Congenital duodenal atresia

　　One, Etiology

　　The normal intestinal development process is divided into three stages: ① The lumen开通 stage, in the early stage of embryo, the small intestine has formed a贯通 intestinal tract. ② The stage of epithelial cell proliferation, in the 5th to 10th week of embryo, the epithelial cells proliferate and reproduce, causing the lumen to be blocked, forming a temporary filling period. ③ The re-formation of the lumen stage, completed in the 11th to 12th week of embryo, in which many cavities appear in the blocked intestinal tract, merging with each other, making the lumen communicate again. If the development of the embryo's intestinal tract is obstructed in the second or third month, a segment does not appear a cavity, stays in the solid phase, or appears a cavity but does not merge with each other, or merge incompletely, it will form intestinal atresia or stenosis. Some people believe that intestinal circulation disorders in the fetal period can also cause atresia, such as the rapid contraction of the umbilical ring, the gastrointestinal tract being straight tube-like before 8 weeks of embryo, and then the rapid development of the intestine and slow expansion of the abdominal cavity, causing the small intestine to become curved, the abdominal cavity can not accommodate it, protruding into the umbilical vesicle, 10 to 12 weeks the abdominal cavity increases, the protruding mesentery rotates counterclockwise and returns to the abdominal cavity, and before returning the umbilical ring contracts, affecting the blood circulation of this segment of the small intestine, causing atrophy, and developing into stenosis or atresia. If the small intestine's nutritional blood vessels are abnormal, have defects or branched malformations, or occur intussusception, they can also lead to maldevelopment.

　　Two, Pathogenesis

　　1. Common locations Congenital duodenal atresia can occur at any part of the duodenum, but it is most common near the common bile duct, pancreatic duct, and ampulla, and the lesion is mostly located in the ampulla of the second segment of the duodenum. It is generally believed that the lesions distal to the ampulla are more common than those proximal to it.

　　2. Pathological types Congenital duodenal atresia is commonly seen in 4 types:

　　(1) Blind tube type: The proximal end of the duodenum terminates in an abnormally dilated blind tube, the distal end is small and separated from the proximal end, and the continuity of the intestinal tract is lost.

　　(2) Band type: Both the proximal and distal ends of the duodenum are blind-closed, and they are connected by a fibrous band, and this type is the rarest.

　　(3) Blind sac type: Although the proximal and distal ends of the duodenum are connected, there is a blind sac formation in the middle, the lumen is blocked, and there is a significant difference in diameter between the proximal and distal ends.

　　(4) Membranous type: This type is the most common, accounting for 85% to 90% of duodenal atresia. Its characteristic is that the intestinal tract maintains continuity, but there is a septum in the lumen of the second or third segment of the intestine, resembling a web, which can be a single septum or a multiple septum, most of which are located near the Vater's papilla, causing varying degrees of duodenal obstruction. There is a small hole in the center or edge of the septum, with a diameter as thick as a probe, making it difficult for food to pass through. The septum without a hole will cause obstruction at birth, while the septum with a large hole may be asymptomatic or have mild symptoms. Krieg (1937) collected 21 cases of congenital duodenal septum and statistically analyzed the relationship between the presence or absence, size, and onset time of the septum hole, indicating that the larger the hole of the septum, the later the symptoms appear. Some symptoms appear only in childhood or adulthood. Although anatomically it is incomplete obstruction, in terms of function, it is actually equivalent to atresia; sometimes the septum is complete, and it is also atresia anatomically, and in some cases, the septum can prolapse into the third segment.

　　3, Pathological changes in the atresia type cause complete obstruction, with dilation of the duodenum and stomach at the proximal end of the obstruction, which can be several times wider than the normal diameter. The intestinal wall thickens, and peristalsis diminishes; the distal duodenum at the site of obstruction is atrophic and small, in cases of complete atresia, there is no gas in the lumen, which is thinner than a chopstick, and the wall is very thin. If it is a type with a孔 septum, it causes incomplete obstruction, and the proximal intestinal tract is thickened, the degree of dilation is related to the degree of stenosis of the intestinal lumen and the duration of the disease.

　　1, Intrahepatic bile duct dilatation:With the increase in the number of surviving cases, the number of cases with intrapulmonary bile duct cystic dilatation also increases. Clinical manifestations include fever, jaundice, and whitish stools. Diagnosis can be made by B-ultrasound and CT.

　　It is divided into three types: solitary cystic cavity with no communication with surrounding structures belongs to type A, solitary cyst with communication with surrounding structures belongs to type B, and multiple cystic dilatation belongs to type C. Types A and B can be cured by percutaneous cyst puncture and drainage under B-ultrasound or intracorporeal cyst jejunal anastomosis, while type C has poor treatment effects, and liver transplantation should be considered.

　　2, Postoperative cholangitis:Cholangitis occurring within one month after surgery is called early cholangitis and poses the greatest harm. Because at this time, the bile duct epithelium has not healed with the intestinal mucosal epithelium, and the originally open bile ducts are prone to occlusion after inflammation. The child may present with restlessness for no apparent reason, refusal to eat, abdominal distension, reduced bile output, pale stools, fever, worsening jaundice, and increased white blood cells.

　　At this time, the dosage of hormones should be increased, and antibiotics should be changed. Recurrent cholangitis, when uncontrolled, often leads to death due to liver failure or sepsis. Cholangitis occurring more than 3 months to several years later is called late cholangitis, characterized by recurrent fever and jaundice, and severe cases may die due to liver failure. In such cases, early consideration should be given to liver transplantation.

　　3, Portal hypertension.

　　1, Excessive amniotic fluid during pregnancy: About 40-60% of mothers of infants with duodenal atresia have a history of polyhydramnios. Normally, amniotic fluid is swallowed by the fetus and absorbed at the distal end of the small intestine. Any obstruction in the intestines can lead to abnormal accumulation of amniotic fluid. The farther the obstruction, the less likely polyhydramnios, as there is sufficient gastrointestinal absorption of amniotic fluid and its excretion through the kidneys.

　　2, Neonatal vomiting: In the case of duodenal atresia, vomiting occurs soon after birth (within a few hours to 2 days), and it is frequent, large in volume, forceful, and sometimes喷射性. Since the obstruction is usually located at the distal end of the common bile duct and the ampulla of Vater, the vomitus often contains bile in addition to stomach contents and milk. In severe cases, blood or coffee-ground-like material may be mixed. The frequency and severity of vomiting progressively worsen.

　　16. 3. Abnormal defecation: Due to complete obstruction, the child does not have meconium excretion, and occasionally a few cases may have 1-2 times of small amounts of meconium. In cases where the atresia is located in the distal duodenum, the meconium is only composed of intestinal secretions, mixed with shed cells, or a small amount of greyish-white stool is excreted. This meconium is drier than normal, less in quantity, paler in color, and excreted at a later time.

　　15. 4. Abdominal distension: Abdominal distension in neonatal duodenal obstruction is not significant, most of them only have slight swelling in the central upper abdomen. The vomiting of the infant also relieves the pressure in the stomach, so there may be no abdominal distension at all. The peristaltic waves in the stomach are less common symptoms. In cases with concurrent intestinal perforation, abdominal distension is more obvious, and even the abdominal wall veins are clearly visible.

　　14. 5. General condition: In the early stage, the general condition is good, while in the late cases, many present with emaciation.

　　For pregnant women with polyhydramnios, one should be vigilant about the possibility of congenital malformation. The simultaneous elevation of amniocentesis, alpha-fetoprotein, and acetylcholinesterase levels can help in prenatal diagnosis.

　　10. Do not drink alcoholic beverages for a long time, quit the habit of smoking and drinking, do not overeat pickled vegetables, sour, spicy and刺激性 food, do not eat moldy food. It is more important for those with chronic pharyngitis to develop good dietary hygiene habits, such as eating less meat and more vegetables, eating more fresh fruits and vegetables, etc.

　　9. In cold seasons, maintain appropriate temperature and humidity indoors, pay attention to air circulation. The room temperature should be around 20℃, do not cover too many quilts during sleep at night, avoid too high temperature or excessive dryness, causing discomfort in the throat. Do not sleep with the wind, rest for a while after strenuous labor, do not take a cold shower immediately. For those with acute pharyngitis caused by common cold or flu, drink more hot water or ginger soup to induce sweating, increase urine excretion. Pay attention to smooth defecation. Treat acute inflammation in a timely manner to prevent it from developing into chronic. Organs with chronic lesions are more prone to malignancy.

　　8. Strengthen labor protection. For harmful gases, dust, such as silica dust, ammonia chloride, bromine, iodine, etc., in the production process, proper handling is required. Workers who have long-term contact with harmful chemical gases should wear anti-toxic masks and protective isolation clothing, etc.

　　7. Strengthen the body's constitution, enhance physical exercise. Commonly use cold water to wash face and body, prevent colds, work and rest in moderation, live in a regular manner, do outdoor activities in the morning or after work.

　　1. 'Amniotic fluid cytology examination:When the mother has polyhydramnios or when there is a high suspicion of fetal high obstruction in the ultrasound examination, amniocentesis can be performed to check the amniotic fluid cytology, to determine whether there is a chromosomal abnormality coexisting.

　　2. Farber test:Enema with 1% saline solution or 1% hydrogen peroxide solution, without the discharge of a large amount of meconium, can exclude constipation due to meconium and congenital megacolon. The examination of meconium shows no lanugo and keratinized epidermis, indicating that the meconium does not contain amniotic fluid content. Intestinal atresia has occurred during the fetal period. Combined with rectal examination, it can help in diagnosis.

　　3. Abdominal X-ray examination:Standing abdominal X-ray or iodine contrast examination can show an expanded air-fluid level in the first segment of the stomach and duodenum in duodenal atresia, that is, the typical 'double bubble sign', with no gas in other parts of the abdomen.

　　4. Ultrasound examination:In addition to clinical diagnosis, it can also be used for prenatal examination, especially the line array real-time ultrasound scan can show two typical fluid areas in the abdomen of the fetus with duodenal atresia, suggesting the diagnosis of the disease, for the correct diagnosis after birth and for the preparation of treatment.

　　5. Anal examination:Exclude the possibility of anal atresia.

　　It is recommended to eat light and nutritious liquid and semi-liquid foods. Eating foods rich in protein is beneficial for wound healing. Supplement various vitamins, eat more fresh vegetables and fruits. You can eat more lean meats, milk, eggs, and other foods rich in protein. It is best not to eat foods rich in protein, which are beneficial for wound healing. Supplement various vitamins, eat more fresh vegetables and fruits. You can eat more lean meats, milk, eggs, and other foods rich in protein.

　　One, treatment

　　1. Congenital duodenal atresia should be operated on immediately upon diagnosis. While preparing for surgery, actively correct dehydration, electrolyte and acid-base imbalance, and administer vitamin K and antibiotics.

　　2. For patients with proximal duodenal obstruction, a transverse incision above the umbilicus on the right side of the abdomen is used, which has good exposure of the surgical field and is convenient for a thorough exploration of the entire abdomen. The rectus muscle is cut with an electrosurgical knife, and after entering the abdominal cavity, the dilated duodenum is often exposed at the incision.

　　3. The causes of duodenal obstruction are different, and the surgical methods are also varied. Each etiology has a relatively fixed method. It is necessary to estimate whether there is a concomitant small bowel atresia, and complex atresia accounts for about 15%. During the surgical exploration, great attention should be paid to the presence of malrotation. If there is malrotation, it should be treated first before dealing with the abnormality of the duodenal lesion.

　　4. In patients with duodenal atresia, after entering the abdominal cavity, carefully examine the dilated duodenum. Check its activity. Push the hepatic flexure of the colon and the transverse colon to the left, fully exposing this area, and perform a duodenoduodenal side-to-side anastomosis or duodenojejunostomy. Carefully check the Ladd's bands during surgery to confirm that there is no crossing over the duodenum to avoid compression. The anastomosis should be at the lowest point of the duodenal obstruction, performing a full-thickness anastomosis. The incision on the proximal duodenum should be at least 2cm, and the small intestine or unused duodenum should be incised obliquely at the free margin of the mesentery. After the distal intestinal tract is incised, place a Foley catheter at the incision, inflate the balloon, and simultaneously inject normal saline into the distal small intestine. Observe whether the balloon can pass through the small intestine into the colon smoothly, or whether the normal saline can enter the colon smoothly, thus ensuring that there is no concurrent atresia elsewhere.

　　5. For patients with duodenal atresia, some surgeons have successfully performed duodenal-jejunal anastomosis behind the colon. In this case, the jejunum passes through the mesocolon for anastomosis. After anastomosis, the anastomotic site is placed below the mesocolon, and the mesocolon is attached to the duodenal tubular wall. Generally, 4-0 or 5-0 silk thread is used for full-thickness anastomosis. The knot can be tied inside or outside the lumen. Carefully suture the holes of the mesocolon, and the hepatic flexure of the colon can still be left in the left abdomen, while the small intestine is placed in the right abdomen.

　　6. For children with duodenal stenosis and diaphragm formation, before incising the proximal duodenum, it is necessary to perform a gastrostomy tube placement, with the catheter inserted into the distal intestinal lumen of the duodenum. If there is a diaphragm present, the catheter can cause folds when it is attached to it and suctioned. If there is a windbag-like diaphragm, the tip of the catheter can feel inserted further, but often there are folding phenomena at the attachment site of the windbag-like or diaphragm. When such a diaphragm exists, the incision should be made longitudinally from the proximal end to the possible attachment site of the diaphragm. Expand the incision beyond the attachment site of the diaphragm. At this time, one should be very careful and cautious because the Vater ampulla often accompanies these diaphragms. The diaphragm incision should be made in a radial manner to avoid injury to the ampulla. The Vater ampulla can be retained in the duodenal lumen in a lobular flap-like structure, and the duodenal incision can be closed laterally in the Heineke-Mikulicz manner.

　　2. Prognosis

　　There is evidence that the mortality rate of surgery is about 30%. Due to preoperative preparation and intravenous nutrition, the mortality rate has decreased to 5% to 10%. In the neonatal period, if Down syndrome is diagnosed, discuss with the patient's family to decide whether to perform surgery. Follow-up results have found that patients with duodenal atresia have a good quality of life after surgery, with only mild or no symptoms. However, there is research evidence that there may still be hypertrophic duodenal atresia and bile reflux gastritis. Despite these findings, patients are usually asymptomatic and do not require further treatment.