Understanding of Western Medicine:
Anal fistula and perianal abscess belong to the two pathological stages of purulent infection in the perianal space. The acute stage is perianal abscess, and the chronic stage is anal fistula. Therefore, anal fistula is a natural outcome of perianal abscess, and its etiology and pathology are consistent with perianal abscess. The etiology and pathology of the formation of perianal abscess have been discussed above, and now only the pathological process of perianal abscess developing into anal fistula is introduced as follows:
After the perianal abscess becomes pus, the perianal skin or anorectal mucosa is ulcerated or pus is incised. After the pus is fully drained, the abscess cavity gradually shrinks, and the connective tissue on the wall of the abscess cavity is proliferated, so that the abscess cavity is narrowed and a straight or curved duct is formed, which becomes an anal fistula. The reasons for its difficulty in healing are as follows:
1. The internal mouth and the original infection foci continue to exist. Although the abscess is ulcerated or incised and drained, the primary infection focus is anal cryptitis and anal gland infection. Intestinal contents can also continue to enter from the inner mouth.
2. Due to the feces, intestinal fluid and gas in the intestinal cavity continue to enter the fistula, long-term chronic inflammation and repeated infections are formed, which makes the connective tissue hyperplasia and thickening of the tube wall, forming a fibrotic tube wall, which is difficult to collapse and close. In addition, the pipeline is often bent and narrow, resulting in poor drainage.
3. Fistulas often pass through the anal sphincter at different heights. Factors such as local inflammation and stimulation can cause spasm of the anal sphincter, hinder the drainage of pus in the lumen, and adversely affect the healing of the fistula.
4. The outer mouth is narrow, sometimes closed and sometimes ulcerated, the abscess cavity is not drained smoothly, and pus accumulates, which can lead to recurrence of abscesses, and pierce the skin to form new fistulas and outer mouths.
From the perspective of pathological anatomy, anal fistula is generally composed of three parts: internal mouth, fistula and external mouth.
Inner mouth: The inner mouth can be divided into two types: primary inner mouth and secondary inner mouth. About 95% of the primary internal orifice is located in the anal crypt on the plane of the dentate line, which is often the primary infected anal crypt, of which about 80% are on both sides of the midline at the back of the anal canal. It can also be in the lower rectum or any part of the anal canal. The majority of secondary internal ostium is iatrogenic, and the most common cause is improper probe examination or surgical operation. In a few cases, the infection spreads and the abscess ruptures into the rectal tube. The secondary internal mouth can be located on the dentate line or the rectal mucosa above the dentate line. Generally, there is only one inner mouth, a few can have two, and multiple inner mouths are rare.
Fistula: A fistula is a pipe connecting the inner mouth and the outer mouth. It can be divided into main pipes and branch pipes.
Supervisor: The supervisor refers to the pipe connecting the original internal port and the original external port. Some of the supervisors walk straight and some are curved. Some are thick and some are small. Nessetrod believes that the running of the fistula is related to the direction of perineal lymphatic drainage. Perianal lymphatic drainage flows into the inguinal lymph nodes, such as a fistula formed by an infection of the anal gland in front of the anal canal. It is usually on the same side of the front of the anus. For example, the fistula formed by the infection of the anal glands behind the anus, the ducts are often bent forward, longer, shallow or deep.
Branch pipe: The branch pipe is the pipe connecting the main pipe and the secondary outlet. It is mostly caused by poor drainage of the main pipe or closed outer mouth, which forms an abscess again and spreads to the surroundings. Repeated recurrence can form multiple branches. If a new abscess is formed, the inflammation is controlled, the pus is absorbed or the original mouth ulcers, and it does not penetrate the skin or mucous membrane in other parts, then a blind duct will form.
Generally, the inner wall of anal fistula is composed of non-specific inflammatory granulation tissue, and there are a lot of fibrous tissue in the outer layer of the wall. There are more neutrophils, lymphocytes, plasma cells and other infiltrations during acute infection. Because the fistula is directly connected to the rectum and anal canal, feces can often enter the fistula, so that multinucleated foreign body giant cell reactions and more monocytes appear in the fistula tissue, and sometimes more eosinophilic cell infiltration can be seen. In tuberculous anal fistulas, there are many different types of tuberculous granulation tissue composed of epithelial cells, lymphocytes, and Langhan's giant cells, and sometimes caseous necrosis can occur. In the foreign body granulation formed by the foreign body reaction in the fistula tissue, the foreign body is often seen inside and outside the foreign body multinucleated giant cells, the monocytes are scattered, they do not form nodules alone, and there is no caseous necrosis.
Outer mouth: The outer mouth is the opening of the fistula leading to the perianal skin. There are two types of primary outer mouth and secondary outer mouth. The primary external orifice is the pus orifice formed by the first rupture or incision of the perianal abscess. After a new abscess secondary to an external orifice fistula, a new pus in another place was ulcerated.
Understanding of Chinese Medicine:
Chinese medicine's understanding of the cause of anal fistula can be summarized into the following three directions.
1. Exogenous rheumatism caused by dry heat. For example, the "Six Books in the Hejian" states: "The cover is covered with wind and heat, and the valley flows out, which spreads to the lower part, so that the anus is swollen, the knot is like plum and plum nucleus, and even becomes a fistula." : "Leakage is virtual and damp heat."
2. Over-eating mellow wine, heavy taste, fatigue and worry, caused by overwork. For example, the "Compilation of Medical Records of External Diseases" written by Yu Tinghong in the Qing Dynasty said: "Patients with anal leakage are all insufficient in the liver, spleen and kidney, three yin, qi and blood... Tendons and veins were dissected horizontally, and the viscera were injured."
3. Hemorrhoids do not heal and become fistulas. For example, "Theories on the Sources of Diseases" says: "Hemorrhoids do not succumb for a long time, and become fistulas." Another example is "Hemorrhoids does not heal, damp heat and stasis for a long time, but penetrates the intestinal points and destroys the muscles. The bone marrow is damaged, and it is missed."