Anal fistula

Introduction to anal fistula Anorectal fistula mainly invades the anal canal and rarely involves the rectum. It is often called anal fistula. It is a granulomatous duct that communicates with the skin of the perineal area. The inner mouth is located near the tooth line, and the outer mouth is located at the perianal and skin. The entire wall of the fistula is composed of thickened fibrous tissue, and a layer of granulation tissue is placed inside, which is not cured for a long time. The incidence rate is second only to sputum, more common in male young adults, and may be related to the secretion of sebaceous glands in one of the male sex hormone target organs. basic knowledge Sickness ratio: 0.05% Susceptible people: more common in male youth Mode of infection: non-infectious Complications: anal incontinence

Anal fistula

Abscess (25%):

There are 2 categories of anal canal rectal abscess: one is related to anal gland and anal fistula, which is called primary acute anal muscle fistula, which is more common in fistula abscess; one is not related to anal gland and anal fistula. It is called acute non-anal non-tubular abscess, abbreviated as non-tubular abscess; most of the anal fistula is developed from the former. Anal fistula is mostly caused by general purulent infection, and a few are specific infections, such as tuberculosis, Crohn's disease, ulcerative colitis. Rectal anal canal injury secondary infection can also form anal fistula, rectal anal canal malignant tumor can also be broken into fistula, but rarely seen, and the general purulent anal fistula is significantly different.

Sex hormones (30%):

Some people speculate that the effect of sex hormones is the main cause of anal fistula. In adolescence, the body's own sex hormones begin to be active, and then some sebaceous glands, especially the anal glands, begin to proliferate. Men are more proliferative than women, because the anal glands are exuberant, if anal is added If the gland is not excreted or the anal gland is blocked, it is easy to cause anal gland inflammation. This may explain why the incidence of anal fistula is higher in male young adults, while female anal ducts are straighter than men, and secretions are not easy to accumulate. The incidence of female anal fistula is low. When people reach old age, and other sebaceous glands generally shrink, the anal glands also shrink, so the elderly anal fistula is rare.

Pathogens (15%):

Anal fistula has primary internal mouth, fistula, branch tube and secondary external mouth. The internal port is the entrance to the source of infection. It is mostly in and around the anal sinus. It is more common on both sides of the posterior midline, but also in the lower part of the rectum. Or any part of the anal canal, the fistula has a straight bend, a few have branches, the external mouth is the site of the abscess or the incision, mostly located in the skin around the anal canal, because the pathogen continues to enter the pipeline through the mouth, plus the pipe distortion Walking inside, near the external sphincter, the wall of the tube is composed of fibrous tissue, and there is granulation tissue inside the tube, so it will not heal for a long time.

Generally, simple anal fistula has only one internal mouth and one external mouth. This type of anal fistula is most common in clinical practice. If the external mouth is temporarily closed and local drainage is not smooth, infection will gradually occur again, and an abscess will be formed again. Piercing or forming another external mouth in other places (Fig. 1), so repeated attacks, so that the extent of the lesion is enlarged or sometimes caused by several external mouths, which communicate with the internal orifice. This anal fistula is called complex anal fistula, that is, there is one The inner mouth and a plurality of external mouths, but some people think that the complex anal fistula should not be divided into the outer mouth, but the main fistula involving the anorectal ring or ring, although the anal fistula has only one outer mouth and one The internal mouth, but the treatment is more complicated, it is called complex anal fistula. On the contrary, although the anal fistula has multiple external mouths, the treatment is not complicated.

Anal fistula prevention

1, the establishment of normal dietary habits due to the occurrence of anal fistula and damp heat, for greasy diet, can be endogenous damp heat, so should not eat more, should eat more light foods rich in vitamins, such as mung beans, radish, melon and other fresh vegetables, fruits For the long-term unhealed anal fistula is mostly deficiency syndrome, eat more protein-containing foods such as lean meat, beef, mushrooms, etc.

2, timely treatment of anal sinusitis, anal papillitis to avoid anal canal rectal abscess and anal fistula.

3, anal burning discomfort, anal fall should promptly find out the reasons, timely treatment.

4, prevention and treatment of constipation and diarrhea is important to prevent anal canal rectal abscess, because dry stool is easy to scratch the anal sinus, coupled with bacterial invasion and infection, most of the diarrhea has proctitis and anal sinusitis, can cause inflammation Further development.

5, active treatment of active treatment may cause systemic diseases of the anorectal abscess, such as ulcerative colitis, Crohn's disease.

6, develop a good bowel habits, daily bath after a bowel movement to maintain anal clean, have a positive effect on prevention of infection.

7, active prevention and treatment of constipation and diarrhea constipation accumulated in the rectum, the fecal mass is easy to block the anal crypt caused by acute anal cryptitis, eventually forming anal abscess, in addition, dry stool and induration, easy to scratch the anal crypt during defecation Causes perianal infection, diarrhea for a long time, can also stimulate inflammation of the anal crypt, loose stools also easy to enter the anal crypt, induced perianal infection, so prevention and treatment of constipation and diarrhea is important to prevent perianal abscess and anal fistula formation.

Anal fistula complications Complications, anal incontinence

1, anal fistula bleeding: anal fistula surgery generally larger wounds, deeper wounds, the local blood vessels are rich, and thus more vascular damage, often postoperative bleeding. To this end, it is necessary to ligation of obvious bleeding points during surgery. For deep blood vessels that are not easy to be ligated, it is necessary to electrocautery and stop bleeding. After no bleeding, it is filled with gauze and pressurized to stop bleeding. For those who still have bleeding, the wound should be opened and the bleeding stopped.

2, urinary retention: urinary retention is less likely to occur after anal fistula, if urinary retention occurs, should be treated with hot compresses, acupuncture and other means, for those who have not urinated after various treatments, the use of catheterization.

Anal fistula symptoms Common symptoms Anal pain Anal short time Paroxysmal blunt pain Rectal anal internal pain Anal perineal perineal area Damp unclean Defecation Anal burning Anal abscess Anal skin flushing Anal itching Old fecal incontinence Anal sphincter transection

Symptoms and signs

A small amount of purulent, bloody, mucous secretions are discharged from the external orifice as the main symptom. Larger high anal fistula, because the fistula is located outside the sphincter, is not controlled by the sphincter, and often has feces and gas. Due to the stimulation of the secretions, the anus is moist, itchy, and sometimes forms eczema. When the external mouth heals, there is an abscess formation in the fistula, you can feel obvious pain, and may be accompanied by fever, chills, fatigue and other symptoms of systemic infection, abscess after perforation or incision and drainage. Symptoms are relieved. Repeated episodes of the above symptoms are clinical features of the fistula.

There are several symptoms of anal fistula:

Pus

The initial flow of anal fistula is more pus, yellowish and thick, and the smell of feces is heavy. For a long time, the pus gradually decreases, sometimes it is not, it is as thin as water. If it is too tired, the pus will increase, and there will be feces out.

2. Pain

When the anal fistula is unblocked, there is generally no pain. There is only a partial sensation of bulging, but there is also a pain due to the large internal mouth and feces flowing into the pipeline, especially when there is inflammation or inflammation.

Itching

Perianal pruritus can also be caused by pus continuously irritating the skin around the anus. It can also be associated with perianal eczema.

4. Systemic symptoms

Acute inflammatory phase or chronic complex anal fistula may be associated with systemic symptoms such as fever, anemia, weight loss and loss of appetite.

Anal fistula examination

1. The rectal examination has mild tenderness outside the mouth, and a few can be indurated.

2. Methylene blue staining method, white wet gauze is inserted into the anal canal and the lower end of the rectum, and 1 to 2 ml of methylene blue is injected into the fistula through the external mouth, and then the gauze in the anal canal is taken out, according to whether or not the gauze is stained with methylene blue. The stained site is used to identify the presence of the fistula and the internal orifice.

3. Probe probe The probe is inserted into the pipeline through the external port to clarify the position of the fistula and the location of the internal orifice. This method is generally performed under anesthesia during surgery. Improper operation or unfamiliarity may lead to false formation.

4. Fistula angiography injected 30% ~ 40% lipiodol from the external mouth, X-ray film can observe the distribution of fistula, mostly used for the diagnosis of high complex anal fistula and hoof-shaped anal fistula (Figure 6), Yang (1993) check clinical doubt There were 17 cases of anorectal abscess or fistula, 6 cases of clinically suspected abscess, anal canal ultrasound AUS examination also had abscess performance; another 82% (9/11) AUS found a fistula, but clinical routine examination failed to find.

5. Anal canal ultrasound sometimes has a definite value for sphincter spasm, but it is not possible to diagnose sphincter sphincter and sphincter spasm.

6. MRI examination Lunniss reported 35 cases of this method, the rate of coincidence with the surgical results were: primary anal fistula (85.7%), secondary fistula and abscess (91.4%), hoof-shaped sputum (64.3%), The internal mouth is 80%, so that the position of the anal fistula diagnosed by MRI is extremely accurate. The correct use of MRI can not only improve the success rate of surgery, but also monitor whether the complex anal fistula is completely healed.

Anal fistula diagnosis and identification

diagnosis

1, the history of patients often have a history of perianal abscess or incision of pus, after which the wound has not healed for a long time.

2, clinical manifestations repeatedly through the fistula out a small amount of pus, perianal abscess pain, perianal skin itching; puncture mouth has pus out, subcutaneous can touch the hard cord.

3. The auxiliary inspection probe can be inserted into the pipeline through the outer mouth; the methylene blue is injected through the outer mouth, the gauze in the anal canal is blue-stained, and the sputum angiography can display the image of the pipeline.

Differential diagnosis

1, suppurative sweat gland inflammation around the anus: This is the most easily misdiagnosed as anal fistula around the anal skin disease, because its main feature is the formation of abscesses in the perianal and left sinus. There are often bulges and pus at the sinus, and there are multiple external mouths, so it is easy to be misdiagnosed as multiple anal fistula or complex anal fistula. The main point of identification is the perianal suppurative sweat gland inflammation in the skin and subcutaneous tissue, a wide range of lesions, there may be numerous sinus openings, nodular or diffuse, but the sinus is shallow, not connected with the rectum, after cutting the sinus No pus and fistula, no internal mouth. Wiltz reported 43 cases of perianal suppurative sweat gland inflammation, 35 cases were newly diagnosed as anal fistula, hair follicle cyst, sinus and anal canal abscess, and had a history of more than 6 years before diagnosis.

2, pelvic osteomyelitis: pelvic osteomyelitis caused by pelvic suppurative or tuberculous lesions, often occurs in the perineal sinus, and the anal fistula is very similar. However, the former has no internal mouth, and the X-ray film shows lesions in the pelvis.

3, anterior tibial iliac crest: the abscess between the tibia and the rectum is formed in the vicinity of the coccyx, the fistula is located in the humeral fossa, the external port is often located on both sides of the caudal bone tip, the probe can be probed into 8 ~ 10cm, the fistula is parallel with the rectum.

4, tuberculosis of the appendix: slow onset, no redness, swelling, heat pain and other acute inflammatory changes, after the ulceration, the thin pus flows out, the outer mouth is large, the edges are not neat, and the long-term unhealed. X-ray films showed bone damage and tuberculosis in the appendix.

5, teratoma teratoma: after the rupture can form the anterior or posterior tibia. Large teratoma can highlight the appendix and is easy to diagnose; small asymptomatic tumors can be seen in the posterior rectum and smooth, lobulated masses. The X-ray film shows a lump between the tibia and the rectum, with an amorphous calcified shadow inside, visible bone or teeth.

6, advanced anorectal cancer: after the ulceration can form anal fistula, characterized by a hard lump, secretions are pus and odor. Pathological sections can be diagnosed.

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