Aortoenteric fistula

Introduction to aortic intestinal fistula Aortoenteric fistula (AEF) refers to the pathological communication between the aorta and adjacent intestinal tract. According to the cause of the disease, it can be divided into primary and secondary. The primary AEF is a history of aortic surgery, but the erosion of the arterial wall caused by the lesion of the aorta itself is directly penetrated into the adjacent intestinal cavity. Found in the duodenum; secondary AEF is due to the formation of pseudoaneurysm at the anastomotic stoma of the graft after aortic surgery, and then rupture into the intestine, so secondary AEF is also called graft (artificial blood vessel) - Intestinal fistula. Secondary AEF is much more common than primary. basic knowledge The proportion of illness: the incidence rate is about 0.006%-0.009% Susceptible people: no special people Mode of infection: non-infectious Complications: shock, sepsis

Aortic intestinal fistula

(1) Causes of the disease

1. Aortic lesions Primary AEF occurs mostly in the abdominal aorta, often due to atherosclerotic abdominal aortic aneurysm (negative type) expansion and erosion directly into the intestine, a rare cause is fungal , syphilitic or traumatic aneurysm caused by rupture, in addition to primary aortitis, arterial malignant tumor or metastatic tumor is also the main cause of aortic intestinal fistula.

2. Gastrointestinal diseases such as mesenteric tuberculosis, Salmonella, syphilis and fungal diseases, etc., when the intestinal perforation is accompanied by erosion of the abdominal aortic wall and internal hemorrhoids, duodenal diverticulitis perforation, stomach twelve Refers to the erosion of the abdominal aorta by perforation of intestinal ulcers.

3. Biliary and pancreatic diseases such as cholelithiasis, necrotizing pancreatitis, pancreatic cancer and other biliary and pancreatic lesions can also be broken by erosion of the abdominal aorta.

4. Aortic surgery with the extensive development of vascular surgery, endarterectomy, arterial resection after arterial intestine fistula, has been common, and its causes are many, such as improper technique of resection or vascular transplantation, anastomosis An abscess is formed around the mouth or the suture is not firm and fractured. The vascular anastomosis or autologous vascular graft is followed by a pseudoaneurysm, or the blood supply to the duodenum or duodenum is accidentally injured. It is reported that most of this sputum occurs after emergency resection of aneurysm rupture, while elective surgery is less common.

(two) pathogenesis

More than half of the primary AEF is due to dilated erosion of the infrarenal abdominal aortic aneurysm or direct penetration into the intestine, most of which occurs in the third and fourth duodenum (60% to 70%) of the retroperitoneum. Reckless et al (1972) summarized 131 cases of abdominal aortic aneurysm spontaneously breaking into the intestine, and found that 57% broke into the third or fourth segment of the duodenum, followed by the jejunum, stomach and sigmoid colon, The intestines are easily invaded by the third and fourth segments across the abdominal aorta as if entering the arch, and the anatomical location is fixed and located in the retroperitoneum.

Secondary AEF occurs after abdominal aortic reconstruction and can occur several months or even years after transplantation. Although the pathogenesis is not completely clear, the basic pathogenesis is the mechanical erosion of the abdominal aorta. The duodenum is caused by a pseudoaneurysm. The expanding arterial aneurysm or the expanding graft vessel compresses the duodenum in the front or the intestinal tube in the vicinity, which erodes the intestinal wall and causes ulceration to form AEF, causing digestion. Hemorrhage, another pathogenesis factor is due to the rupture of the anastomosis of the vascular graft, resulting in the formation of retroperitoneal hematoma and pseudoaneurysm, inflammation, or adhesion of the anastomosis to the intestine in front of it, mechanical compression leading to the intestine The wall becomes weak, the intestinal contents containing bacterial toxins and digestive enzymes ooze out, and the surrounding inflammation is spread into a pus cavity to spread to the anastomosis, so that the intestinal lumen communicates with the pseudoaneurysm, eventually forming AEF, and the pseudoaneurysm is not necessarily There is also an infection.

Aortic intestinal fistula prevention

The key to preventing recurrence is to prevent the occurrence of infection. It is necessary to apply broad-spectrum antibiotics. In addition to taking tissue and secretions for culture, it is necessary to repeatedly wash a large number of tissues before abdomen, and apply viable tissues such as omentum. The anterior vertebral fascia covers the repaired intestine and the stump of the abdominal aorta (a case where the external bypass bypasses the lower extremity circulation) to isolate the intestines and blood vessels (Fig. 1) for primary AEF Patients, if the replacement artificial blood vessel method is adopted, the PTFE artificial blood vessel is applied. The material is currently considered to have stronger anti-infective strength than the Dacron material, and postoperative CT or MRI examination is feasible to detect the recurrence of AEF in the early stage.

Aortic intestinal fistula complications Complications shock sepsis

Hemorrhagic shock and sepsis are common complications of this disease.

Aortic intestinal fistula symptoms Common symptoms Fever with cold war chills systolic murmur repeated bleeding fatigue abdominal pain weakness shock

The most common symptoms of primary and secondary AEF are gastrointestinal bleeding, abdominal pulsating masses and infections, elevated body temperature, and patients often complain of weight loss, weakness, weight loss, fever, abdominal pain or low back pain, but these are not The specific symptoms, if these symptoms occur in the months or years after abdominal aortic transplantation, should be given early to check the possibility of AEF, most of the secondary AEF patients with gastrointestinal bleeding, can For a large amount of bleeding, but also a small amount of bleeding, manifested as fecal occult blood, most of the bleeding is intermittent self-limiting, so-called signal bleeding, if the bleeding can lead to myocardial ischemia, lower limb necrosis, renal failure or Irreversible shock occurred, 66% of AEF patients reported gastrointestinal bleeding, 48% showed acute bleeding, others were chronic, old or repeated bleeding, but 94% reported bleeding symptoms due to graft or anastomosis A bacterial infection of the hematoma in the pseudoaneurysm formed at the mouth (due to surgical contamination or exudation of the nearby intestinal tract), so there is a patient with chills, fever, fatigue or drainage at the old incision .

Aortic intestinal fistula examination

1. Blood routine examination When a pseudoaneurysm is followed by a hematoma infection, the white blood cell count increases and the proportion of neutrophils increases.

2. Bacterial culture When hematoma infection occurs, blood culture and wound secretion culture can have cell growth, 75% are Staphylococcus aureus, Staphylococcus epidermidis or Escherichia coli, blood culture before surgery and transplanted blood vessels during reoperation The tissue cultured in and around it is consistent.

3. Esophagogastroduodenoscopy (EGD) is the most commonly used examination method, which can reach the fourth segment of the duodenum, exclude other stomach, duodenal bleeding, if the duodenum is found 3 or 4 segments with mucosal defects, clots or sutures found in the graft vessel wall or its anastomosis, can be clearly diagnosed, the diagnosis rate of EGD examination is about 80%, the best in the operating room.

4. Enhanced CT examination Abdominal and pelvic CT can be helpful for unexplained sepsis. In patients with AEF, CT examination can find fluid or gas around the graft vessel. In addition, if CT scan reveals tissue swelling around the graft vessel Or inflammation, gas around the edge of the arterial calcification, pseudoaneurysm, thickening of the intestinal wall nearby.

5. Angiography Sometimes the distal or proximal pseudoaneurysm of the vascular anastomosis and the contrast agent flow into the intestine, the diagnosis can be confirmed, but due to the extremely fast blood flow rate, the typical X-ray sign is rarely seen. Angiography can provide features and design reoperation of arterial anatomy.

6. Although MRI imaging has certain accuracy, there are still some problems in the diagnosis of AEF. MRI imaging may detect the infection of the graft accurately. If MRI is found, there will still be around the graft in March. The effusion, which suggests an infection, can be diagnosed in combination with other clinical indications, the muscles of the transplanted blood vessels, and the increased signal intensity, onT2-Weogted images, also reveal the possibility of infection.

7. Gastrointestinal sputum examination should be avoided as much as possible, even if the diagnosis can be made, but the sputum into the blood vessel has a certain risk, X-ray film examination, the use has been described before, and if the condition is stable, not a large number of digestive tract Bleeding, the marked red blood cell nuclear scan can be applied to detect the bleeding site.

8. Other examinations If the condition is stable, not a large number of gastrointestinal bleeding, you can use the labeled white blood cell scan to detect the bleeding site, and colonoscopy, sinogram, etc. are also helpful for diagnosis.

Diagnosis and diagnosis of aortic intestinal fistula

There are the following clues in the medical history or examination, and the aortic intestinal fistula should be suspected:

1 The patient had only a history of painless (or slightly painful, uncomfortable) abdominal pulsatile mass, and recently had abdominal pain or sudden increase in pain, and when it was involved in the lower back, it was often a precursor to aneurysm rupture;

2 abdominal umbilical cord can touch an expansive, pulsatile mass, and can hear systolic murmur, but the bleeding has intermittent characteristics, for the unstable condition, continuous bleeding of the gastrointestinal tract often requires surgical exploration to determine its Diagnosis, for patients with limited bleeding or intermittent bleeding, the need to check for the presence or absence of graft infection, with or without sepsis, imaging and endoscopy can provide direct and indirect evidence.

However, none of the various tests can indicate an extremely reliable diagnosis, which must be considered in conjunction with clinical signs, and sometimes a laparotomy is required to obtain a diagnosis.

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