Endoscopic retrograde cholangiopancreatography

Endoscopic retrograde cholangiopancreatography is a combination of endoscopy (to locate and cannulate the ampulla of Vater) and radiographic imaging after contrast medium has been injected into the bile duct and pancreatic duct. In addition to imaging the bile duct and pancreas, ERCP allows for imaging of the upper gastrointestinal tract and periampullary area, as well as performing biopsies or performing surgical interventions (e.g., sphincterotomy, gallstone removal, or bile duct stent placement).

To successfully perform endoscopic retrograde cholangiopancreatography and obtain high-quality radiographs, in addition to endoscopes and a set of catheters, an X-ray television unit and radiopaque agents are required. In most cases, ERCP is performed using endoscopes with lateral optics. In patients who have undergone gastric resection using the Bilroth-II method, endoscopes with end or beveled optics must be used to perform endoscopic retrograde cholangiopancreatography.

The requirements for X-ray equipment are quite high. It must provide visual control over the course of the study, obtaining high-quality cholangiopancreatograms at various stages, and an acceptable level of patient irradiation during the study. For endoscopic retrograde cholangiopancreatography, various water-soluble radiopaque agents are used: verografin, urografin, angiografin, triombrast, etc.

Indications for endoscopic retrograde cholangiopancreatography:

1. Chronic diseases of the bile and pancreatic ducts.
2. Suspected presence of stones in the ducts.
3. Chronic pancreatitis.
4. Mechanical jaundice of unknown genesis.
5. Suspected tumor of the pancreatoduodenal zone.

Preparation of patients for endoscopic retrograde cholangiopancreatography.

Sedatives are prescribed the day before. In the morning, the patient comes on an empty stomach. Premedication is administered 30 minutes before the examination: intramuscularly 0.5-1 ml of 0.1% atropine sulfate, metacin or 0.2% platifillin solution, 1 ml of 2% promedol solution, 2-3 ml of 1% diphenhydramine solution. It is unacceptable to use morphine-containing drugs (morphine, omnopon) as narcotic analgesics, as they cause spasm of the sphincter of Oddi. The key to a successful examination is good relaxation of the duodenum. If it is not possible to achieve this and peristalsis persists, then cannulation of the major duodenal papilla (MDP) should not be started. In this case, it is necessary to additionally administer drugs that inhibit the motor function of the intestine (buscopan, benzohexonium).

Methodology for performing endoscopic retrograde cholangiopancreatography.

Endoscopic retrograde cholangiopancreatography includes the following stages:

1. Revision of the duodenum and major duodenal papilla.
2. Cannulation of the major duodenal papilla and trial administration of a radiocontrast agent.
3. Contrast enhancement of one or both ductal systems.
4. Radiography.
5. Monitoring the evacuation of contrast agent.
6. Carrying out measures to prevent complications.

Evaluation of the major duodenal papilla(shape, size, morphological changes, type and number of openings) is of great importance both for diagnosing duodenal diseases (tumor, papillitis, papilla stenosis) and for assessing the anatomical and topographic relationships of the intestine, large duodenal papilla and duct systems. The nature of the discharge from the papilla is of great importance for identifying pathology of the biliary system: pus, blood, putty, sand grains, parasites.

During endoscopic examination of the duodenum, the papilla is found on the inner wall of the descending part of the intestine when viewed from above. Detailed revision of the papilla is difficult with pronounced peristalsis and narrowing of this section caused by cancer of the head of the pancreas, primary cancer of the duodenum, enlarged pancreas in chronic pancreatitis. Of great practical importance is the detection of two papillae of the duodenum - large and small. They can be differentiated by localization, size and nature of the discharge. The large papilla is located distally, the height and diameter of its base vary from 5 to 10 mm, bile is secreted through the opening at the apex. The small papilla is located approximately 2 cm proximally and closer to the front, its size does not exceed 5 mm, the opening is not contoured, and the discharge is not visible. Rarely, both papillae are located next to each other. In such cases, pancreatography is safer and more often successful, since if contrasting through the major papilla fails, it can be performed through the minor papilla.

At the beginning of the examination, the duodenum and the large duodenal papilla are examined with the patient lying on the left side. However, in this position, the papilla is more often visible in the lateral projection and not only cannulation, but also its detailed examination is difficult, especially in patients who have undergone surgery on the bile ducts. A convenient frontal position of the large duodenal papilla for cannulation and radiography can often only be achieved with the patient lying on the stomach. In some cases (in the presence of a diverticulum, in patients after surgery on the extrahepatic bile ducts), the large duodenal papilla can be brought to a position convenient for cannulation only in the position on the right side.

Cannulation of the major duodenal papilla and trial administration of contrast agent.The success of cannulation of the ampulla of the major duodenal papilla and selective contrasting of the corresponding ductal system depends on many factors: good relaxation of the duodenum, the experience of the researcher, the nature of morphological changes in the papilla, etc. An important factor is the position of the major duodenal papilla. Cannulation can only be performed if it is located in the frontal plane and the end of the endoscope is inserted below the papilla so that it is viewed from the bottom up and the opening of the ampulla is clearly visible. In this position, the direction of the common bile duct will be from the bottom up at an angle of 90°, and the pancreatic duct - from the bottom up and forward at an angle of 45°. The actions of the researcher and the effectiveness of selective cannulation are determined by the nature of the fusion of the duct systems and the depth of cannula insertion. The catheter is pre-filled with a contrast agent to avoid diagnostic errors. It should be inserted slowly, accurately determining the opening of the ampulla by its characteristic appearance and the outflow of bile. Hasty cannulation may be unsuccessful due to trauma to the papilla and spasm of its sphincter.

When the openings of the biliary and pancreatic duct systems are located separately on the papilla, to contrast the first of them, the catheter is inserted into the upper corner of the slit-like opening, and to fill the second - into the lower corner, giving the catheter the direction indicated above. With the ampullar variant of BDS, to reach the mouth of the bile duct, it is necessary to insert the catheter from the bottom up by bending the distal end of the endoscope and moving the elevator. It will slide along the inner surface of the "roof of the large duodenal papilla" and slightly raise it, which is clearly noticeable, especially when the bile duct and duodenum merge at an acute angle and there is a long intramural section of the common bile duct. To reach the mouth of the pancreatic duct, the catheter inserted into the opening of the ampulla is advanced forward, having previously introduced a contrast agent. Using the indicated techniques, it is possible to either selectively or simultaneously contrast the bile and pancreatic ducts.

In patients who have undergone surgery (in particular, choledochoduodenostomy), it is often necessary to selectively contrast the ducts not only through the mouth of the large duodenal papilla, but also through the anastomosis opening. Only such a complex study allows us to identify the cause of painful conditions.

X-ray control of the catheter position is possible already with the introduction of 0.5-1 ml of contrast agent. If the cannulation depth is insufficient (less than 5 mm) and the duct system is blocked low (close to the ampulla) by a stone or tumor, cholangiography may be unsuccessful. When the cannula is located in the ampulla of the large duodenal papilla, both duct systems can be contrasted, and with its deep (10-20 mm) introduction - only one.

If only the pancreatic duct is contrasted, an attempt should be made to obtain an image of the bile ducts by introducing the contrast agent when removing the catheter and performing repeated shallow cannulation (3-5 mm) of the ampulla of the major duodenal papilla, directing the catheter upward and to the left. If the cannula is inserted 10-20 mm and the contrast agent is not visible in the ducts, this means that it is resting against the duct wall.

The amount of contrast agent required for cholangiography varies and depends on the size of the bile ducts, the nature of the pathology, previous surgeries, etc. Usually, it is enough to introduce 20-40 ml of contrast agent. It is excreted slowly, and this circumstance allows for X-rays to be taken in the most convenient projections that the doctor chooses visually. The concentration of the first portions of the contrast agent introduced during endoscopic retrograde cholangiopancreatography should not exceed 25-30%. This helps to avoid errors in diagnosing choledocholithiasis as a result of stones being “clogged” with highly concentrated contrast agents.

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