Pediatric Meckel diverticulum

　　First, Etiology

     1. During embryonic development, the primitive midgut communicates with the yolk sac through the vitelline duct. By the end of the fifth week of gestation, the placental blood circulation has formed, and the yolk sac is no longer needed. Therefore, the intracorporeal part of the vitelline duct begins to narrow, gradually close, atrophy into a cord, and then be absorbed. Developmental abnormalities in the vitelline duct can cause various types of abnormality, including umbilical enteric fistula, umbilical sinus, umbilical flesh, vitelline duct cyst, Meckel diverticulum, and umbilical enteric cord.

　　2. The vitelline duct starts from the umbilical end and atrophies and regresses towards the intestinal end. If the umbilical end has regressed but the intestinal end has not, a blind sac is formed, known as the distal ileal diverticulum. In 1809, Meckel (Meckel) made a detailed description of this congenital anomaly in embryology and clinical aspects, hence the name Meckel diverticulum.

　　Second, Pathogenesis

　　1. The diverticulum is generally located on the opposite side of the mesentery of the ileum, 20-100 cm from the ileocecal valve, 2-5 cm long, with an independent blood supply and mesentery. The apex of the diverticulum is often free in the abdominal cavity, and it can also have residual cords connected to the umbilicus. The loops of the intestines can twist around the cords or be compressed by the cords, causing intestinal obstruction. The apex of the diverticulum can also adhere to other intestinal loops, causing intestinal obstruction. Sometimes, the inversion of the diverticulum can be the starting point of intussusception, causing intussusception.

　　2. The wall of the diverticulum contains three layers, namely the serosa, muscular layer, and mucosa. The mucosa is usually ileal mucosa, with about 50% containing ectopic tissues such as gastric mucosa and pancreatic tissue, with the gastric mucosa being the most common. These tissues can secrete hydrochloric acid and digestive enzymes, which can corrode the diverticulum and its surrounding tissues, causing ulcer hemorrhage and perforation.

　　3. The diverticulum can also become obstructed, develop acute inflammation, necrosis, and perforation due to its own torsion, the entry of worms or foreign objects.

　　Meckel diverticulum can also be accompanied by other malformations, such as umbilical hernia, malrotation of the intestines, intestinal atresia, intestinal duplication anomaly, and congenital heart disease, with a reported incidence of up to 8.4%. Literature reports that complications occur in 15% to 30% of cases, which can occur at any age, with half occurring before the age of 10. Common complications include intestinal obstruction, diverticular ulcer hemorrhage, diverticulitis or perforation, and diverticular hernia.

　　1. Intestinal obstruction

　　In a comprehensive report of 83 cases of pediatric Meckel diverticulum by the Comprehensive Hospital of China Medical University, 29 cases had intestinal obstruction without intestinal necrosis due to diverticular adhesion, and 8 cases had intestinal necrosis. There were 8 cases of acute intussusception and 1 case of chronic intussusception caused by the diverticulum, a total of 46 cases (55.4%). Recently, our hospital encountered a newborn with an abdominal hernia strangulation, intestinal obstruction, peritonitis, and intestinal perforation due to Meckel diverticulum and a band embedded in the intestinal tract. Emergency surgery was performed to remove the necrotic intestinal tract and diverticulum and cure the condition. Generally, it is reported that 25% to 54% of Meckel diverticula cause intestinal obstruction, and the intestinal obstruction caused by the diverticulum is mainly low and often strangulating, and it is difficult to distinguish from small bowel obstruction caused by other adhesion bands. Intussusception caused by the diverticulum as the starting point of inversion can only be determined during surgery or when examining pathological specimens after surgery. The main manifestations of low intestinal obstruction caused by Meckel diverticulum include: paroxysmal crying or abdominal pain, accompanied by nausea, vomiting, and even fever. After abdominal pain, defecation and flatus decrease or stop. In cases with intussusception, there may be jam-like stools, palpable sausagelike mass in the abdomen, accompanied by periumbilical tenderness. If accompanied by intestinal torsion or strangulated intestinal obstruction, the condition will deteriorate rapidly, with obvious edema and electrolyte disorder, and in severe cases, shock and peritonitis may occur.

　　2. Diverticular ulcer hemorrhage

　　Due to the ectopic gastric mucosa in the diverticulum, its glands are gastric fundus glands, and there are also pyloric glands. The gastric fundus glands consist of parietal cells that secrete hydrochloric acid, chief cells that secrete digestive enzymes, and mucosal cells. The pyloric glands consist of mucosal cells and 'CT' cells, which can secrete gastrin. The hydrochloric acid secreted by the gastric fundus glands in the ectopic gastric mucosa of the diverticulum and the gastrin secreted by the 'CT' cells in the pyloric glands stimulate the parietal cells to secrete a large amount of hydrochloric acid, eroding the mucosa and blood vessels of the diverticulum, which can cause mucosal erosion and peptic ulcers. The result can lead to bleeding and diverticular perforation. In cases of Meckel diverticulum causing hematochezia, the detection rate of ectopic mucosa is as high as 81% to 100%, and the incidence of ulcer bleeding accounts for about 30%, up to 70%, and is more common in infants and young children. Generally, there are no prodromal symptoms, such as gastrointestinal symptoms such as vomiting. Generally, it appears suddenly as painless, whole blood stools, with a large amount of blood, accompanied or not accompanied by abdominal pain. Initially, the stools are dark purple or dark brown, mixed with fecal matter; when there is a large amount of bleeding, the stools are dark red or bright red, and there may be 3 to 5 times within a day and night, lasting for 2 to 3 days. The child quickly shows pale complexion, thirst, restlessness, listlessness, fine and rapid pulse, cold limbs, less urine, and other symptoms of hemorrhagic shock. However, at this time, there are very few abdominal signs, occasional mild tenderness, and most children can temporarily stop bleeding after receiving blood transfusion and other supportive therapies. However, after some time, bleeding recurs. If bleeding does not stop, children may develop anemia. In the data we collected, 25% of diverticular hemorrhage cases were found.

　　3. Diverticulitis or perforation

　　The Comprehensive Report of China Medical University has 2 cases with diverticulitis without necrosis, 6 cases with necrosis, 17 cases with diverticulitis complicated with perforation and peritonitis, a total of 25 cases (30.1%), most of which have necrosis and perforation (23/25), accounting for 92%. It is generally believed that diverticulitis is caused by foreign bodies in the diverticulum. The clinical manifestations of acute diverticulitis are difficult to distinguish from acute appendicitis. Right lower abdominal pain appears at the onset of the disease, usually persistent abdominal pain without a history of转移性 right lower abdominal pain. The muscle tension and tenderness are closer to the right umbilical side, higher and more inward than the general appendix. It often accompanied by diarrhea or hematochezia. The tenderness of the rectal wall on the right side is not obvious. In cases of diverticulitis complicated with perforation, peritonitis can occur, accounting for 90% in this group, and 55% (Cobb) according to some reports. At this time, the child may have severe abdominal pain, vomiting, fever, elevated white blood cell count, obvious peritoneal irritation signs in the abdomen, which may appear pneumoperitoneum, generalized abdominal tenderness, marked abdominal muscle tension, disappearance of lung liver dullness, weakened or increased bowel sounds, and may also appear symptoms of small bowel obstruction, which are due to adhesive intestinal obstruction or inflammatory intestinal paralysis caused by diverticulitis. Occasionally, there may be a history of hematochezia before perforation, and clinical diagnosis is often made as appendiceal perforation and peritonitis, followed by surgical treatment.

　　4. Other

　　Meckel diverticulum can enter the inguinal, femoral, or umbilical hernia sac, with the right side more than the left, and more in males than in females. It is common for the diverticulum to herniate into the inguinal hernia sac, known as diverticular hernia. Meckel diverticulum can be completely incarcerated in the hernia sac, making diagnosis extremely difficult and easily misdiagnosed, leading to delayed treatment. Clinical symptoms include most patients reporting sensitivity in the inguinal area, but without tenderness. Some may have abdominal cramps, presenting as incomplete intestinal obstruction. During examination, another conical object parallel to the spermatic cord can be found in the inguinal area, with marked tenderness and palpation. At this time, suspicion of diverticular hernia arises, and timely diagnosis and treatment should be sought. Preoperative diagnosis of Meckel diverticulum is difficult, so when there is inflammation in the lower right abdomen, low intestinal obstruction, and lower gastrointestinal bleeding (especially with a history of recurrence 2-3 times), the possibility of diverticular complications should be considered. To diagnose the cause of gastrointestinal bleeding, technetium-99m scanning can be used. For those with ectopic gastric mucosa in Meckel diverticulum, a radioactive accumulation area can be displayed in the middle abdomen near the right lower abdomen or near the umbilicus. When non-surgical treatment is ineffective for the above complications, surgical treatment is required. If the lesion is found to be inconsistent with the original diagnosis during surgery, a careful examination of the ileocecal junction 100 cm from the ileocecal junction is necessary to determine whether it is caused by diverticulum.

　　2. Pregnant women should try to avoid harmful factors including staying away from smoke, alcohol, drugs, radiation, pesticides, noise, volatile harmful gases, and toxic and harmful heavy metals. During the process of prenatal care during pregnancy, systematic screening for birth defects should be carried out, including regular ultrasound examination, serological screening, and if necessary, chromosomal examination to take practical and feasible diagnostic and treatment measures.

　　1. Pre-marital physical examination plays a positive role in preventing birth defects, the size of which depends on the examination items and content. It mainly includes serological tests (such as hepatitis B virus, syphilis spirochete, HIV), reproductive system examination (such as screening for cervical inflammation), general physical examination (such as blood pressure, electrocardiogram), and inquiries about family history of diseases and personal medical history. Good genetic counseling work should be done.

　　1. Routine blood tests and blood biochemical tests should be performed:Inflammation can significantly increase white blood cells and neutrophils; anemia can lead to a decrease in hemoglobin and red blood cells; in severe cases, there may be a decrease in platelets, and blood biochemical tests may show increased creatinine and urea nitrogen. There may be water and electrolyte imbalances, and blood sodium, potassium, calcium, and blood pH should be checked. Routine stool examination can detect hematochezia and positive occult blood in stool.

　　2. X-ray examination:Abdominal X-ray can only detect changes in intestinal obstruction, and if there is diverticular perforation, free gas may be present under the diaphragm. Barium enema examination can exclude changes such as colon polyps and hemangiomas.

　　3. 99mTc scan examination:Due to the special affinity of 99mTc for the gastric mucosal wall cells, it can be absorbed by the gastric mucosa, forming a radioactive accumulation area locally, with a diagnostic accuracy of up to 90% or more. Most of this radionuclide is accumulated, utilized, and excreted through the gastric mucosa. The diverticula with bleeding often have ectopic gastric mucosa, and 1-3 mCi of 99mTcO4- can be injected intravenously. Scans are performed every 15 minutes, and continuous observation is conducted for 1-3 hours. Abnormal radioactive accumulation areas in the abdomen can help with diagnosis. Zhou Yiming et al. performed 99mTcO4-γ imaging on 13 patients with hematochezia, 11 of whom were positive and received preoperative diagnosis, with a diagnosis rate of 84.6%. For patients with negative findings, a repeat photograph can be taken after subcutaneous injection of pentagastrin to improve the diagnostic rate. Zhang Changbao et al. photographed 2 children with intermittent hematochezia who showed no abnormal radioactive accumulation in the abdominal γ-photography, and the diagnosis was confirmed after injection of pentagastrin. This change was also observed in intestinal duplication malformation with gastrointestinal bleeding, and it was confirmed by surgery and pathology. This change also occurs in intestinal duplication malformation with gastrointestinal bleeding. It is too late to perform this examination for children who have already developed acute abdominal symptoms, and it is not helpful for diagnosis.

　　The diet for pediatric Meckel diverticulum should be light and nutritious, with an emphasis on eating foods rich in vitamins such as fruits, apples, peaches, bananas, pears, cherries, oranges, and more lean meat to enhance physical fitness. Try to eat less spicy and刺激性 foods. For example: onions, pepper, chili, Sichuan pepper, mustard greens, fennel. Quit smoking and drinking, as well as stimulants such as coffee.

　　First, preoperative preparation

　　In the treatment of complications of Meckel's diverticulum, water and electrolyte imbalances and blood volume and platelet reduction often occur due to intestinal obstruction and ulcer bleeding. Diverticulitis or perforation can cause peritonitis, leading to severe infection. Therefore, preoperative preparation should be made according to the patient's condition to ensure that the child receives the best surgical treatment, resecting the diverticulum to achieve a good therapeutic effect.

　　1. Ulcer bleeding: Preoperative blood transfusion is extremely important to quickly correct hemorrhagic shock, supplement sufficient blood volume, and restore hemoglobin to above 9g, systolic blood pressure to above 10.7kPa (80mmHg). Generally, preparation is needed for 6-12 hours to ensure that the child has sufficient blood volume to prevent hypoxia under anesthesia and prevent shock.

　　2. Diverticulum causing intestinal obstruction: When the child arrives at the hospital, immediate blood gas analysis should be performed to observe for imbalances in water and electrolytes, and timely correction should be made. In severe cases, plasma or whole blood transfusion should be given. Generally, preparation should be made for 4-6 hours, and in cases of strangulated obstruction, surgery should be performed as soon as possible. In cases of abdominal distension and peritonitis, gastroenteric decompression should be given. In cases of high fever and toxic symptoms, physical cooling and artificial hibernation mixture should be given. At the same time, broad-spectrum antibiotics should be used.

　　3. Diverticulitis or perforation: Preoperative preparation should be made according to appendicitis or peritonitis.

　　Second, surgical treatment

　　During surgery, based on the shape, size, pathological changes, and attachment of the ileum of Meckel's diverticulum, resection of the diverticulum or partial ileum resection can be performed. Common surgical methods include the following:

　　1. Simple ligation, excision, and purse-string suture method: This method is used for diverticula similar in size to the appendix and with a base not exceeding 1cm.

　　2. Oblique resection: As shown in Figure 3, the lesion is limited to the diverticulum, and the base is wide without inflammation. To avoid intestinal stricture after resection, the base is clamped obliquely at a 45° angle between the bottom of the diverticulum and the longitudinal axis of the ileum with two straight vascular forceps, and then the diverticulum is resected. After disinfection, the intestinal cavity is not opened, and the “U”-shaped interlocked full-thickness and muscularis mucosae suture is performed.

　　4. Resection of diverticulum and adjacent ileum: This procedure is suitable for patients with intestinal necrosis caused by intussusception due to diverticulum. Intestinal necrosis caused by internal hernia, volvulus, or twisted bands; diverticular base perforation with significant inflammatory infiltration; diverticular base abnormally wide or with significant ectopic tissue, along with resection of the ileum and anastomosis.