Annular Pancreas - Types, Causes, Symptoms, Diagnosis, and Treatment

What Is Pancreas and What Are Its Functions?

The pancreas is an organ that is a part of the digestive as well as the endocrine system of the human body. The pancreas is present in the abdomen behind the stomach. It functions both as an endocrine and an exocrine gland. However, 99 % of the pancreas works as an exocrine gland, and only one percent functions as an endocrine gland. The exocrine functions of the pancreas include; the secretion of pancreatic juice into the duodenum (first part of the small intestine) and the secretion of digestive enzymes. As an endocrine gland, the pancreas plays a vital role in the regulation of blood sugar levels and secretion of the hormones like insulin, glucagon, somatostatin, and pancreatic polypeptide.

What Are Annular Pancreas?

The annular pancreas is a rare condition affecting the pancreas in which the second part of the duodenum is surrounded by a ring of pancreatic tissues, which is continuous with the head of the pancreas. This can lead to constriction in the duodenum and block the flow of food in the rest of the intestines. The ring of pancreatic tissues does not interfere with the functioning of the pancreas, but it does cause some symptoms. In contradiction, not all cases are symptomatic. The annular pancreas is the most common birth defect affecting the pancreas. It is estimated to be affecting one out of every twelve thousand or fifteen thousand newborns.

What Are the Types of Annular Pancreas?

The annular pancreas is of the following types:

1. Complete Annular Pancreas: Pancreatic tissues or the annular duct surround the second part of the duodenum.

2. Incomplete Annular Pancreas: The annular duct does not surround the second part of the duodenum; this will give a “crocodile jaw” appearance.

What Causes Annular Pancreas?

The annular pancreas is a congenital defect, and the exact cause of this condition is still unknown. However, the annular pancreas is associated with abnormal embryological development. It occurs with several other congenital and other defects like:

• Down syndrome (a clinical condition in which an individual has an extra chromosome).

• Tracheoesophageal fistula (an abnormal connection between trachea and esophagus).

• Intestinal atresia (failure of a portion of the intestine to form completely).

• Pancreas divisum (a birth defect in which ducts of the pancreas do not join).

• Pancreatitis.

• Pancreatic cancer.

• Intraductal papillary mucinous neoplasm (IPMN) is a type of tumor that occurs within the cells of the pancreatic duct.

What Are the Symptoms of Annular Pancreas?

In some cases, doctors can diagnose the defect in babies even before birth, and in some cases, the disease may not be diagnosed until the symptoms start showing. The symptoms of the annular pancreas are:

• Polyhydramnios or excess amniotic fluid.

• Low weight at birth.

• Feeding intolerance immediately after birth.

• Epigastric distention (abnormally swollen abdomen).

• Swollen belly.

• Feeling full after eating a small portion.

• Nausea and vomiting.

How Is Annular Pancreas Diagnosed?

A diagnosis of the annular pancreas is made after taking a detailed medical history of the patient along with multiple imaging tests and other tests. While taking the medical history, the doctor will precisely evaluate the presence of any other congenital disease in the patient. After taking a detailed medical history and studying the physical symptoms, the following test is done to confirm the diagnosis of the annular pancreas:

1. X-ray of the Abdomen: The X-ray of the abdomen of an individual affected by the annular pancreas will show an “e” sign which is an indication of duodenal obstruction and presence of air in the stomach and duodenum. However, the “double bubble” sign is not characteristic of the annular pancreas as it is also seen in other conditions like duodenal atresia (improper development of the first part of the small intestine) and intestinal malrotation (intestines do not form into a coil during development). A double bubble sign is an indication of dilatation of the stomach in the upper left quadrant and proximal duodenum in the right upper quadrant.

2. CT Scan: The CT (computed tomography) scan of a person affected by the annular pancreas will show pancreatic tissues completely or incompletely surrounding the second part of the duodenum. Associated duodenal narrowing and dilatation of the surrounding duodenum are also observed.

3. MRI: In the MRI (magnetic resonance imaging) of a person having an annular pancreas, the pancreatic ductal anatomy can be observed as well. The annular duct is seen joining the pancreatic duct or the accessory duct (known as the duct of Santorini).

4. Upper Gastrointestinal Series: It is the radiographic evaluation of the upper gastrointestinal tract. The esophagus, stomach, and the first part of the duodenum are assessed in this test. In the case of the annular pancreas, the upper gastrointestinal series shows narrowing of the second portion of the duodenum and dilatation of the proximal part of the duodenum.

5. Small Bowel Series: Small bowel series is a test that uses fluoroscopy (real-time X-ray) and barium-based contrast material to produce an image of the small intestine.

How Is Annular Pancreas Treated?

The cornerstone for treatment of the annular pancreas is surgery to bypass the pancreatic tissues, which will relieve the obstruction in the duodenum. The goal of the treatment is to remove the obstruction so that the small intestine can function efficiently. The surgical procedures for the annular pancreas include:

1. Gastrojejunostomy.

2. Duodenojejunostomy.

In these procedures, the surgeon will cut the part of the intestine at the site of blockage and then reconnect it with the area below the obstruction.

What Are the Complications of Annular Pancreas?

If left untreated for long, the annular pancreas can cause several complications, including:

• Complete blockage of the duodenum.

• Liver inefficiency.

• Small intestinal ulcers.

• Jaundice.

• Pancreatic cancer.

What Is the Prognosis of Annular Pancreas?

After proper treatment of the annular pancreas, which is surgery, the long-term outlook or the prognosis of the condition is excellent. However, precautions are needed to be taken because adults with an annular pancreas can develop complications like jaundice, duodenum blockage, ulcers in the small intestine, poor functioning of the liver, etc. Patients affected by the annular pancreas are also prone to certain types of cancers.

Conclusion:

The annular pancreas is a rare disorder affecting the pancreas and the duodenum. It is characterized by the presence of a ring of pancreatic tissues surrounding the second part of the duodenum that is continuous with the head of the pancreas. The annular pancreas can be complete or incomplete, and the condition may be associated with other congenital disorders. The annular pancreas has multiple causes and symptoms. The diagnosis of the condition is mainly based on medical history and imaging tests. The treatment of choice for the annular pancreas is surgery.