Endoscopic retrograde cholangiopancreatography

During this procedure an X-ray is taken of the pancreatic duct and bile ducts. These ducts drain secretions from the pancreas and liver respectively. Obtaining such pictures requires that an endoscope be placed in the mouth through the esophagus and stomach, then into the duodenum.

The patient is sedated and given potent pain relievers (opiate) after on overnight fast. A local anesthetic is sprayed to the back of the throat. Frequently, muscle relaxants are used to relax the duodenum and ampulla (an anticholinergic drug, or glucagon, nitroglycerin). During the test patients are monitored to ensure that they are not oversedated. The monitoring includes a pulse oximeter (a probe fastened to the patient's finger that measures blood oxygen concentration) and a heart rate monitor. During the ERCP, the degree of sedation is much greater than that used for an EGD, so often the patient is asleep.

Using a modified endoscope, the investigator visualizes the duodenum on a monitor and finds the small opening where the bile duct and pancreatic duct empty into the duodenum (the ampulla of Vater). A thin catheter is passed through an opening in the endoscope and through the ampulla. Once the catheter has been placed through the opening (cannulated), a dye is injected into the pancreatic and bile ducts. This enables images of these ducts to be obtained. X-rays are taken of the abdomen over the area of the pancreas and are examined by the attending physicians on screen.

Despite the medication, occasionally the patient may feel discomfort and may retch. If discomfort occurs additional pain relief is usually provided. Symptoms arising from complications may also rarely occur.

• Will show the indirect effects of pancreatic cancer such as blockage or dilatation of the ducts and inflammation of the tissue. Similar symptoms can be caused by conditions such as chronic pancreatitis or stones in the pancreatic or bile ducts. By examining the pattern of these changes, it is possible to predict with a high degree of certainty if an abnormality is a cancer.

• An ERCP can detect an abnormality suspicious of cancer in about 9 out of 10 patients who are investigated for possible adenocarcinoma. Patients who have very small cancers, less than 2 cm, that currently do not alter the main ducts of the pancreas or the bile duct will not be visible.

• Occasionally, it can be very difficult to tell if an abnormality in the pancreatic duct is due to cancer or inflammation. Tissue biopsy provides confirmation of the presence of cancer (link to FNA and cytology). This test is not useful in detecting most endocrine types of pancreatic cancer.

If the test results are abnormal, a sample of pancreatic fluid from the pancreatic duct or a sample of tissue by biopsy can be obtained if necessary. This can be done either during the ERCP by positioning a biopsy forceps while looking at it on screen. Alternatively, the fluid or tissue sample can be obtained by visualizing the are of concern using other imaging techniques and performing a needle biopsy (FNA).

As a treatment:

Most importantly, if a pancreatic cancer is present and the patient is not a candidate for curative surgery, therapeutic procedures can be performed using ERCP. These procedures can provide considerable relief for the patient with minimal inconvenience or risk. Pancreatic cancers frequently block the bile duct that prevents the proper flow of bile from the liver. The therapeutic intervention typically alleviates symptoms caused by duct blockage such as jaundice, generalized and progressive itching, liver damage, inadequate digestion of food, a risk of bacterial infection of the blood and severe pain. Placing a stent into the bile duct to allow bile drainage can extend an individual's life and improve their quality of life. The patient does not feel the presence of the stent in their bile duct or pancreatic duct.

The main complications of the ERCP as a diagnostic procedure are pancreatitis, infection and bleeding.

The insertion of a therapeutic stent can have complications such as bleeding, inflammation of the pancreas (pancreatitis), bile duct damage and leakage, and infection. Bleeding and pancreatitis is more likely if a large (wide-bore) stent is placed as it requires a cut to be made to enlarge the opening of the narrow ampulla where the bile and pancreatic fluid enters the duodenum (see figure). The cut primarily targets a small sphincter muscle surrounding the ampulla (hence, the procedure is termed a sphincterotomy).

Overall, less than 1 in 10 individuals will have such a complication and severe life-threatening complications are rarer (1-2%). The risk of a complication when a sphincterotomy is not performed is less (2-5%) and depends on the number and size of the stents inserted. Usually therapeutic ERCP can be done as a same day procedure without the need for an overnight hospital stay. If complications occur or are suspected hospitalization might be required. Biliary stents usually succumb to blockage after several months as a result of further cancer growth. This may require periodic stent replacement.

There is also a small risk of an allergic reaction to the dye, which contains iodine. Rarely, drugs used to relax the ampulla of Vater can have side effects such as nausea, dry mouth, flushing, urinary retention, rapid heart rate (sinus or supraventricular tachycardia), or a drop in blood pressure.