Annular Pancreas

The most frequent abnormality of the pancreas is annular pancreas in which a thin flat band of pancreatic tissue surrounds the first part of the small intestine (duodenum) and continues on either side into the head of the pancreas. (Figure 1)

This “ring-shaped” or “annular” tissue has an abnormal shape but works like a normal pancreas. In most cases of annular pancreas, there is also narrowing or blockage of the first part of the small intestine at that spot. Down’s syndrome occurs in approximately one fourth of patients. Other problems such as an abnormal position of the intestines (malrotation), an abnormal connection between the windpipe and the tube that carries food from the mouth to the stomach (tracheoesophageal fistula), and heart defects occasionally occur in patients with annular pancreas. Symptoms from annular pancreas usually appear in babies but occasionally not until older children, depending on the degree of blockage.

Annular pancreas is a cause of severe blockage of the first part of the small intestine in the fetus and may produce increased amniotic fluid in the mother. Ultrasound may identify the problem before birth. The double-bubble sign of air in the stomach and the first part of the small intestine on belly x-ray looks like that seen with simple blockage of the duodenum. Otherwise x-rays may show narrowing of the duodenum with small amounts of air further down the intestine.

The operation is done through an incision made in the right upper part of the belly. When annular pancreas is found, an intestinal bypass should be done around the annular blockage without disturbing the annular pancreas itself because of the risk of injuring the pancreatic tube within it, which could result in a chronic leak of pancreas enzymes and fluid. With this surgery, long-term results are excellent, and pancreatitis after surgery is exceedingly rare.

Article and graphics adapted from O'Neill: Principles of Pediatric Surgery. © 2003, Elsevier.

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