Anal canal injury

　　The pathological changes of anal canal injury vary with the degree of injury, the nature of the injury, the method of action, the location, range, time, and whether there are injuries to other organs.

　　1. Anal puncture injury

　　Hard foreign objects such as metal, wood shavings, bamboo tips, etc., can cause injury to the anal and soft tissue of the buttocks when the human body falls from a height and the buttocks hit the ground. Most of these injuries are accidental. However, during the war against the United States in Vietnam, the Vietnamese people set up bamboo spikes, often causing American soldiers to fall into traps and be injured; in rural areas, it is common to see injuries caused by cattle horns, when a fierce water buffalo becomes angry and chases people running away, the fierce bull uses its horn to hit the buttocks, resulting in common injuries to the anal and soft tissue of the buttocks, and anal tearing.

　　2. Wound caused by firearms

　　During wartime, shrapnel and bullets hitting the anal area account for a very low proportion in war injuries. In the Chinese People's Liberation Army's counter-attack against Vietnam in 1979, rectal and anal injuries accounted for only 3.64%.

　　3. Contusion and laceration injury

　　Commonly seen in individuals with mental abnormalities or sexual deviations, causing injury by inserting foreign objects into the anal and rectal cavity; it can also occur due to medical reasons, such as when the patient contracts the anal sphincter forcibly due to fear during rectoscopy or sigmoidoscopy, and the examiner uses rough force; in addition, forgetting to remove the thermometer to measure rectal temperature can cause the thermometer to break and cut the anal sphincter, such injuries are usually mild; in anal surgery, such as improper anal fistula surgery, if anal incontinence occurs, it is more serious.

　　Early in anal canal injury, due to fecal contamination, it often complicates pelvic cellulitis, and in the long term, it can cause anal stricture and fecal incontinence.

　　1. Pelvic adhesionitis

　　Pelvic adhesionitis is a pelvic inflammatory disease, which can be divided into acute and chronic, and acute pelvic adhesionitis. Pelvic adhesion tissue is extraperitoneal tissue located behind the peritoneum in the pelvic cavity, on both sides of the uterus, and in the anterior space of the bladder. There are no obvious boundaries between the adhesion tissues in these areas. Acute pelvic adhesionitis refers to the initial inflammation of pelvic adhesion tissue, which is not secondary to the fallopian tubes or ovaries, but initially occurs in the adhesion tissue around the uterus and then spreads to other areas. Chronic pelvic adhesionitis. Chronic pelvic adhesionitis is often due to incomplete treatment of acute pelvic adhesionitis or poor physical condition of the patient, resulting in chronic inflammation.

　　2. Anal stricture

　　Anal stricture refers to the narrowing of the anal canal due to various reasons, which can cause symptoms such as difficulty in defecation, thin stools, anal pain during or after defecation, and a series of clinical symptoms. According to the onset time, it can be divided into congenital anal stricture and acquired anal stricture.

　　3. Fecal incontinence

　　Fecal incontinence is a symptom of defecation dysfunction, where the patient loses the ability to control排气 and defecation.

　　After anal canal injury, symptoms such as anal pain, bleeding, or incontinence, stricture leading to difficulty in defecation, and thin stools may occur. Early examination after injury may show lacerations and bleeding around the anal area and surrounding tissues. Patients with transverse rupture of the anal sphincter muscles often have fecal leakage and contamination. In cases with a longer duration, there may be severe local infection, and deep cellulitis of the gluteus maximus can be seen. Patients with a history of anal trauma and symptoms such as anal pain, bleeding, incontinence, and difficulty in defecation should be suspected of having anal canal injury. The diagnosis can be confirmed by the presence of blood-stained gloves, decreased or relaxed anal sphincter tension, damage to the anal canal wall, pain, and a feeling of emptiness.

　　There are currently no effective preventive measures for anal canal injury. Early detection and early diagnosis are the key to the prevention and treatment of the disease. In daily life, attention should be paid to avoid anal canal trauma, and during anal surgery, attention should be paid to intraoperative procedures.

　　Patients with anal canal injury should undergo a routine blood test, which shows an increase in white blood cell count and neutrophils. Anorectal examination must be performed under strict aseptic conditions using fingers with gloves to examine the anal and rectal areas. The finger should enter the anus gently, and the patient is instructed to contract the anal sphincter to determine if there is a rupture of the anal sphincter muscles. If there is a rupture, the anus will lose tension and become relaxed; if only partially torn, there will still be a sense of tension in the sphincter muscles. The examination can also determine if there is a perforation in the lower rectum, which can be judged from the examiner's sensation. If the intestinal wall is smooth, there is no injury; if there is a perforation, there will be local pain and a feeling of emptiness.

　　Diet has little significance for the relief of symptoms in patients with anal canal injury, and it is recommended to eat more vegetables and fruits, drink Huaiju drink regularly, and prevent constipation of feces. The rest of the dietary requirements should be based on the specific symptoms of the patient, and it is necessary to consult a doctor for specific dietary standards tailored to the disease.

　　Anal canal injury is mostly caused by trauma or surgical injury, and the treatment should pay attention to the distinction between early and late stages.

　　1. Early treatment

　　(1) Debridement and drainage: When debriding the local anal injury, it is necessary to cherish the tissue, try to preserve the tissue, align it, and suture it to prevent malunion; except for one断裂, the anal canal sphincter muscle should be sutured and not excised. First, perform a horizontal double-layer suture after local debridement, and place a smoke tube drain in front of the sacrum around the anal canal.

　　(2) Proximal ostomy: To prevent local infection after anal and anal canal repair, a sigmoid colon ostomy is performed at its proximal end. This allows the repaired area to rest sufficiently and heal smoothly. The distal sigmoid colon and rectum should be thoroughly flushed with normal saline, and washed with neomycin and metronidazole solution.

　　(3) Prevention and treatment of infection: Third-generation cephalosporins such as cefoperazone (Xianfengbi) or ceftriaxone (Ganbizhi) and metronidazole, etc., should be used for prevention and treatment of infection before, during, and after surgery.

　　2. Late treatment

　　In the late stage of anal canal injury, due to scar deformity, the anal canal will become narrow and incontinent, seriously affecting the quality of life of the patient. Therefore, in the late stage, the treatment is mainly aimed at anal canal stenosis and incontinence.

　　(1) Treatment of anal canal stenosis: The incidence of severe scar deformity or extensive stenosis after anal canal injury can be as high as 32.8%. The treatment of fibrous stenosis usually needs to be carried out 3-6 months after the trauma has healed and the perianal tissue inflammation has subsided.

　　① Anal Canal Dilatation: For mild anal canal stenosis, hard rubber tubes or metal dilators are mainly used for repeated expansion of the stenotic part, gradually increasing the diameter of the dilator until it can pass through the operator's little finger. The expansion should be gentle to avoid causing further tearing and exacerbating the scar stenosis. The initial expansion is once a day, and after normal defecation, it is changed to 1-3 times a week, continuing for half a year.

　　② Anal Canal Stenosis Incision: For severe stenosis with poor expansion effect, anal canal stenosis incision can be performed. The patient is placed in the lithotomy position, and a longitudinal incision is made from the anal opening to the coccyx. The stenotic scar tissue at the posterior commissure of the anal opening is incised, starting from the dentate line to 5cm behind the anal opening. The incision is fully exposed, and the external sphincter muscle is checked, especially the subcutaneous part. If fibrosis is present, the part of the sphincter muscle should be incised. Use several mosquito forceps to clamp the edge of the normal rectal mucosa 2cm, and then use a small curved scissors to free 1cm. Carefully pull the freed rectal mucosa and suture its edge intermittently to the subcutaneous tissue at the anal opening (excluding muscle tissue). For patients with severe anal stenosis, after excising the scar, the rectum can be pulled down, which can restore the function of part of the injured rectum.

　　(2) Treatment of Anal Incontinence: Traumatic anal incontinence is mostly due to anal sphincter rupture injury during war, while in peacetime, it is due to the over-expansion of the anal sphincter leading to weak anal closure, without the anal sphincter itself being ruptured, which is called anal sphincter relaxation.

　　① Anal Sphincter Rupture Repair Method: The ends of the anal sphincter are determined by palpation, and radiating incisions are made on both sides of the scar tissue. The broken ends of the muscles are freed, the incisions are deepened, and the scar tissue is removed. A part of the rectal wall is freed, and a small amount of fibrous tissue is retained at the ends of the muscles to provide a solid base for suture. The ends of the anal sphincter are sutured in an '8' shape, and after trimming the skin edges, a loose suture or an open suture is left. For severe incontinence, one or both sides of the adductor magnus muscle can be used to replace the anal sphincter's sphincteric function.

　　② Anal Sphincter Relaxation Method: A semi-circular incision is made 3.7 to 4.0 cm in front of the anus, and the concave surface is exactly opposite the posterior part of the anus. The skin flap is separated to expose the superficial part of the external anal sphincter, and the two outer edges of the exposed external anal sphincter are sutured together in an interrupted manner to make the anus just big enough to accommodate one finger. The skin flap is sutured in an interrupted manner, and a rubber sheet is placed under the skin for drainage, and the dressing is lightly compressed.

　　③ Anal Sphincter Stimulation Method: In recent years, the continuous electrical stimulation of pelvic floor and perineal muscles has achieved certain effects in the treatment of anal incontinence caused by anal, rectal trauma or infection. This method can be used when the pelvic floor muscles are intact, without infection and severe perianal scars, and the anal sphincter and levator ani muscles do not have severe fibrosis. There are two types of devices: A. Implantable device: two electrodes are placed in the pelvic floor muscle area through an incision in the perineum, and the wire is connected to an electronic device under the fascia of the rectus abdominis. The disadvantage is that there may be a foreign body reaction, tissue damage, and infection. B. Anal plug device: two dumbbell-shaped stainless steel ring electrodes are inserted into the anus, and connected to the stimulator through a wire. This method is convenient to use, and through the exercise of the striated muscles by electrical stimulation, the function of the weak muscles can be restored.