bubble_chart Overview

Colonic fistula is a common surgical pathological condition characterized by abnormal channels formed between the gastrointestinal tract due to various reasons. Pathological channels between the intestinal tract and other hollow organs or between the intestinal tract and the body surface are all classified as intestinal fistulas. When occurring in the colon, it is referred to as a colonic fistula, which can be divided into two types: external and internal fistulas. An external fistula is when intestinal contents are discharged outside the body, while an internal fistula is when the fistula connects to another part of the intestine or other hollow organs. Conditions such as large intestine cancer, injury, inflammatory perforation, adhesive obstruction, and torsion that require surgical treatment can lead to poor anastomotic healing due to systemic and local factors, including membrane injury and local infection, resulting in the discharge of intestinal contents. Clinical reports generally indicate that the incidence of intestinal fistula in intestinal anastomosis is 5-10%.

bubble_chart Pathogenesis

Due to the different causes of intestinal fistula formation, the size and length of the fistula vary greatly. Based on the morphology of the intestinal fistula, colonic fistulas are generally divided into three categories: ① Complete fistula: Mostly caused by surgery, the entire intestinal cavity is everted and exposed outside the abdominal wall, and all or most of the intestinal contents flow out through the fistula. ② Tubular fistula: Can be pathological or post-surgical, especially due to the hardness of abdominal drainage tubes compressing the colon, leading to necrosis of the intestinal wall and forming a fistula. The fistula is small and the fistula tract is long, with most of the intestinal contents flowing into the distal intestine and only a small portion flowing out through the fistula. ③ Lip fistula: Mostly caused by trauma, the intestine is closely attached to the abdominal wall, and part of the intestinal membrane is everted at the fistula site, with part of the intestinal contents flowing out through the external fistula and part flowing into the distal intestine.

The fistula on the intestinal wall can be single or multiple, and the external fistula on the abdominal wall can also be single or multiple. Although intestinal fistulas caused by surgery or trauma are initially single, sometimes due to the splitting of the abdominal wall incision, exposure of the intestinal loop, severe infection or edema of the intestinal wall, injury during dressing changes, or intestinal cavity pressure, multiple fistulas can form.

Colonic external fistula is a low fistula, and its serious harm is: on one hand, abdominal infection causing severe peritonitis, and on the other hand, loss of water and electrolytes and malnutrition.

bubble_chart Clinical Manifestations

After colon repair or intestinal resection and anastomosis due to colon injury, inflammation, or tumors, anastomotic leakage fistula disease often occurs 4-5 days post-surgery. Initially, abdominal pain may lessen after the surgery, but then persistent abdominal pain worsens, often accompanied by toxemia, such as elevated body temperature, increasing abdominal tenderness, rebound pain, and muscle tension. At this point, intra-abdominal infection or the possibility of intestinal fistula formation should be considered first. The presence of intestinal contents flowing out from the abdominal incision or drainage site is reliable evidence of an intestinal fistula, but accurately determining the location of the fistula's internal opening is challenging. Generally, ileum fistula discharge often appears as yellow porridge-like or thin paste, while colon fistula discharge is semi-formed or unformed feces.

bubble_chart Auxiliary Examination

1. Oral administration of activated charcoal powder or injection of methylene blue solution through a gastric tube, with the outflow of charcoal powder or blue liquid from the wound, confirms the presence of an intestinal fistula. The time from oral administration or injection of the drug to its discharge through the fistula can also help determine the location of the internal fistula opening.

2. X-ray examination: Reviewing an upright abdominal X-ray may show an increase in free gas under the diaphragm, which can also suggest the possibility of an intestinal fistula. (Gas may accumulate under the diaphragm after surgery but should gradually decrease.)

3. Fistulography: If a fistula is present, a catheter can be inserted through the fistula to inject a contrast agent, which helps determine the presence, location, size, direction of the fistula, and the condition of the surrounding intestines.

4. Barium gastrointestinal examination: This helps understand the location and size of the fistula and whether there is an obstruction distal to the fistula.

5. B-type ultrasound examination: This is mainly used to determine the presence, location, and size of any residual infection in the abdominal cavity. {|104|}

bubble_chart Diagnosis

The discharge of fecal-like material from an abdominal wound is definitive evidence for diagnosing an intestinal fistula. Diagnosis can also be confirmed by examination revealing an abnormal passage between the colon and the abdominal wall.

bubble_chart Treatment Measures

I. Principles of Colonic Fistula Treatment

1. Ensure the maintenance of systemic nutrition and water-electrolyte balance to enhance the self-healing ability of the intestinal fistula.

2. Administer large doses of antibiotics to control abdominal infection and perform thorough drainage at an appropriate time.

3. Attempt to understand the location and size of the fistula.

4. Protect the skin around the external fistula.

5. Try to identify the cause of the intestinal fistula and provide symptomatic treatment.

6. For difficult-to-heal external intestinal fistulas, choose an appropriate time for surgical treatment.

II. Intestinal Fistula

Corresponding treatment should be provided according to different stages:

First stage (7-10 days after fistula occurrence): The patient is in the initial stage where the fistula is not yet stable and infection is present. Severe intra-abdominal infection and local inflammation edema are present. Surgical repair of the intestinal fistula often fails and may lead to the spread of infection. The patient should be fasted, undergo gastrointestinal decompression, and receive parenteral nutrition to correct general conditions. Antibiotics should be administered, and intra-abdominal infection foci should be thoroughly drained. Intestinal contents should be completely drained from the abdominal cavity (wound exposure should be promptly cleared or catheter drainage performed).

Second stage (10-30 days): After the first stage of treatment, the patient gradually recovers. The fistula, after drainage or treatment, becomes a "controlled" fistula. If the infection remains severe or continues to spread, active infection control and enhanced nutrition are necessary. Total parenteral nutrition is particularly essential to provide calories and nitrogen sources.

Third stage (1-3 months): After 1-2 stages of treatment, the fistula that has shown good results has healed or stabilized. Since the intestinal fistula is low, it has little impact on nutrition. However, if the fistula does not heal, the factors preventing healing should be promptly identified. Common reasons include:

① Obstruction distal to the fistula; ② Epithelialization of the fistula tract tissue; ③ Adhesion of the colonic membrane to the abdominal wall, causing the fistula to become lip-shaped; ④ Presence of foreign bodies at the fistula site; ⑤ Poor drainage of abscesses near the fistula; ⑥ Presence of special infections or tumors.

During this period, the focus is on identifying the reasons for the non-healing of the fistula and controlling intra-abdominal infections, especially interintestinal abscesses. If highly suspected, timely exploratory laparotomy for abscess drainage should be performed. Of course, if confirmed by B-ultrasound, puncture and aspiration of pus can be performed under its guidance, and antibiotics can be injected to alleviate concerns about extensive intra-abdominal adhesions and potential intestinal injury during surgery.

Fourth stage: For patients with unhealed intestinal fistulas, if the abdominal infection is controlled and the local condition of the fistula is good, elective surgery can be considered to eliminate the disease cause and close the fistula. If there is obstruction distal to the fistula, it should be relieved before repairing the fistula. For simple lip-shaped or tubular fistulas, the fistula can be inverted into the intestinal cavity without excessive exploration of the abdominal cavity. Of course, if there is a special infection or tumor at the anastomosis site, the lesion should be resected and anastomosed.

III. Perioperative Management

1. For emergency patients, promptly correct typical edema and electrolyte disturbances and promptly correct shock to prevent prolonged intestinal wall ischemia. Postoperatively, correct anemia and malnutrition.

2. For elective surgery, address malnutrition. If necessary, provide intravenous nutrition to improve pre- and postoperative plasma protein, hemoglobin, and blood vitamin C levels, and prepare the intestines preoperatively.

IV. Precautions During Surgery

1. During intestinal resection and anastomosis, the tissue at the resection site that has been clamped with vascular forceps should be excised. For intestinal stenosis caused by intestinal lesions, intestinal torsion, intussusception, or mesenteric vascular injury and thrombosis, it is preferable to resect more to ensure normal tissue at the intestinal ends. Generally, the intestinal ends should be at least 3-5 cm away from the necrotic (or diseased) intestinal segment.

2. Ensure good blood circulation at the intestinal anastomosis site. When resecting the intestine, resect more on the opposite side of the mesentery to ensure blood supply. When separating the mesentery, do not separate too much, not exceeding 1 cm from the intestinal end. When suturing, the mesenteric side should include part of the avascular mesentery to ensure blood supply without injuring the supplying vessels.

3. During intestinal resection and anastomosis, there should be no local infection or hematoma present. The suturing must ensure that the intestinal mucosa is inverted to guarantee complete serosa-to-serosa healing at the intestinal ends.

bubble_chart Differentiation

After large intestine surgery, if there is residual intra-abdominal infection, drainage is required to determine the presence of an intestinal fistula. For patients with abdominal wound dehiscence after large intestine surgery, if there is significant drainage, detailed observation is necessary. Only after confirming the absence of an intestinal fistula should intermediate stage (second stage) wound closure be performed.