Annular pancreas

Introduction to the annular pancreas During the embryonic stage, the healing position of the two pancreatic buds (pancreas and accessory pancreas) is abnormal. When the duodenum rotates, the ventral pancreatic buds are fixed and prolonged, and the duodenum is lowered after combining with the dorsal pancreatic buds. Surrounded by the pressure, the duodenum causes high intestinal obstruction, called the annular pancreas (annular pancreas), and the pancreatic head of the annular pancreas is still located in the duodenal arch. The tissue of the annular portion contains the same islet and acinar tissue as the normal pancreas. basic knowledge The proportion of illness: 0.002% Susceptible people: no specific population Mode of infection: non-infectious Complications: peptic ulcer cholelithiasis pancreatitis tracheoesophageal fistula

Cyclic pancreatic cause

(1) Causes of the disease

There are many etiology of the annular pancreas. The pancreas is formed by the gradual development and fusion of several protrusions on the original intestinal wall of the embryo. The prominent part is below the stomach, on the plane equal to the liver protrusion, and the dorsal pancreatic protrusion, also known as the pancreas. The anlage occurs directly from the duodenal wall, and the ventral pancreatic protrusion occurs from the root of the liver. Later, the pancreatic projection on the dorsal side develops into the body and tail of the pancreas, and the pedicle becomes the accessory pancreatic duct. The opening is on the inner side wall of the duodenum about 2 cm above the ampulla. The ventral pancreatic protrusion develops slowly, the pedicle is connected to the common bile duct, and later becomes the main pancreatic duct of the pancreas. In normal cases, at about the 6th week of the embryo, as the duodenum rotates, the ventral pancreas should also turn left to the site close to the dorsal process, and then the two As a result, the main pancreatic duct and the accessory pancreatic duct are gradually connected to become a complete pancreas. When there is a developmental disorder, or part of the ventral pancreatic protuberance adheres to the intestine, it will become an ectopic pancreas; or the ventral side Pancreatic protuberance failed to rotate left with the duodenum In turn, it merges with the dorsal pancreatic nodules, and a band of pancreatic tissue surrounds the duodenum, partially or completely surrounding the first or second segment of the duodenum, narrowing the intestinal lumen, ie forming a ring pancreas.

(two) pathogenesis

Most of the annular pancreas are located in the duodenal descending segment, especially in the upper part of the descending segment. Only the individual is located in the duodenal horizontal segment or the duodenal ampulla. The annular pancreas is generally about 1 cm wide, and most of the segments are only partially Wraps around the duodenum, accounting for 2/3 to 4/5 of the circumference of the intestine, that is, a 1 to 1.5 cm interval, which is often located in the anterior or lateral wall of the duodenum, annular pancreas and normal pancreatic tissue. It has the same structure and contains islet tissue, acinar and ductal system. Therefore, strictly speaking, it is only a kind of deformity. It can not be considered as a pathological phenomenon in histology, but the duodenum of the pancreatic ring can be thin and lose normal. Mucosal structure, the lumen of the annular pancreatic tissue may not communicate with the main pancreatic duct, but open to the duodenum alone, which may be the main factor contributing to pancreatitis.

Annular pancreatic prophylaxis

For patients with biliary obstruction, in addition to the removal of obstruction of the duodenum, it is necessary to remove the obstruction of the biliary tract, and it is feasible to remove most of the stomach. Billoth-II anastomosis plus the distal end of the common bile duct and duodenal obstruction Anastomosis, for patients with annular pancreas with stomach, duodenal obstruction, feasible subtotal resection, Billoth-II anastomosis, if necessary, additional vagus nerve surgery.

Annular pancreatic complications Complications peptic ulcer cholelithiasis pancreatitis tracheoesophageal fistula

It has been considered that peptic ulcer, cholelithiasis, and pancreatitis are the three major complications of the annular pancreas. The statistical incidence of Yogi et al is 24.8%, 16.2%, and 10.5%, respectively, and the incidence of malignant tumors in patients with annular pancreas is reported as high. 8.6%.

Peptic ulcer

The ring-shaped pancreas is often complicated by gastric and duodenal ulcers. Duodenal ulcer is common, mostly occurs after the ball. Sometimes the ulcer is located in the duodenum surrounded by the annular pancreas. The cause of the ulcer and the stomach The acidity of the duodenal contents is too high and the retention of the contents is related to gastrointestinal mucosal damage.

2. Cholelithiasis and obstructive jaundice

Because the annular pancreas is located in the ampulla of the ampulla, or the duodenal descending segment is obviously narrowed due to the annular pancreas, the upper segment is obviously dilated, and the common bile duct is compressed. It can also cause bile duct obstruction due to pancreatitis. Poor drainage of the fluid is easy to form gallstones, bile duct stones can cause jaundice, and the common bile duct pressure or pancreatitis can cause obstructive jaundice.

3. Pancreatitis

Pancreatitis is often the main cause of the symptoms of the ring pancreas and becomes the cause of the patient's visit. The edema of acute pancreatitis or the scar fibrosis of chronic pancreatitis and adhesion to nearby organs can aggravate duodenal obstruction. Pancreatitis can be used. It is limited to the annular pancreatic part or invades the whole pancreas. The cause of pancreatitis may be related to the abnormal opening of the pancreatic pancreatic duct, or the lower end of the common bile duct, which causes the bile fluid to flow back into the pancreatic duct and stimulate trypsin activation.

4. Some patients with other congenital diseases may be associated with other congenital dysplasia, including Down's syndrome, duodenal atresia, small bowel malrotation, congenital heart disease, tracheoesophageal fistula, esophageal atresia, Meckel's diverticulum, Anal atresia, no gallbladder, etc.

Annular pancreatic symptoms common symptoms dehydration abdominal pain jaundice

Clinically, the annular pancreas is often divided into neonatal and adult types, and its clinical manifestations are closely related to the degree of compression of the duodenum and other pathological changes.

(1) Neonatal type

More than 1 week after birth, more than 2 weeks of onset, rare manifestations of acute complete 12-guided intestinal obstruction, sick children with refractory vomiting, vomit contains bile, due to frequent vomiting, can continue dehydration, Electrolyte disorder and acid-base balance disorders, malnutrition, such as incomplete 12-finger obstruction, it is intermittent abdominal pain and vomiting, may be accompanied by upper abdominal fullness discomfort, increased after eating, the above symptoms can be repeated, in addition The ring-shaped pancreas is often accompanied by other congenital diseases such as tongue-like dementia, esophageal atresia, esophageal tracheal fistula, Meckel's diverticulum, congenital heart disease, and deformed foot.

(2) Adult type

More common in 20 to 40 years old, more manifested as symptoms of duodenal chronic incomplete obstruction, and the sooner the symptoms appear, the more severe the performance of duodenal obstruction, the patient mainly has repeated upper abdominal pain and vomiting, showing A seizure, increased abdominal pain after eating, can be relieved after vomiting, vomit is gastric duodenal juice, containing bile, in addition to duodenal obstruction, patients can also be complicated by other pathological changes, and cause the corresponding clinical symptoms.

Peptic ulcer

Patients with annular pancreas complicated by stomach and duodenal ulcer can reach 30-40%, of which duodenal ulcer is more common. The cause of ulcer may be related to the compression of annular pancreas, long-term retention of gastric juice and stomach. It refers to the high acidity of the contents of the intestines.

2. Acute pancreatitis

Patients with annular pancreas complicated with pancreatitis account for 15-30%. The cause may be related to pancreatic ductal system abnormalities. Pancreatic juice stasis or bile reflux to the pancreatic duct may cause disease. Pancreatitis may be limited to the annular pancreas or invade the whole pancreas. Edema of acute pancreatitis or fibrous scarring of chronic pancreatitis may also aggravate duodenal obstruction.

3. Biliary obstruction

It is rare in clinical practice. Because the annular pancreas is located in the ampulla of the spleen, the annular pancreas causes the second segment of the duodenum to be obviously narrow and compresses the common bile duct and pancreatitis, etc., which can cause obstruction of the lower common bile duct. Astragalus, a long-term disease can also be secondary to biliary stones.

Annular pancreas

Laboratory tests did not directly help, serum bilirubin could be elevated, and vomit contained bile. Neonatal duodenal pancreas caused complete obstruction of the duodenum, and squamous epithelial cells and lanugo could not be found in meconium.

Abdominal plain film

Mainly manifested as duodenal obstruction, the laparoscopic film showed dilatation of the stomach and duodenal ampulla, and the so-called double bubble sign appeared, because the stomach and duodenum ampulla often have a large number of fasting stays. Liquid, so there is a liquid level in the ampulla of the stomach and the duodenum in the standing position. Sometimes the upper and lower intestines of the duodenal stenosis area are flattened, so that the narrow area is set off.

2. Gastrointestinal tincography

It is characterized by dilatation of the stomach, sagging, a large amount of fasting stagnant fluid, and prolonged emptying time. The duodenum ampulla is enlarged and elongated, and the lower edge is smooth and round, the duodenum descends, and occasionally the first segment or In the third segment, there was a marginal stenosis with narrow margins. The stenosis of the stenosis was rare, and it became eccentric and centripetal. The intestines above the stenosis showed reverse motility (Fig. 1), and the presence of ulcers was observed. .

3.ERCP

Microscopic angiography can visualize the annular pancreatic duct and is very helpful for diagnosis (Fig. 2). The duodenal stenosis caused by the annular pancreas is often near the main nipple. If the endoscope cannot pass the stenosis, the angiography cannot be performed. Sometimes the common bile duct stenosis appears at the end of the common bile duct due to the annular pancreas.

4.CT

After oral administration of the contrast agent, the duodenum is filled, and the pancreatic tissue surrounding the duodenum is continuously continuous with the pancreatic head. Usually, the annular pancreatic tissue is thin, and the annular pancreas is difficult to directly develop. If the pancreatic head is seen, Indirect signs such as enlarged and duodenal descending hypertrophy and stenosis are also helpful for diagnosis.

5. Magnetic resonance (MRI) and magnetic resonance cholangiopancreatography (MRCP)

MRI can see the tissue structure that is consistent with the pancreatic head and the same signal intensity around the duodenum and the pancreas. It can be confirmed as pancreatic tissue. MRCP can display the circular pancreatic duct through the principle of water imaging. 3), MRCP is non-invasive, no radiation, the patient is painless, simple and convenient.

6. Endoscope

Usually the endoscopic mucosa is normal, and it does not help the diagnosis. In more severe cases, the duodenal descending part of the duodenal can be seen as a ring-shaped stenosis, which can be combined with duodenal ulcer.

Diagnosis of annular pancreas

diagnosis

The diagnosis of the annular pancreas is not easy. According to typical symptoms and signs, combined with X-ray findings, the possibility of the disease should be considered, but some cases are clearly diagnosed during surgery.

Differential diagnosis

When considering a ring-shaped pancreas, it should be differentiated from the following diseases.

1. Congenital duodenal atresia can be seen in neonates. The lesions are located in the descending duodenum. Frequent vomiting after birth. The vomit can contain bile. The sputum can not pass through during gastrointestinal angiography. No gas, no pancreatic tissue environment can be seen in the descending duodenum during surgery.

2. Congenital pyloric hypertrophy often causes nausea and vomiting several weeks after birth. The vomit contains no bile. The upper abdomen is more bulging, and there may be gastric peristalsis. 95 to 100% of the sick children can lick the olive in the right upper abdomen. Tumor mass, gastrointestinal sputum angiography see gastric dilatation, pyloric tube thinning, lengthening, gastric emptying time and so on.

3. Superior mesenteric artery compression syndrome This disease refers to the chronic obstruction caused by the compression of the superior or superior mesenteric artery in the third or fourth segment of the duodenum. It is mainly characterized by upper abdominal fullness discomfort, intermittent vomiting, and vomit. Containing bile, gastrointestinal sputum angiography showed significant blockage and dilation in the duodenum, and the expectorant was blocked in the third or fourth segment of the duodenum.

4. Patients with pancreatic head or uterine abdomen tumors with annular pancreas with jaundice, especially the elderly, should be differentiated from pancreatic head or duodenal papillary tumor, and the latter can be seen in the gastrointestinal angiography. The inner edge of the lower part is compressed and deformed, the mucosal folds are destroyed, and there are filling defects, and the "3" sign, bilateral sign, etc.

5. Congenital choledochal atresia in the case of obvious jaundice, should be identified with the disease, jaundice after birth and gradually deepened, vomit does not contain bile, barium meal examination duodenal descending segment without stenosis and obstruction.

In addition, it should be differentiated from diseases such as duodenal tuberculosis and low duodenal ulcer.

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