Meckel's diverticulum

Introduction to Meckel's Chamber The Meckelsdiverticulum is the distal ileum that is formed during the embryonic development and is degenerated by the yolk tube. Clinically asymptomatic, often diagnosed due to complications in the diverticulum. In 1808, Meckel first discovered that the diverticulum was derived from the remains of the yolk tube. In 1812 he gave a complete description of his embryology and clinical manifestations and complications, so the disease was named Meckel's diverticulum. The disease is occasionally complicated by other malformations, such as umbilical bulging, poor intestinal rotation, intestinal duplication, ectopic pancreas and congenital heart disease. Ehrensperger pointed out that the incidence of concomitant malformation can be as high as 8.4%. basic knowledge The proportion of illness: 0.002% Susceptible people: no specific population Mode of infection: non-infectious Complications: intestinal obstruction, intestinal torsion, adhesive intestinal obstruction, intussusception, peptic ulcer, peritonitis, edema

Meckel's diverticulum

(1) Causes of the disease

In the early stage of embryonic development, the endoderm cell population at the top of the yolk sac is involved in the embryonic body in the second week of normal embryo development, forming the original digestive tract, the front end is called the foregut, the tail is called the hindgut, and the middle part is called the midgut, the midgut and the yolk. The sacs communicate with each other, and there is a traffic pipe in the middle of the connection, which is called the yolk tube or the umbilical gut tube. In the normal development of the embryo, the yolk tube begins to occlude fibrosis on the 6th to 8th week, and then gradually shrinks to form a umbilical cord and midgut. The fiber cable belt gradually absorbs and degenerates from the umbilical end, and finally disappears completely. If an obstacle occurs during the process of absorption and degradation of the egg yolk tube, that is, the yolk tube absorption is degraded or not degraded, various types of yolk tube residual abnormalities will occur. Such as umbilical hernia, umbilical sinus, umbilical cord blood, yolk tube cyst and distal ileum diverticulum, when the umbilical end of the yolk tube has been absorbed and degraded, while the left yolk tube remains unclosed, the Michael's diverticulum is formed.

(two) pathogenesis

Most of the Merkel diverticulum is located on the ileal wall opposite the terminal mesenteric margin 10 to 100 cm from the ileocecal area. About 5% of the cases are open to the mesangial side of the intestine, due to the obstacles in the process of degeneration of the yolk tube. The location and extent of the diverticulum vary from site to site.

Yolk tube dysplasia (35%):

1 The blind end of the diverticulum is not connected to the intestinal wall and the umbilicus: the diverticulum is free in the abdominal cavity, 2 cm to 5 cm long, conical, tubular and spherical, and may have its own mesangial tissue or blood vessel on the opposite side of the mesentery. Diverticular mesangial band tissue; 2 diverticulum yolk tube failed to completely close: the umbilical end is open, and one end is connected with the narrow tube of the intestine, often with a small amount of intestinal fluid overflow, which is a yolk tube or umbilical hernia, a few of which are thicker, can be The umbilical part discharges the fecal-like substance, which stimulates the skin around the umbilical cord to cause erosion; 3 The umbilical end of the yolk tube is not completely absorbed and degraded: the diverticulum is connected with the umbilical cord with residual cord, which is called the umbilical yolk yolk duct diverticulum and umbilical sinus; 4 the yolk tube is completely blocked : However, a small amount of mucosal tissue remains in the umbilicus, forming a bright red polyp-like substance, often with a small amount of mucus-like secretions, called umbilical cord or umbilical polyps; 5 yolk tube cysts: the ends of the yolk tube are degenerate and occluded, while the middle of the tube Inflated expansion, and there are mucosal secretions forming capsules, called yolk tube cysts.

Other factors (27%):

The diverticulum has a separate mesangium, and the vasculature of the vasculature is formed between the diverticulum and the ileum. This mesangial has a chord-like connection and is clinically one of the causes of complications of intestinal obstruction.

The histological structure of the diverticulum is the same as that of the terminal ileum. It consists of mucosal layer, submucosa, muscular layer and serosal layer. The diameter of the diverticulum opening is generally smaller than that of the ileum. There are often superficial tissues in the wall of the diverticulum, mostly gastric mucosa, followed by Pancreatic tissue, duodenum and colonic mucosa, the mucosal tissue of the faint is different in the wall of the iliac crest, and the distribution of the gastric mucosa is wide. It can occupy most of the iliac wall, or it can be scattered in the island or in segments. Sexual distribution, if it is pancreatic tissue, mostly located at the top of the diverticulum, the yellow-white copper-like distribution under the serosa is observed by the naked eye, and the touch seems to have a hard tough feeling.

The presence of fascinating tissue in the iliac wall is another major cause of complications in Meckel's diverticulum. The fascinating gastric mucosa can cause diverticulum erosion, ulceration, hemorrhage and perforation. In the Merkel's diverticulum with complications, Gastric mucosa accounts for 28% to 61%. Morris reported 208 cases of Merkel's diverticulum, including 65 cases (28.5%) of ectopic gastric mucosa, and 72 cases of Merkel's diverticulum reported by Hunan Medical University (1997). There were 47 cases (65.3%) with ectopic tissue, including ectopic gastric mucosa, 36 cases, and 11 cases of ectopic pancreatic tissue.

Meckel's diverticulum prevention

1. Develop good habits, stop smoking and limit alcohol. Smoking, the World Health Organization predicts that if people no longer smoke, after five years, the world's cancer will be reduced by 1/3; secondly, no alcohol. Smoke and alcohol are extremely acidic and acidic substances. People who smoke and drink for a long time can easily lead to acidic body.

2. Don't eat too much salty and spicy food, do not eat food that is overheated, too cold, expired or deteriorated; those who are frail or have a certain genetic disease should eat some cancer-preventing foods and high alkali content as appropriate. Alkaline foods maintain a good mental state.

Merkel diverticulum complications Complications, intestinal obstruction, intestinal torsion, adhesive intestinal obstruction, intussusception, peptic ulcer, peritonitis, edema

Due to the differences in various types of diverticular morphological sites and pathological changes, clinically different surgical acute abdomen can be presented, which are summarized as follows:

1. Intestinal obstruction:

When the vasculature of the diverticulum or the inflammatory lesions of the diverticulum adheres to the tissues and organs of the abdominal cavity, a series of pathological changes can occur in the case of intestinal dysfunction, leading to various forms of intestinal intestinal obstruction.

(1) Intestinal torsion: Intestinal torsion occurs with the remaining ligament of the yolk tube fixed to the umbilicus and the diverticulum as the axis.

(2) diverticulum torsion: mostly diverted pear-shaped diverticulum, with the diverticulum neck as the axis torsion, and thus the continuous transit of the ileum.

(3) Adhesive intestinal obstruction: adhesion between the diverticulum and the surrounding intestinal or mesenteric can cause intestinal intestinal obstruction.

(4) internal hemorrhoids: the mesenteric cord is attached to the intestine or mesentery, so that some of the intestines are invaded between the intestinal cords, forming internal hemorrhoids, often causing strangulated intestinal obstruction.

(5) Intussusception: Due to the squatting of the sputum, it hinders the patency of the intestine, and forms an intussusception with the advancement of peristalsis.

(6) Diverticulum: The diverticulum enters the inguinal canal through the inner ring to form a special type of inguinal hernia, which is a litter box (Litter), which can be developed into a closed or twisted sputum.

(7) diverticulum prolapse: the diverticulum tube is wide, and the small intestines at both ends can be removed from the umbilicus to the intestinal obstruction through the diverticulum.

2. Diverticulum ulceration:

The gastric mucosa tissue in the diverticulum wall secretes gastric acid and gastric digestive enzymes. The exocrine secretion of the fascinated pancreatic tissue also has digestive enzymes. These digestive enzymes continuously act on the mucosa of the iliac wall, and the submucosal tissue produces peptic ulcer. The expansion is deep, causing the wall of the diverticulum to smash and invade the blood vessels and cause bleeding. This type of bleeding is often manifested as painless lower gastrointestinal bleeding.

3. Diverticulum Perforation Peritonitis :

This situation is also caused by the secretion of digestive enzymes in the gastric mucosa and pancreatic tissue of the sputum wall, which in turn affects the diverticulum wall, which leads to the perforation of the diverticulum, and the intestinal fluid flows into the abdominal cavity to change the peritonitis.

4. Diverticulitis :

Often due to indoor foreign bodies, parasites and other inflammation, mucosal edema, congestion, diverticulum stenosis affect the discharge of diverticulum content, the literature reported that there are hard crust shells in the diverticulum cavity, copper coins and necrotic aphids, leading to diverticulitis, On the basis of diverticulitis, further development of inflammation can also lead to perforation of peritonitis in the diverticulum.

Merkel diverticulum symptoms Common symptoms Acute abdomen right lower abdominal pain Abdominal pain Lower abdominal pain Peritonitis Nausea Low fever Low intestinal obstruction Intussusception Hemorrhage

When complications occur in the Merkel diverticulum, various acute abdomen manifestations may occur, and the complications are as follows:

1. Intestinal obstruction:

Merkel's diverticulum complications are common in low-grade small intestine obstruction. Domestic reports of intestinal obstruction account for 40% to 64% of complications, Ninov (1990) reported 64 cases, intestinal obstruction accounted for 65%, and Frank reported 34 cases of surgery. Intestinal obstruction accounts for 35%

(1) Intussusception: It is a common type of intestinal obstruction caused by Meckel's diverticulum. Because the diverticulum is mostly located at the end of the ileum, the diverticulum is conical, and the base is wider. When the intestinal dysfunction increases, the diverticulum can be turned over. Nested into the ileum cavity, becomes the starting point of intussusception, the diverticulum is turned into the intestinal lumen, the intestinal tube passes through the obstacle, and the peristaltic function is enhanced. The intestinal tube that is turned into the proximal diverticulum is stacked into the distal intestine to form the intestine intussusception. The intestine tube is further advanced and developed. When the ileocecal valve continues to enter the colon, a kinetic intussusception is formed. Sometimes the diverticulum does not turn into the ileum, and the intestine is inserted into the distal ileum to form an intussusception.

Meckel's diverticulum complicated with intussusception occurs mostly after early childhood, still with paroxysmal abdominal pain (paroxysmal crying), vomiting, jam-like bloody stool is a typical clinical manifestation, physical examination: abdomen carefully palpate more accessible sets The sausage-like mass of the overlapping part, the rectal examination is difficult to identify in addition to determining the rectal condition.

2. Diverticulitis :

Generally, the base of the Meckel's diverticulum is wide in the ileum, so that the secretion is easier to flow into the ileum and not accumulated in the sac. When the anatomy of the chamber is finger or gourd, the opening is narrow, or the diverticulum When the neck has obstruction, or there are foreign bodies and intestinal parasites, the clinical manifestations resemble acute appendicitis, most of which are appendicitis laparotomy. Frank reported 8 cases of diverticulitis were misdiagnosed as acute appendicitis before surgery, clinically due to diverticulum Complications and surgical resection of the diverticulum pathological results have diverticulitis changes, Ma Yong and other believe that Meckel's diverticulitis is the basis of various complications, Han Maozhen (1984) reported 50 cases of surgical complications, diverticulitis In 17 cases, the incidence of diverticulitis was also high.

Diverticulitis is more common in older children, acute, subacute attacks, often manifested as lower right abdominal pain, nausea, vomiting, low fever, abdominal palpation of the lower right abdomen near the umbilical tenderness, increased white blood cells, so clinically misdiagnosed acute appendicitis accepted Surgery, when the appendix is found to be normal and the clinical signs are heavier, the ileum end and ileocecal should be explored to avoid missing the disease, and then develop into a diverticulum necrosis, the serious consequences of perforation.

3. Merkel's diverticulum with umbilical hernia:

The disease is caused by the congenital yolk tube is not closed and the umbilical opening is open. The clinically chronic disease process, the umbilicus is generally a small amount of yellow, the odorous intestinal fluid overflows, and occasional gas is discharged, the disease should be removed from the fistula. Excision of the diverticulum should be differentiated from the urinary catheter before surgery: a suitable catheter can be inserted from the pupil, and 76% of the diatrizoate is injected for X-ray examination to confirm the diagnosis; or the methylene blue solution is injected from the bladder. Observe whether there is any overflow of methylene blue solution in the umbilicus.

4. Michael's chamber internal cavity foreign body insertion port :

Velanovich reported that a 9-year-old child who had eaten a coin was treated for a lower right abdomen. After examination, he found a foreign body coin in the digestive tract and observed the position for 2 days without surgery. The operation confirmed that the coin was embedded in the chamber. Similarly, the ingestion Hard shell peels and the like may also be embedded in the chamber and are not easily discharged and exhibit clinical symptoms.

5. Dysentery :

There have been no reports of malignant transformation of pediatric Merkel diverticula in the country. Moscs collected 1605 cases of Merkel diverticulum complications, 52 cases of diverticulum tumors (3.2%), due to their tumor nature, degree, clinical manifestations were different, can be expressed Abdominal pain, bloody stools, intestinal obstruction symptoms, etc.

Merkel's diverticulum inspection

1. Small intestine gas angiography:

Because small bowel barium meal is observed at different times, the small intestine position, morphology, peristalsis, and occasionally affected by small intestine filling and expansion, so that the observation is not satisfactory, the distal small intestine interfered with the gastrointestinal fluid, the water of the expectorant The absorption of the lesions affects the display of the lesions, so it is easy to cause missed diagnosis, and the small X-ray examination of the small intestine and enema can better show the shape and lesions of the small intestine. The X-ray features of the double contrast examination of the small intestine cannula of the Michael's diverticulum have :1 The distal part of the ileum protrudes to the outside of the intestine, and has a capsular-like structure perpendicular to the long axis of the intestine, that is, the T sign; 2 the narrow neck sign at the junction of the diverticulum and the ileum, or a triangular mucosal area; Wrinkles, similar to gastric mucosal morphology, Li Ruisheng (1992) reported that this method of examination is the most effective X-ray examination for the diagnosis of this disease.

2.99mTc radionuclide scan:

Jewett (1970) used 99mTc for abdominal radionuclide scanning to diagnose the Meckel's diverticulum. 99mTc has a special affinity for gastric mucosal cells, can be taken up by the gastric mucosa, and is used in the radioactive concentration zone after secretion and secretion. There is a fascinating gastric mucosal tissue and has a secretory function. Therefore, when the 99mTc nuclides are scanned, there may be a radioactive substance-intensive area in the right lower abdomen or the mid-abdomen of the near umbilicus, so that a diagnosis can be made and the lesion location and range can be determined. However, false positive factors and other lesions need to be excluded.

3.B-ultrasound check:

Although it is difficult to detect the presence of diverticulum, it is often possible to make imaging morphological judgments such as inflammation, obstruction of proximal varicose veins or mass in the abdomen, and embedding of foreign bodies in the sputum. For example, intestinal wall edema in the diverticulum area, gross mucosal disorder, Intestinal adhesions into a mass, obstruction of the proximal intestinal tube expansion and reverse peristalsis, as well as strong echo zone of foreign bodies in the sputum, which is conducive to diagnosis and differential diagnosis.

4. Angiography:

For patients with Michael's diverticulum hemorrhage, selective superior mesenteric artery angiography can also be performed, which can show the location and shape of the diverticulum. If there is progressive bleeding, more than 0.5ml per minute, more visible intraventricular wall bleeding spots and patchy shadows. If the amount of bleeding is small, the contrast agent accumulates in the sputum room with a cloud-like shadow. Kusumoto believes that angiography has a high diagnostic value for the discovery of diverticulum and hemorrhage. Another author reported 39 cases of angiography with a diagnosis rate of 59%. Angiography is a method of traumatic examination, but the current vascular puncture technique can be made less traumatic, safe and reliable. Therefore, most scholars believe that this method is a valuable diagnostic method for the disease.

5. Laparoscopy:

The lesions in the diverticulum can be seen directly, and the diverticulum can be removed by laparoscopy under direct vision.

Merkel's diverticulum diagnosis

Diagnostic criteria

Simple mecker's diverticulum without clinical symptoms is difficult to diagnose with common examination methods. Once complications occur, it is difficult to identify with other acute abdomen. Therefore, the diagnosis of this disease mainly depends on the clinician's awareness of the disease and the corresponding selection. The examination means and surgical exploration, low intestinal bleeding, ileal mechanical intestinal obstruction or middle and lower abdominal peritoneal inflammation should consider this disease.

Differential diagnosis

When Meckel's diverticulum causes intestinal obstruction, diverticulitis or perforation, the symptoms and signs appear similar to those of general intestinal obstruction or appendicitis, or basically the same. It is still difficult to make a correct diagnosis before surgery. When gastrointestinal bleeding occurs, Colon polyps, hemorrhagic necrotizing enterocolitis.

1. Colon polyps: generally have a long history of a small amount of blood in the stool, showing a bright red color. If there is polyps falling off, there may be a lot of bleeding, which can cause anemia. The defect of polyps can be seen in the barium enema. The fiberoptic colonoscopy or sigmoidoscopy can be used to diagnose and remove polyps. .

2. Acute hemorrhagic necrotizing enterocolitis: Most of them have diarrhea, which is a salty watery mucus, accompanied by high fever, abdominal pain and toxic shock, often accompanied by intestinal obstruction and signs of peritonitis.

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