What Is an Annular Pancreas?

The circular pancreas is a type of pancreas that surrounds the duodenum and forms a circular pancreas. It is a congenital malformation.

Basic Information

Visiting department: Gastroenterology
Common causes: During the development of the pancreas, the ventral primordium failed to fully rotate to the left with the midgut, and the pancreas formed thereby could surround the duodenum and become a circular pancreas.

Common symptoms: Obstruction, mild asymptomatic throughout life, severe in duodenal obstruction occurs in infancy.
Contagious: no

Causes of Circular Pancreas

At the 4th week of the normal pancreas, the ventral primordium rotates clockwise with the proximal midgut, and at the 7th week of the embryo, it completely fuses with the dorsal primordia to form a complete pancreas. If during the development of the pancreas, the ventral primordium fails to fully rotate to the left with the midgut, the pancreas formed thereby can surround the duodenum and become a circular pancreas.

Clinical manifestations of circular pancreas

The pancreatic tissue surrounds the descending part of the duodenum and is connected to the head of the pancreas. Due to the different degree of obstruction caused by malformations, mild cases can be asymptomatic throughout life, or symptoms can be extended into adulthood; severe cases can have duodenal obstruction in infancy and even neonatal period.

Circular pancreatic examination

1. The abdomen X-ray film mainly shows duodenal obstruction. The stomach and duodenal ampulla show dilation and flatulence in the supine position, and the so-called double-bubble sign appears; the erect radiograph shows the stomach and duodenal ampulla. Each abdomen has a fluid level, and sometimes the intestinal canal is inflated above and below the duodenal stenosis area, thereby setting up the stenosis area.
2. Gastrointestinal barium angiography manifests gastric dilation, sagging, a large amount of fasting retention fluid, prolonged emptying time, duodenal ampulla symmetrically enlarged, elongated, duodenal descending segment, occasionally the first segment or The third segment appeared with a narrow marginal narrow stenosis. The mucosal folds in the stenosis were rare and turned into eccentric and concentric longitudinal lines. Intestinal peristalsis above the stenosis was seen, and ulcers were found.
3.ERCP
Endoscopic angiography can make the circular pancreatic duct develop, which is extremely helpful for diagnosis. Duodenal stenosis caused by the circular pancreas is often near the main nipple. If the endoscope fails to pass through the stenosis, it can not be contrasted. A common bile duct stenosis appears on the distal end of the common bile duct.
4.CT
After oral administration of the contrast agent, the duodenum is filled, and the pancreatic tissue surrounding the descending duodenum is continuously seen with the pancreatic head. Usually, the circular pancreatic tissue is thin, and the circular pancreas is difficult to be directly developed. Indirect signs such as enlarged head and hypertrophy and stenosis in the descending duodenum are also helpful for diagnosis.
5. Magnetic resonance and magnetic resonance pancreaticobiliary angiography (MRI) can see the tissue structure around the descending duodenum and the pancreas with the same signal intensity as the pancreas head, which can be confirmed as pancreatic tissue. Contrast imaging (MRCP) can well show circular pancreatic duct shadows. MRCP is non-invasive, non-radiation, pain-free, simple and convenient.
6. Endoscopy usually has normal mucosa under endoscopy, which is of little help for diagnosis; in more severe cases, ring-shaped narrowing of the descending duodenum can be seen under endoscopy, which can be accompanied by duodenal ulcers.

Circular pancreas diagnosis

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

Differential diagnosis of circular pancreas

The circular pancreas should be distinguished from the following diseases.
1. Congenital duodenal atresia is occasionally seen in newborns. The lesion is located in the descending duodenum. Frequent vomiting after birth. The vomit may contain bile. Barium cannot pass at all during gastrointestinal imaging. Gas, no pancreatic tissue surrounds the descending duodenum during surgery.
2. Congenital pyloric hypertrophy occurs nausea and vomiting a few weeks after birth. Vomiting does not contain bile, the upper abdomen is swollen, and there may be gastric motility waves. 95% to 100% of children can be affected in the right upper abdomen. Olive mass, gastrointestinal barium radiography showed gastric dilatation, pyloric ducts became thinner and longer, and gastric emptying time prolonged.
3. The superior mesenteric artery compression syndrome refers to the chronic obstruction caused by the compression of the superior mesenteric artery in the third or fourth segment of the duodenum. It is mainly manifested as upper abdominal fullness and discomfort, intermittent vomiting, and bile in the vomit. Gastrointestinal barium angiography showed significant duodenal blockade and dilatation, and barium was obstructed in the third or fourth segment of the duodenum.
4. Pancreatic head or ampullary tumor of the pancreas. Patients with circular pancreas with jaundice, especially the elderly, should be distinguished from pancreatic head or duodenal papillary tumors. The latter shows that the duodenal ring is enlarged and decreased. The inner edge of the department was deformed by compression, the mucosal folds were damaged, and there were filling defects, inverted "3" sign, bilateral sign, etc.
5. Congenital atresia of common bile duct should be distinguished from the circular pancreas in cases with obvious jaundice. Jaundice appears and deepens after birth. The vomit does not contain bile fluid. Barium meal has no stenosis and obstruction in the descending duodenum .
In addition, it should be distinguished from diseases such as duodenal tuberculosis and low duodenal ulcer.

Circular pancreas treatment

If there are no clinical symptoms, no treatment is needed. Due to the narrowing of the descending duodenum of the pancreatic pancreas, the principle of treatment must be to remove the obstruction of the descending duodenum and the corresponding complications to restore the duodenal patency.
There are many surgical methods to remove the obstruction of the descending duodenum, which can be roughly divided into two categories, one is surgery to release the obstruction; the other is food bypass (shortcut) surgery.

Prognosis of circular pancreas

As long as the diagnosis is timely and there are no serious accompanying abnormalities, the overall prognosis of duodenal obstruction caused by circular pancreas in neonates is good, and long-term follow-up is necessary. The prognosis of adult patients is related to the degree of duodenal stenosis, the accompanying pathological manifestations and the general situation of the individual.