. About 1 week after the operation, the abscess was punctured to the incision or drainage port, and pus, digestive fluid, and gas could be seen in the wound. Smaller parenteral fistulas can only manifest as persistent, infectious sinus tracts, with intestinal contents or gas being intermittently expelled at the sinus tract. Severe parenteral fistula can be observed directly on the wound with ruptured bowel and eversion of the intestinal mucosa, that is, the labial fistula; or although the bowel can not be seen directly, a large amount of intestinal contents flow out, which is called a tubular fistula. Due to the digestion and erosion of tissues from the fistula, and the presence of infection, it can cause skin erosion or bleeding in the fistula.

2. Nutrient absorption disorders

After the occurrence of parenteral fistula, due to the loss of a large amount of digestive fluid, patients may have obvious water, electrolyte disorders and acid-base metabolism imbalance. Because the body is under stress, catabolism is strengthened, and negative nitrogen balance and hypoproteinemia can occur. In the elderly with severe disease, due to the absorption of nutrients and the loss of a large amount of nitrogenous substances from the fistula, the patient's weight can be significantly reduced, subcutaneous fat disappeared, or skeletal muscle atrophy.

3. infection

During the development of extraintestinal fistulas, intestinal intercondylar abscesses, subcondylar abscesses, or abscesses around the fistula may appear.Because these infections are often hidden, and their fever, increased white blood cell count, and abdominal pain are often caused by the original disease or surgery Trauma, etc. is masked, so it is difficult to make a diagnosis and effective drainage early.

Bowel fistula examination

Plain abdominal film

Find out whether there is intestinal obstruction and whether there is abdominal space occupying disease by standing abdominal and lying plain film examination. B ultrasound can check the abscess and its distribution in the abdominal cavity, understand the presence of pleural and ascites, and the presence of lesions of the parenchymal organs. Percutaneous puncture and drainage under the guidance of B ultrasound may be performed if necessary.

2. Gastrointestinal angiography

Including oral contrast agent for total gastrointestinal angiography and abdominal wall fistula for gastrointestinal angiography, is an effective means to diagnose intestinal fistula. It is often clear whether there is an intestinal fistula, the location and number of intestinal fistulas, the size of the fistula, the distance between the fistula and the skin, whether the fistula is accompanied by the pus cavity and the drainage of the fistula. Whether the intestinal canal is unobstructed. If it is a labial fistula, after the condition of the proximal intestine of the fistula is clarified, a contrast agent can be injected into the distal intestine through the fistula for examination. For gastrointestinal angiography in patients with intestinal fistula, attention should be paid to the choice of contrast agent. Barium is generally not suitable, because it cannot be absorbed and is difficult to dissolve, and it will cause the barium to remain in the abdominal cavity and fistula, forming foreign bodies and affecting the self-healing of intestinal fistula; inflammatory reactions caused by barium leaking into the abdominal cavity or chest cavity Also more intense. In general, patients with early parenteral fistula use 60% diatrizoate more frequently. 60% to 100ml of diatrizoate is administered orally or through a gastric tube, which can clearly show the condition of intestinal fistula, intestinal cavity and leakage into the abdominal cavity. The ubiquitamine glucosamine is quickly absorbed. It is not necessary to further dilute 60% bisglucamine, otherwise the contrast of the contrast is poor, and it is difficult to determine the intestinal fistula and its accompanying conditions. Gastrointestinal peristalsis and contrast agent distribution should be observed dynamically during angiography. Pay attention to the location of leakage of contrast agent, the amount and speed of leakage, and the presence of branch forks and pus cavities.

3.CT

It is an ideal method for clinical diagnosis of intestinal fistula and its concurrent abdominal and pelvic abscess. In particular, CT scans of oral gastrointestinal contrast agents can not only clarify the intestinal patency and fistula, but also assist in preoperative evaluation and help determine the timing of surgery. Intestinal CT examination with obvious inflammatory adhesions showed intestinal adhesions forming clumps, thickening of the intestinal wall and intestinal effusion. At this time, if extensive adhesion separation is performed in the surgery, not only the adhesion can not be completely separated, but also secondary intestinal damage will be caused, more fistulas will be generated, and the operation will completely fail. Other examinations: Small intestine gall bladder fistula, small intestine bladder fistula, etc. should be checked for bile duct and urography.

Intestinal fistula diagnosis

1. Pay attention to the cause

Note whether there are traumatic factors such as abdominal trauma, surgery, or pathological causes such as acute appendicitis, intestinal obstruction, duodenal ulcer perforation, tumors, intestinal tuberculosis, clonal disease, and ulcerative colitis. Should inquire about the medical history, the occurrence of intestinal fistula and treatment.

2. Clarify the location of intestinal fistula and fistula

(1) If fistula is suspected early, but no clear intestinal fluid or gas has overflowed from the wound, dye or bone charcoal powder can be taken orally to observe whether the secretions of the fistula are stained. Positive results confirm the diagnosis of intestinal fistula, but negative results cannot rule out the presence of intestinal fistula.

(2) Align the fistula with a syringe or a wound device (without a catheter to insert the fistula), directly inject 15% to 20% water-soluble iodine contrast agent 40 to 60ml for fistula imaging, observe the fistula path, and whether there is pus cavity near the fistula And the site of the intestinal wall fistula.

(3) According to the possible parts of the intestinal wall fistula, check the barium meal or barium enema of the gastrointestinal tract, and observe the condition of the fistula and its proximal and distal intestines.

(4) For patients with suspected abdominal abscess, abdominal ultrasound and CT should be performed.

(5) For pathological intestinal fistula, fistula tissue should be excised and sent for pathological examination.

3. check

(1) Collect the intestinal fluid and urine that flow out of the fasting for 24 hours, and measure the amount and electrolyte content, respectively.

(2) Take the secretions from the fistula and pus cavity for bacterial culture (anaerobic and aerobic bacteria), if necessary, draw blood for culture and perform bacterial drug sensitivity tests.

(3) Blood test: blood bilirubin, albumin / globulin, glucose, electrolytes (blood potassium, sodium, chlorine, calcium, magnesium, phosphorus, etc.) and blood urea nitrogen, creatinine, carbon dioxide binding capacity.

(4) Arterial blood is drawn for blood gas analysis.

(5) In severe abdominal infections, there are often multiple organ dysfunctions. In addition to the above examinations, chest radiographs and ECG examinations are performed when necessary.

Differential diagnosis of intestinal fistula

Gastrointestinal perforation

Sudden abdomen pain can be abrupt. Abdominal fluoroscopy can reveal free gas under the diaphragm, with signs of peritonitis. Intestinal inflammatory diseases include bacterial dysentery, ulcerative colitis, Crohn's disease, etc. These diseases can appear abdominal pain, diarrhea, mucus and bloody stools, and colonoscopy can be identified. It is similar to the age of colon cancer. It may coexist, and clinical manifestations partially overlap. Complications such as intestinal obstruction, bleeding, perforation, and fistula formation can occur. Barium enema is helpful for identification, irregular mucosa, and intestinal filling defect are radiological signs of colon cancer. Colonoscopy and mucosal biopsy have diagnostic significance for colon cancer.

2. Crohn's disease of the colon

Colonic Crohn's disease is characterized by abdominal pain, fever, elevated peripheral white blood cell counts, abdominal tenderness, and abdominal masses. Fistula formation is its characteristic. These symptoms and signs are similar to diverticulitis. Endoscopy and X-ray examination can find paving stone-like mucosa, deep ulcers, and lesions with a "jump" -like distribution to help identify. Endoscopic mucosal biopsy has diagnostic value if non-caseinous granulomas are found. Ulcerative colitis can be manifested as fever, abdominal pain, bloody stools, and increased peripheral white blood cell counts. Colonoscopy shows diffuse inflammation, hyperemia, and edema of the mucosa. With the development of the disease, erosions, ulcers, pseudopolyps, and residual mucosal atrophy between ulcers may appear. In the later stage, the bowel cavity narrows and the colonic bag disappears. On examination, changes in goblet cells and crypt abscesses were seen. Ischemic colitis occurs in the elderly and can occur concurrently with colonic diverticulosis. Clinical manifestations are mostly black stools after severe abdominal pain. Barium enema examination can be used to diagnose ischemic colitis with characteristic thumb pattern signs. Colonoscopy can help diagnose the disease.

Intestinal fistula treatment

Control infection

(1) In the early stage of fistula, if the drainage is not smooth, when performing a laparotomy, a large amount of physiological saline is used to flush the abdominal cavity and multiple drainages are performed;

(2) The intestinal fistula or abdominal abscess was drained with double cannula for 24 hours.

(3) During the treatment, observe closely the formation of new abdominal abscesses and deal with them in time.

2. Fistula management

(1) In the early days, double cannulas were mainly used for continuous negative pressure drainage, and the leaked intestinal fluid was drained to the outside as far as possible. After about 1 to 4 weeks of drainage, a complete fistula can be formed, and the intestinal fluid no longer overflows into the abdominal cavity outside the fistula. After continuous negative pressure drainage, if there is no factor that prevents the fistula from healing, the tubular fistula will usually heal within 3 to 6 weeks. Total parenteral nutrition can reduce the amount of intestinal fluid secretion. If somatostatin is added, the amount of intestinal fluid leakage can be reduced, the self-healing rate of the tubular fistula and the healing time can be shortened.

(2) After infection control and fistula formation, tubeless fistula can be blocked with medical adhesive to prevent intestinal fluid leakage and promote healing of fistula when it is confirmed by angiography that there is no pus cavity and no obstruction in the distal intestine.

(3) A labial fistula or a tubular fistula with a large fistula and a short fistula can be blocked internally with a silicone sheet to mechanically close the fistula and maintain the continuity of the intestine, control the leakage of intestinal fluid, and restore intestinal function. To achieve the purpose of simplified processing and strengthen intestinal nutritional support. If the distal bowel obstruction is obstructed, "internal blockage" cannot be used, and continuous negative pressure drainage should still be performed.

(4) In the case of good drainage of the intestinal fluid, the fistula is not very large, and the skin around the fistula is not eroded. An artificial anal bag can be used to protect the skin and prevent skin erosion and reduce the number of dressing changes. The patient's activities are convenient. If the skin is erosive, change the dressing 1 or 2 times a day, and generally do not need to apply ointment protection. If necessary, apply compound zinc oxide ointment.

3. Nutritional support

(1) Total parenteral nutrition can be applied early after fistula development or when intestinal function is not restored. If you need to use total parenteral nutrition for a long time, you should supplement glutamine.

(2) When the function of the small intestine distal or proximal to the fistula is more than 150cm, the nasogastric tube (for low intestinal fistula, colon fistula, etc.), jejunostomy cannula, or fistula cannula (for Duodenal fistula, gastrointestinal anastomotic fistula, esophageal jejunal anastomotic fistula, etc.) perfusion factor diet.

(3) After the fistula is "internally blocked", the oral diet can be resumed.

(4) Regardless of the nutritional support method applied, proper heat energy and protein supply quality are required to achieve a positive nitrogen balance.

4. Surgery

(1) Indications for surgery Unhealed tubular fistula: Factors affecting tube fistula healing include tuberculosis, tumor, distal intestinal obstruction, foreign body retention, residual abscess near fistula, scarring or epithelialization of fistula, etc .; Fistula: Rarely can heal itself.

(2) The timing of surgery Deterministic bowel fistula surgery should be performed when the infection has been controlled and the patient's general condition is good, usually 3 months or more after the fistula occurs. Due to factors such as inflammation, infection, and malnutrition, the success rate of early surgery is not high.

(3) Surgical methods The surgical methods of intestinal fistula include local intestinal loop wedge resection and suture of fistula, intestinal segment resection and anastomosis, intestinal loop fistula intestinal fistula, and repair of vascularized intestinal seromuscular sheet or full-thickness intestinal sheet repair. Surgery. Among them, intestinal segment resection and anastomosis is the most commonly used, and intestinal myometrial slices are used to repair fistulas that are difficult to remove.

(4) After the operation , the abdominal cavity is flushed with a large amount of isotonic saline (more than 6000ml), and a double cannula is placed for negative pressure drainage to prevent the occurrence of abdominal infection. Intestinal intubation and small bowel internal fixation were performed on cases with extensive dissection to avoid adhesion intestinal obstruction after surgery, which led to surgical failure.

5. Prevention and treatment of complications

When intestinal fistula is accompanied by severe abdominal infections, gram-negative bacillus sepsis and multiple organ dysfunction often occur. Septic shock, gastrointestinal bleeding, jaundice, acute respiratory distress syndrome, and conscious coma should be strengthened. Treat promptly.