Congenital anorectal stenosis

　　The occurrence of congenital rectal and anal stenosis is the result of malformation during embryonic development, with males and females being basically the same, with only anatomical differences. The disease is also a result of the process of septation of the cloaca, where the urogenital sinus communicates with the anal-rectal sinus, forming high or intermediate position anomalies, resulting in various incomplete anal-rectal developments and fistulas between the rectum and the urethra or vagina. The obstruction in the posterior movement of the anus and the incomplete development of the perineum can lead to this result, forming low position anomalies, such as anal skin fistula, anal vestibular fistula, and anal stenosis.

　　1. Sudden onset of intermittent abdominal pain, with severe cramping pain in mechanical intestinal obstruction. Children have thin abdominal walls, and during abdominal pain, the protruding intestinal shape and peristaltic waves can often be seen. In paralytic intestinal obstruction, there is no cramping pain, only persistent distension pain may occur when there is severe distension, and neither the intestinal shape nor bowel sounds can be seen..

　　2. Vomiting, abdominal distension; if the obstruction site is high, vomiting occurs early and frequently, vomiting gastric juice and yellow bile, with only upper abdominal distension or no distension. If the obstruction site is low, vomiting occurs late, vomiting fecal-like fluid, and abdominal distension is obvious. In the early stage of paralytic intestinal obstruction, vomiting is usually not present, and late vomiting can contain fecal-like material, with significant abdominal distension.

　　3. The absence of defecation and排气 is a sign of complete intestinal obstruction, but in the early stage of obstruction, the feces and gas in the distal intestinal tract can still be excreted, and it should not be mistaken that there is no obstruction. In intestinal strangulation, blood-stained fluid may be excreted. In addition to the above symptoms, there are systemic toxic symptoms, such as drowsiness, pallor, dehydration, and others. Generally, intestinal gangrene can occur within 6-8 hours of intestinal strangulation, often accompanied by toxic shock, and the condition is extremely dangerous.

　　A diagnosis can be made by combining a history of difficult defecation with local examination. In cases where it is difficult to judge the stenotic segment, barium enema radiography can help confirm the diagnosis.

　　The manifestations vary due to different degrees of stenosis. Severe stenosis can cause difficulty in defecation at birth, manifested by straining during defecation, crying, and may appear low intestinal obstruction signs from several days to several months. Mild stenosis can normally excrete soft stool, but it may be difficult to defecate when the stool is formed, with thin, string-like stool, chronic constipation, and even fecal impaction. There are also cases where individuals seek medical attention only after long-term difficulty in defecation. Chronic difficulty in defecation can lead to gradual expansion of the proximal colon and rectum, resulting in secondary megacolon and megarectum. Locally, the anal orifice may be narrow, even with only a small hole, where even a catheter cannot be inserted. High mid-level stenosis may have a normal anal appearance, but the fifth finger cannot pass through the stenotic segment during palpation.

　　The etiology of this congenital malformation is unclear and may be related to environmental factors, genetic factors, dietary factors, and emotional and nutritional conditions during pregnancy. Therefore, it is impossible to prevent the disease directly. Early detection, early diagnosis, and early treatment are of great significance in preventing the disease. Regular checks during pregnancy should be carried out, and if the child shows a tendency of abnormal development, timely examination should be conducted to clarify the situation.

　　Congenital rectal anal atresia, as a surface deformity, is easy to diagnose. In addition to clinical examination, it is necessary to further measure the distance from the rectal blind end to the levator ani plane and the anal skin to determine the type of deformity, the location of the fistula, and associated deformities. The specific methods of these examinations are as follows:

　　1, Peripheral blood

　　When there are symptoms of infection and systemic toxicity, peripheral blood white blood cells and neutrophils increase, and there may be a decrease in platelet count and other manifestations.

　　2, Blood biochemistry

　　When complications such as dehydration and acidosis occur, routine blood tests for sodium, potassium, chloride, calcium, blood pH value, blood urea nitrogen, and creatinine are performed.

　　3, Urinalysis

　　The child's urine contains meconium components.

　　4, Inverted lateral X-ray film

　 　It is required to take films more than 12 hours after birth, waiting for the gas to reach the rectum. Children with poor vitality may need more time. Barium is applied to the skin in the perineal anal area as a marker, and the baby is inverted for 2-3 minutes before filming to make the meconium in the rectal blind end and the intestinal gas exchange, take the hip joint in a 90° flexion position, so that the angle between the P point (pubic center), C point (sacral coccygeal joint), and I point (ischial lowest point) can be fully displayed. The center is the greater trochanter of the femur, one film is taken at the time of expiration, inspiration, and crying. A line parallel to the PC line is set through the I point, and the distance between the PC line and the I line is the levator ani muscle group. The rectal blind end is above the PC line as high, between the two lines as intermediate, and beyond the I line as low. Or set the M point, that is, the intersection of the upper 2/3 and lower 1/3 of the ischial tuberosity. Those above the M line are intermediate, and those below the M line are low. However, attention must be paid to various influencing factors, such as insufficient intestinal gas, very sticky meconium, levator muscle movement, and X-ray projection angle deviation, which can all affect the accuracy of the position.

　　5, Fistulography

　　The的要求 is to show the image of the colon at the time of contrast agent injection and the image of the rectal fistula at the time of contrast agent excretion. Double-contrast colonoscopy can show the relationship between the rectal fistula and the urethra, and vaginal contrast can show the relationship between the vagina and the rectum.

　　6, CT

　 　It can show the development status and direction of the levator ani muscle group, and can also be used as a reference for postoperative follow-up. In normal children, CT shows the puborectalis muscle as a soft tissue mass, fixed in front of the pubis, connected to the sides and posterior wall of the rectum, and the external and internal anal sphincters form an oval mass, which is difficult to separate. Children with different types of anal-rectal malformations have different CT findings, such as rectourethral fistula, the puborectalis muscle surrounds the urethra and rectal blind end, and the anal sphincter is located directly below the perineum.

　　7, B-ultrasound examination

　　It is not limited by time, no special preparation is required before the examination, the method is safe and simple, the measured data is reliable, the error is smaller than X-ray, it can be repeated, and the pain to the child is minimal.

　　8, Magnetic Resonance Imaging (MRI)

　　The application of this method in anal-rectal malformations can observe the changes of the anal and rectal muscle groups around, and at the same time, it can judge the type of malformation and whether there is a malformation of the sacrum and coccyx.

　　Patients with congenital anal-rectal malformations should have a light diet, avoid eating greasy, cold, and hard foods, eat more vegetables and fruits to prevent constipation. Patients should eat foods high in collagen, zinc, and diuretics. It is forbidden to eat hot, dry, and spicy foods that irritate the stomach.

　　1. Anal Dilation:Indicated for mild anal rectal stenosis and various anal shaping operations. Lying on the side or in the lithotomy position, a special metal probe (Hegar probe) is used, or a steel pen rod with a suitable curved shape and size, coated with lubricant, is inserted slowly into the rectum through the anus. Initially, once a day, for 15-29 minutes each time, and then gradually changed to every other day or twice a week according to the improvement of defecation difficulties, generally lasting for about 6 months. The probe is gradually increased from small to large until the stenotic segment can pass through the index finger smoothly, defecation is unobstructed, and recurrence is prevented. It is important to teach the parents of the children how to operate themselves, regularly review and consult at the hospital, and follow the doctor's instructions, which is crucial for long-term care. If the anal dilation still cannot maintain normal defecation, it is necessary to choose other surgical treatment methods in a timely manner.

　　2. Septum Resection:Remove the stenotic septum ring, retain the anal margin skin flap appropriately, slightly mobilize the anal canal skin, and then cross-suture with the anal margin skin flap to make the incision after suturing star-shaped, preventing the narrowing of the healing scar.

　　3. Longitudinal Incision and Cross Suture Technique:A longitudinal incision is made in the skin and subcutaneous tissue behind the anus, extending from the upper edge of the stenotic segment to 1 cm outside the anal margin. The anal canal is expanded so that the index finger can pass through, and the subcutaneous tissue around the incision is mobilized. The rectal mucosa on the posterior wall is sutured horizontally to the anal canal skin.

　　4. Anal Canal Y-V Flap Formation:A reverse Y-shaped incision is made on the posterior side of the perianal area, with the center located at the anal margin. The incision inside the anal canal needs to exceed the stenotic segment, and the incision outside the anal margin is about 2 cm long, with an angle of 90-100 degrees. The anal canal is expanded to accommodate the index finger, and the external triangular skin flap is fully mobilized and moved into the anal canal for matching and suture. After suturing, the incision presents a reverse V-shape.

　　5. Stenosis Dilation:Through the anal exposure of the anal canal and rectal junction, a longitudinal incision is usually made on the posterior side of the ring. The fibrous ring is cut to expand the anal canal narrow area so that the index finger can pass through, then slightly mobilize the rectal mucosa, and suture the upper and lower mucosa across the incision. If the degree of stenosis is severe, additional incisions can be made on both sides of the ring to facilitate relaxation.