diagnose
At present, anal fistula is divided into four categories according to the relationship between anal canal and sphincter. 1. The anal fistula between sphincter is mostly low anal fistula, the most common one, accounting for about 70%, which is the result of abscess around anal canal. Fistula only passes through the internal sphincter, and often there is only one external orifice, which is close to the anal margin, about 3 ~ 5 cm. A few fistulas are upward, forming a blind end between the rectus muscle and the longitudinal muscle or penetrating into the rectum to form a high sphincter fistula.
2. Trans-sphincter anal fistula can be low or high anal fistula, accounting for about 25%, which is the result of ischiorectal abscess. Fistula passes through the internal sphincter, and there are often several external orifices between the superficial part and the deep part of the external sphincter, and the branches are connected with each other. The external orifice is close to the anal margin, about 5cm, and a few fistulae pass upward through levator ani to reach the connective tissue near the rectum, forming pelvic rectocele fistula.
3. Anal fistula above sphincter is a high anal fistula, which is relatively rare, accounting for 5%. The fistula goes up through levator ani, and then down to the ischiorectal fossa to penetrate the skin. Because fistula often involves the anorectal ring, it is difficult to treat, and it is often necessary to operate by stages.
4. External anal fistula is the least common, accounting for 65438 0%, which is the result of pelvic and rectal abscess combined with ischiorectal fossa abscess. The fistula passes through levator ani and communicates directly with rectum. This kind of anal fistula is mostly caused by Crohn's disease, intestinal cancer or trauma, and its primary focus should be paid attention to during treatment. The above classification is more detailed in high and low positions, which is conducive to the choice of surgical methods.
If there are external openings on the left and right sides of anal canal, it should be considered as "horseshoe-shaped" anal fistula. This is a special type of anal fistula, which runs through the sphincter and is also a high bending anal fistula. Fistula surrounds the anal canal and passes from one side of the ischiorectal fossa to the opposite side, thus becoming a semi-circular shape, such as horseshoe shape. There is an inner opening near the tooth line, and the number of outer openings can be multiple, which are scattered on the left and right sides of the anus, and many branches spread around. Horseshoe anal fistula can be divided into two types: anterior horseshoe and posterior horseshoe. The latter is more common because the tissue behind the anal canal is loose in the front, and the infection is easy to spread. What are the rules of the external and internal mouth of anal fistula? Goodsell (1900) once suggested: Draw a horizontal line in the anus. If the external orifice of anal fistula is in front of this line, the fistula often goes straight into the anal canal, and the internal orifice is located at the corresponding position of the external orifice; If the external orifice is behind the horizontal line, the fistula is often curved, and the internal orifice is mostly in the middle of the anal canal, which is generally called Goode's law. Anal fistula mostly conforms to the above rules, but there are exceptions. For example, the high horseshoe anal fistula in front may be curved, and the low perianal abscess in the back may be straight. Clinically, it is observed that the straightness and curvature of anal fistula are not only related to the front and back of anal canal, but also related to the high and low position of anal fistula and the distance from the external orifice to the anal margin. Cirocco( 1992) made a retrospective analysis of a group of cases of anal fistula to test the accuracy of Goodsell's rule in predicting the course of anal fistula. It was considered that this rule was quite accurate in predicting the course of anal fistula of posterior external orifice, especially for female patients, 97% of the internal orifice was located in the posterior median anal recess, but it was not accurate in predicting anal fistula of anterior external orifice, and only 49% of radial fistula met this rule because of GOOD.
Digital rectal examination: there is mild tenderness in the inner mouth, and a few can be palpated with induration. Probe examination is only used for treatment, but generally can not be used as diagnosis to prevent fistula wall puncture and false internal orifice. X-ray film shows the distribution of fistula by injecting 30% ~ 40% iodized oil from the external mouth, which is mostly used for high anal fistula and horseshoe anal fistula.
Imaging examination: Yang (1993) 17 cases were clinically suspected of anorectal abscess or fistula, 6 cases were clinically suspected of abscess, and anus ultrasound AUS examination also showed abscess; In addition, 82%(9/ 1 1) AUS found fistula, but routine clinical examination failed to find it. Lonnies (1994) compared AUS with magnetic resonance imaging, and thought that the former was sometimes valuable for the diagnosis of interssphincter fistula, but could not diagnose external sphincter fistula and trans-sphincter fistula, while the latter had absolute advantages and accuracy for complicated high anal fistula, horseshoe anal fistula and difficult cases that were difficult to diagnose clinically.
Treatment measures
Anal fistula cannot heal itself and must be treated surgically. The principle of surgical treatment is to completely cut the fistula, and if necessary, cut off the scar tissue around the fistula at the same time, so that the wound will gradually heal from the base up. According to the depth and bending degree of fistula, thread-drawing therapy, anal fistula incision or resection can be selected. In a few cases, primary suture or free skin grafting after anal fistula resection is feasible. (1) thread-drawing therapy
This is a slow incision of fistula. Using the mechanical action of rubber band or medicine thread (the medicine thread still has drug corrosion effect), it is painstaking to block the blood supply of the tissue at the ligation site and gradually oppress the blank; At the same time, the ligature can be used as the drainage of the fistula, so that the exudate in the fistula can be discharged and acute infection can be prevented. In the process of surface tissue cutting, the basal wound began to heal gradually at the same time. The biggest advantage of this method of gradually cutting off the fistula is that although the anal sphincter is cut off, it will not change its position due to excessive contraction of the sphincter, and generally it will not cause anal incontinence.
This method is suitable for simple straight fistula with low or high internal and external orifices within 3 ~ 5 cm from anus, or as an auxiliary method for incision or resection of complex anal fistula:
1. method
(1) lateral position: firstly, tie a rubber band at the end of the probe, and then gently probe the probe head inward from the external opening of the fistula to find the internal opening near the anal canal tooth line; Then put your index finger into the anal canal, touch the probe, bend the probe and pull it out of the anal orifice. Be careful not to use violence when inserting the probe, so as not to cause false lanes.
⑵ Pull out the probe completely from the internal opening of the fistula, so that the rubber band can enter the fistula from the external opening of the fistula.
(3) Lift the rubber band, cut the skin layer between the inner and outer openings of the fistula, tighten the rubber band, and clamp the subcutaneous tissue with hemostatic forceps; Tighten the rubber band with thick silk thread under hemostatic forceps, do double ligation, and then loosen the hemostatic forceps. Vaseline gauze was applied to the incision, and hot 1∶5000 potassium permanganate solution was used for sitz bath and dressing change every day after operation. Generally, the anal fistula tissue is cut with a rubber band about 10 day after operation, and the wound can heal after 2 ~ 3 weeks.
The advantage of this law is that
(1) Simple and quick operation with little bleeding.
⑵ When the rubber band does not fall off, the skin incision generally does not "bridge".
(3) The dressing change is convenient.
3. Keep the key point of messenger wire success
(1) To accurately find the internal orifice, generally, when the probe passes through the internal orifice, if there is no bleeding, it proves that the position of the internal orifice is relatively correct.
⑵ The wound must start from the base, so that the wound in the anal canal can heal first, and the surface skin can be prevented from premature adhesion and sealing. Generally, the rubber band can fall off in 7 ~ 10d. If it hasn't fallen off after 10d, it means that the silk thread used to tie the rubber band is loose and needs to be tightened again.
(2) Anal fistula incision
The principle of operation is to completely cut the fistula and remove the scar tissue on both sides of the incision, so that the drainage is smooth and the incision is gradually healed. This method is only suitable for low straight or arc anal fistula. The operation method is as follows.
1. The operation of correctly probing the internal orifice to find the internal orifice is the same as that of thread-drawing therapy. After probing the inner mouth, pull the probe out of the anus. If the fistula is bent or branched, and the probe can't penetrate into the inner port, inject a small amount of 1% methylene blue solution from the outer port to determine the position of the inner port, then probe into the inner port from the outer port with a slotted probe, and gradually cut the exploration pipeline until it penetrates into the inner port. If the internal orifice cannot be found after careful exploration, the anal sinus suspected of being sick can be treated as the internal orifice.
2. Incise the fistula and completely remove the marginal tissue. Incise all the surface tissues of the fistula, from the external orifice to the internal orifice and the corresponding anal sphincter fibers. After the fistula is cut, check whether there is any branch pipe, and if there is, cut it. After the fistula is completely cut, the rotten granulation tissue will be scraped clean. Generally, it is not necessary to cut the whole fistula to avoid the wound being too large. Finally, trim the edge of the wound to make it V-shaped, with a small opening at the bottom, which is convenient for the deep wound to heal first.
3. In anal sphincter amputation, it is necessary to carefully understand the relationship between probe position and anorectal ring. For example, when the probe enters the lower part of the anorectal ring, although the fistula, most of the external sphincter and the corresponding internal sphincter are cut off, anal incontinence will not be caused because the puborectal muscle is preserved. For example, if the probe enters the rectum above the anorectal ring (such as anal fistula above the sphincter, anal fistula outside the sphincter), do not do fistula incision, but do thread-drawing therapy or thread-drawing staging surgery. In the first stage, the subcircular fistula is cut or removed, and the supraannular fistula is hung with thick wire and tied tightly. In the second operation, after most of the external wounds healed, the anorectal ring was adhered and fixed, and then the anorectal ring was cut along the silk thread
After fistula incision, the granulation tissue of the posterior wall can be scraped off with a curette, which is generally not needed to be taken out to reduce bleeding and avoid damaging the sphincter of the posterior wall. The resected fistula tissue should be sent for pathological examination.
4. Wound treatment after wound treatment is often related to the success or failure of surgery. The key is to keep the wound healing from the base to the surface. Change the dressing once a day, preferably after defecation, and the filling dressing in the wound will gradually decrease until the wound in the anal canal heals. A digital rectal examination every few days can dilate anal canal, prevent bridge adhesion and avoid false healing.
(3) Anal fistula resection
Unlike incision, the fistula is completely removed until the healthy tissue. This method is also suitable for low anal fistula with fiber tube.
Methods: 1% methylene blue was injected from the external orifice of the fistula, and then the probe was gently inserted from the external orifice and passed through the internal orifice. Clamp the skin of the external orifice with tissue forceps, cut the skin and subcutaneous tissue around the external orifice of the fistula, and then cut off the skin, subcutaneous tissue, tube wall stained with methylene blue, internal orifice and all scar tissue around the fistula with electrotome or scissors along the probe direction, so as to completely open the wound. After careful hemostasis, fill the wound with iodoform gauze or vaseline gauze.
(4) anal fistula resection and primary suture
This method started with Tuttle( 1903), but it failed to be popularized, probably because the theory was insufficient. The operation result is not ideal; Many anorectal surgeons object. At 1949, Starr put forward this method and some effective measures, and the effect was satisfactory before popularization. This method is only suitable for simple or complicated low rectal fistula, and the effect is better if the fistula is in a hard rope shape. Key points of operation: ① Prepare the intestine before operation, use antibiotics before and after operation, and control the stool for 5 ~ 6 days after operation. ② All fistulas should be removed, leaving fresh wounds and ensuring no granulation tissue and scar tissue. ③ Don't remove too much skin and subcutaneous fat to facilitate wound suture. Therefore, the anal fistula with high bending should not be sutured, because it has many branches, and it often needs to remove too much tissue to cut off its branches. ④ Each layer of wound should be completely stitched and aligned, leaving no dead angle. ⑤ Strict aseptic operation during operation to prevent pollution, such as fistula. Based on 1064 cases of anal fistula excision and suture reported in domestic literature, the primary healing rate was 73.4% ~ 97.6%, and the wound healing time was 20 ~ 22 days. Most patients with low primary healing rate are complicated with high anal fistula.
(5) Skin grafting after anal fistula resection
After anal fistula resection, if the wound is too large and superficial and there are no special complications, free skin grafting can be considered. One-stage suture with anal fistula resection is needed before and after operation. Key points of operation: ① The wound should be flat and the bleeding should be completely stopped. ② The skin in the free skin graft area should be completely sutured and fixed with pressure to prevent gas or blood from remaining under the wound, which is one of the important measures for successful operation. (3) If there is a lot of bleeding on the wound, skin grafting should be postponed, that is, vaseline gauze should be applied to the wound first, and then free skin grafting should be done after 2 ~ 3 days. Hughes (1953) reported 40 cases, of which 30 cases were completely successful and the others survived. Goliher (1975) reported 22 cases, all of which were low anal fistula with poor effect. Only 13 cases survived completely.
(6) Treatment of horseshoe anal fistula
Fistula incision and thread-drawing therapy should be adopted. For example, in the case of posterior horseshoe anal fistula, firstly, the slotted probe is inserted from the external ports on both sides, and the fistula is gradually cut until the pipelines on both sides meet near the posterior midline, and then the internal port is carefully explored with the slotted probe. The internal orifice is mostly on the tooth line near the posterior midline of anal canal. If the fistula passes under the anorectal ring, the subcutaneous and superficial parts of the fistula and the external sphincter can be completely cut off at one time. If the internal orifice is too high and the fistula passes above the anorectal ring, thread-drawing therapy must be adopted. That is, the fistula under the subcutaneous part and superficial part of the external sphincter is cut, and then the rubber band is inserted from the remaining pipeline mouth, led out through the inner mouth and tied to the anorectal ring, so that anal incontinence caused by cutting the anorectal ring at one time can be avoided. Then cut off the skin and subcutaneous tissue at the edge of the incision to open the wound and scrape off the granulation tissue on the fistula wall. The wound was filled with iodoform or vaseline gauze.
(7) The sliding mucosal flap moves forward to close the internal orifice.
After the fistula and internal orifice are completely removed, the mucosal flap is used to repair the rectal defect, which actually includes part of the thickness of the rectal wall to increase its strength.
The advantages of this method are as follows: ① most of the sphincter is reserved, which is suitable for rectovaginal fistula and high trans-sphincter anal fistula; ② Scar formation is less; (3) avoid anatomical deformity; ④ There is no need for protective enterostomy shunt. Aquilar et al. (1985) used this method to treat high trans-sphincter anal fistula 189 cases. The recurrence rate is only 2%, but underwear pollution and stenosis are 8%, mild exhaust incontinence is 7%, and fecal incontinence is 6%. Wedell et al. (1987) reported 30 cases, and 29 cases had good results. Jones et al. (1987) used this method to treat anal fistula caused by Crohn's disease, and the success rate was only 57%, while the success rate of people without Crohn's disease was higher. However, some authors use the method of directly sewing the internal opening.
postoperative care
Dressing change of wound after anal fistula operation is the key to successful operation. Even if the operation is successful, if the dressing change of the wound is ignored, the operation is often easy to fail. Therefore, the attending doctor must change the dressing himself, or at least check the wound regularly. Precautions for dressing change: ① Sit bath and washing: Sit bath every day after operation, especially after defecation. It is necessary to ensure that the wound is clean and accelerate the healing. Large wounds should be cleaned with hydrogen peroxide first, and then with warm physiological saline or antibiotic solution. Maintain a certain pressure when cleaning, so that the cleaning solution can reach every corner of the wound. ② Dressing: The dressing in the wound surface can prevent the adhesion of the wound surface (skin bridging), so the bottom of the wound surface should be large and can heal from bottom to top. If pus is found in the wound when the dressing is taken out, suggesting that there is pus cavity residue, the drainage should be expanded immediately, otherwise the wound will not heal. ③ Digital rectal examination: It can be found whether there is dead space, pus and anal stenosis tendency in the wound. If there is, it is necessary to perform anal dilatation treatment regularly. Therefore, regular digital rectal examination should be carried out.
etiology
Perianal abscess can be divided into two types: one is related to anal gland and anal fistula, which is referred to as "primary acute anal fistula abscess", and "fistula abscess" is more common; One kind has nothing to do with anal gland and anal fistula, and is called "acute non-anal gland non-fistula abscess", which is rare for short. Anal fistula is mostly caused by systemic purulent infection, and a few are specific infections, such as tuberculosis, Crohn's disease and ulcerative colitis. The secondary infection of anorectal trauma can also form anal fistula, and the malignant tumor of anal canal can also fester into fistula, but they are relatively rare, which is obviously different from the general purulent anal fistula.
Some people speculate that the influence of sex hormones is the main cause of anal fistula. By puberty, the human body's own sex hormones began to be active, and then some sebaceous glands, especially anal glands, began to develop and proliferate, and the proliferation of young men was more obvious than that of women. Due to the exuberant secretion of anal gland, if the anal gland is not excreted smoothly or the anal gland tube is blocked, it is easy to be infected and cause anal adenitis, which may explain why the incidence of anal fistula is higher in young men. Female anal canal catheter is straight, unlike male, and secretion is not easy to deposit, so the incidence of female anal fistula is low. When people reach old age, anal glands atrophy together with other sebaceous glands, so anal fistula is rare in the elderly.
pathological change
Anal fistula includes primary internal orifice, fistula, branch pipe and secondary external orifice. The internal orifice is the entrance of the infection source, which is more common in and near the anal sinus and on both sides of the posterior midline, but it can also be located in the lower rectum or any part of the anal canal. Fistula are straight and curved, and a few have branches. The external orifice, that is, the site of abscess rupture or incision and drainage, is mostly located outside the skin around the anal canal. Because the primary lesion continuously enters the pipeline through the internal orifice, the pipeline winds around the internal and external sphincter, the pipeline wall is composed of fibrous tissue, and there is granulation tissue in the pipeline, so it will not heal for a long time. Generally, simple anal fistula has only one internal opening and one external opening, which is the most common. If the external orifice is temporarily closed and the local drainage is not smooth, it will gradually become red and swollen, thus forming an abscess. The closed external orifice may be pierced again, or another external orifice may be formed elsewhere. This kind of anal fistula is called complex anal fistula, that is, it has one internal orifice and multiple external orifices. However, some people think that complex anal fistula should not be divided by the number of external orifices, but refers to those whose main pipeline involves the anorectal ring or above. Although this kind of anal fistula has only one external orifice and one internal orifice, its treatment is complicated, so it is called complex anal fistula. On the contrary, sometimes anal fistula has multiple external orifices, but the treatment is not complicated.
clinical picture
Anal fistula often has a history of perianal abscess self-rupture or incision and pus discharge, and then the wound does not heal for a long time and becomes the external orifice of anal fistula. The main symptom is that a small amount of pus repeatedly flows out of the outer mouth, polluting underwear; Sometimes pus can irritate perianal skin and cause itching. If the external orifice is temporarily closed, pus accumulates and local swelling occurs, swelling and pain will occur. The closed external orifice may be pierced again, or another new external orifice may be formed nearby. If this happens repeatedly, a plurality of external orifices may be formed to communicate with each other. If the fistula drainage is smooth, there is no local pain, only slight swelling and discomfort, patients often don't mind. Examination: The external orifice is nipple or granulation tissue bulge, and a small amount of pus flows out under pressure. Low anal fistula usually has only one external orifice. If the fistula is shallow, a hard rope can be felt under the skin, leading from the external orifice to the anal canal. The position of high anal fistula is often deep, and it is not easy to touch the fistula, but there are often multiple external orifices. Due to the stimulation of secretions, perianal skin often thickens and turns red.