Process Of Endoscopic Retrograde Cholangiopancreatography Biology Essay

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Endoscopy is the insertion of a thin flexible fiber optic camera with a large light source into the human body. In this situation, the endoscope is advanced down the esophagus, through the stomach, out the duodenum, and through the duodenal loop to the papilla of Vater. A Gastroenterologist, who is trained in diagnosing and treating various illness of the gastrointestinal tract, introduces the endoscope. Retrograde refers to the injection of contrast in the opposite direction of that the body works normally. We, as Radiologic Technologists, are used to that term and concept due to our experience in barium enemas. "Cholangio" refers to the bile duct system and "pancreat" refers to the pancreas. Graphy, of course stands for x-ray radiographs. Thus, the ERCP is an endoscopic procedure that utilizes retrograde filling of the bile duct systems with contrast under fluoroscopy guidance. The ERCP has eliminated the need for some surgeries and T-tube cholangiograms.

Stones are produced when cholesterol or bilirubin settle out of the bile, crystallize, and group together. In the U.S. almost 80% of patients with gallstones have cholesterol gallstones. When one of these stones grow larger or a collection of small sludge like particles collect in the common bile duct, the bile is unable to leave the system. Strictures or post-operative problems may cause the same effects as stones. All of which can cause bile to back up into the liver and the patient may develop jaundice, have abdominal pain, and decreased liver function. The most common risk factors for forming gallstones include being female, over forty, obese, eat a Western diet, and a genetic predisposition. Untreated obstruction of the bile ducts can result in an infection in the liver, bile ducts, or the pancreas. This bacterial infection can quickly create other infections throughout the body.

THE ENDOSCOPE

Philippe Bozzine demonstrated the first endoscope in 1806 at Vienna. It consisted of a simple silver tube, which at one end was lightened by a candle, and a mirror reflected the light. In 1877, Max Nitze fabricated the endoscope, which looks very much like a modern rigid endoscope commonly used in the operating room today. It had distal illumination, a lens system, and an instrument channel. After the invention of the light bulb, the illumination greatly improved. Out with the candle, and in with the electric bulb. In 1930, the first flexible endoscope was invented. In 1951; Professor Harold Hopkins invented the clad fiber. The clad fiber allowed light to travel from one end of the scope to the other in a bundle of fibrous wires. In 1958, the first clinically used flexible fiber optic gastroscope was used. Ludwig Demling and Meinhard Classen performed the first ERCP in 1973. The fiber optics in today's scopes not only emits light, but also transmits images back to a monitor. Endoscopes are designed to either view anatomy directly in front of the scope or they can be angled to view the sides of the anatomy. For ERCP's the side viewing scope is needed in order to visualize the papilla of vater.

The light source is coming up from the bottom of the picture. The dials on the top left side are used to move the endoscope right or left, flex, or extend the tip, to add air or equipment, or to remove objects like foreign bodies, stones, or equipment.

The fiber optics in the endoscope is very complex. The scope uses two fiber optic lines. One line carries light into the body from the scope, and the other line carries the image of the body back to the doctor where it is either displayed on a monitor or visualized through the end of the scope. The endoscope also has a separate port that is used as a working channel to introduce equipment and objects, such as guide wires, brushes, snares, stone baskets, and stents. The importance of the light source cannot be down played. Think about what you can see inside a cave with a flashlight, you would receive limited information. You would miss a small crevasse in the rocks; you might miss a bat on the ceiling, or even a bear sleeping at the other end of the cave. Now image what you could see with a halogen light bulb attached to a helmet. The details of the cave would be seen much more easily. It is likely that you would see several of the small crevasses in the rocks, and even the bat on the ceiling, but you might not see the bear yet. Imagine 10 halogen light bulbs attached to a tall pole and have all the lights angled in different directions, now you would see all of the small crevasses, the bat, and the bear. The light source for the endoscope has to be the best quality.

WHY AN ERCP IS ORDERED

There are numerous reasons that the GI doctor may order an ERCP. The most common symptoms that a patient presents with are abdominal pain and jaundice. The jaundice may be slight, thus liver enzyme lab work may be ordered, but commonly the patient's eyes and skin may be yellow. The pain usually is limited to the right upper quadrant, with the pain varying from mild to intense. The pain fluctuates over a period of time. Other symptoms include nausea, vomiting, and if an infection is involved the patient may also have a fever. Suspected bile duct stones, gallbladder stone, acute pancreatitis, chronic pancreatitis, cholangitis, periampullary tumor, pancreatic/biliary tumor, biliary/pancreatic cyst, stent occlusion, or complications following biliary surgery are all reasons that an ERCP may be ordered. A RUQ ultrasound, CT of the abdomen, or Magnetic Resonance Cholangio Pancreatiogram (MRCP) may have been done previously, which indicated the need for an ERCP. It is always helpful to have all previous studies available for the GI doctor to review prior to the exam.

THE PROCEDURE

Prior to the ERCP, the patient has routinely had lab tests done. Liver function tests are performed on blood samples prior to an ERCP being ordered. This may include any of the following tests:

Test

What is measured

What may be indicated

Alkaline Phosphatese

An enzyme produced in the liver, bone, and placenta that is released during an injury

Bile duct obstruction, liver injury, and some cancers

Alanine Transaminase (ALT)

An enzyme produced in the liver that is released into the blood when liver cells are injured

Liver cell injury (Possible hepatitis)

Aspartate Transaminase (AST)

An enzyme released into the blood when the liver, heart, muscle, or brain is injured

Injury to the liver, heart, muscles, or brain

Bilirubin

A component of the bile produced by the liver

Obstruction to bile outflow, liver damage, excessive breakdown of red blood cells

Gamma-Glutamyl transpeptidase

An enzyme produced by the liver, pancreas, and kidneys and released when there is an injury to those organs

Organ damage, drug toxicity, alcohol abuse, disease of the pancreas

Lactic Dehydrogenase

An enzyme released when certain organs are injured

Damage to the liver, heart, lung, or brain and excessive breakdown of red blood cells

5'-nucleotidase

An enzyme contained only in the liver and released when the liver is injured

Bile duct obstruction or impaired bile flow

Albumin

A protein produced and released by the liver, whose function is to hold fluid inside the blood vessels

Liver damage

Alpha-fetoprotein

A protein produced by the fetal liver and testes

Severe hepatitis or cancer of the liver or testes

Mitochondrial antibodies

Circulating antibodies against mitochondria, an inner component of cells

Liver damage or poor absorption of vitamin K caused by a lack of bile

Prothrombin Time

Time needed for blood to clot (clotting requires vitamin K and substances made by the liver)

Liver damage or poor absorption of vitamin K caused by a lack of bile

Chart from Merck Manual of Medical Information Home Edition, Chapter 115 "Diagnostic Tests for Liver and Gallbladder Disorders," page 558

A contrast assessment should also be done prior to the procedure. If the patient is allergic to iodine contrast, the patient must be pre-treated with medications prior to the exam. The patient could be given either 40 mg prednisone 12 hours and 2 hours before the exam or 40 mg for 3 days before the exam. This combination of medications has proven to be effective in preventing contrast reactions in most patients. Gadolinium that is used for MRI contrasted studies is a good alternate. Gadolinium is less dense, but it will work with a higher KvP than normal, but only if the patient is less than 175 pounds. Patients with larger body masses than that, does not allow the contrast and detail under fluoroscopy to produce enough information for a diagnostic procedure. Non-ionic tri-iodinated x-ray contrast is the contrast of choice.

The patient gives consent to the GI doctor who explains the procedure and the possible risks and complications. The ERCP does have a 10% chance of complication, but the risk drops to 2-5% when a sphincterotomy is not performed. Severe complications occur only 1-2% of the time. Pancreatitis is the most common complication, which is caused by irritation to the pancreatic ducts. The irritation occurs because of injecting the pancreatic duct either too often or administering too much contrast. If this is suspected the GI doctor will usually place a temporary stent in the pancreatic duct.

Bleeding is another complication, which may occur after a sphincterotomy, the removal of stones, or the placement of a stent. The bleeding usually stops without medical intervention, but an injection of Epinephrine at the hemorrhaging site could be used. This can be done through the catheter within the endoscope. A transfusion may be necessary in rare instances. Infection is a small concern that is also discussed with the patient prior to the test. The most severe risk during an ERCP is the perforation of the bowel wall or bile duct. This occurs very rarely, but the patient should be advised of the potential risk. The benefit of the procedure greatly outweighs the risks and the other option, which is usually surgery.

An ERCP procedure team routinely consists of two nurses, a Radiologic Technologist, and the GI doctor. After the patient has signed the consent, the GI nurses apply heart rate monitor leads, O2 nasal cannula, blood pressure cuff, pulse monitor, and a grounding pad. An IV will be started if one is not already present. The heart monitor leads are placed on the patients back and it is best to make sure that they are to the patients left side, out of the right upper quadrant. The patient is then placed on the fluoroscopy table in the left anterior oblique (LAO) position, with their head looking to the right and their right hand with the IV, will be placed up by the pillow. This allows the nurse easier access to administer medication through the IV port, and it also helps position the patient for the exam. A small lead apron should be placed underneath the patient when indicated. Routinely, if the lead is placed no higher than the crest of the pelvis it is adequately protecting the patient without obscuring any anatomy. This is also an appropriate time to double check the leads on the patients left side of their back and to make sure the patient is warm and comfortable.

A nurse will assist the doctor during the procedure by manipulating wires and catheters, and inject contrast as directed by the GI doctor. The second nurse, situated near the patient's head, will monitor the patient's vital signs and administer sedation as needed. The patient will receive sedation through the IV. A combination of Versed and Fentanyl or a similar combination of medicine that creates a relaxed state and pain relief is used. The patient is in a conscious sedation state. In fact, the sedation can be so heavy that the patient may not breathe well enough to keep their oxygen levels up. During the procedure, the oxygen saturation rates will be closely monitored. If the oxygen level drops low, oxygen rates may be increased. If the oxygen level drops dangerously low, drugs can be administered to reverse the sedation. In extreme cases when the patient cannot be aroused, Narcan or Romazicon can be given. Narcan works to reverse the pain medication, Fentanyl. Romazicon works to reverse the sedative medicine, Versed.

The back of the patient's throat will be sprayed with a local anesthetic, and a mouth guard is placed to protect the patient's teeth and the endoscope. The side-viewing endoscope is introduced orally. The GI doctor views the esophagus and stomach as the tube is advanced. Air will be introduced in the stomach to allow the endoscope to be more easily manipulated into the duodenum. This will cause discomfort for the patient, more of a pressure than pain. When the pylorus is visualized, the endoscope is advanced and the tip of the scope will be slightly raised. The pylorus will be lost from view at this time due to the side viewing endoscope, thus it may take several attempts to gain access into the duodenum. The GI doctor will advance the endoscope and turn the entire scope to the right in order to get the endoscope to fall into the duodenum. Occasionally external pressure on the abdomen is applied to direct the endoscope into the duodenum.

Once in the duodenum, the Kerckring's folds come into view as air is introduced into the duodenum. The endoscope is advanced past the Papilla of Vater, until the endoscope is lying with the tip in the descending duodenum. At this time, the pressure the patient was feeling will ease up, making the patient more comfortable. The endoscope is then pulled back to remove as much of the excess scope as possible without losing sight of the Papilla of Vater. Once the endoscope is in good position, the Technologist will take a scout exposure of the RUQ. The scout should have the spine as the medial border and the other border should demonstrate the lateral aspect of the patient. The endoscope tip should be positioned a few centimeters from the bottom of the field of view. This will leave enough of the liver visible for the procedure, even during magnification views.

The Ampulla of Vater as seen through the endoscope. Notice the dilation of the bowel. This is done with air administered through the endoscope in order for the GI doctor to be able to better manipulate equipment.

Once the scope is in good position, the doctor will usually lock the endoscope, which will help the doctor maintain the optimal position. The assisting nurse passes a thin catheter through the end of the endoscope. Once the catheter is visualized at the tip of the endoscope, the nurse will flush a few cc's of water-soluble x-ray contrast, preferable non-ionic contrast, through the catheter. Fluoroscopy will be needed at this time to confirm the contrast is flushed through the catheter. Flushing the catheter helps eliminate the introduction of air into the biliary ducts. Air bubbles look similar to stones under fluoroscopy, thus flushing the catheter is essential.

The scout radiograph, notice the bowel gas pattern created by the air. This x-ray will include the entire biliary system when it is filled with contrast. Thus, allowing the technologist to lock the fluoroscopy tower and limiting the fluoroscopy exposure.

Then the GI doctor manipulates the catheter to the papilla of Vater. It is easier to cannulate the pancreatic duct because it is straight in from the papilla, and the common bile duct is slightly angled to the side. The GI doctor may ask the assisting nurse to give him a bow on the papillotome (catheter). This will cause the end of the catheter to turn up more toward the common bile duct. Injection of the pancreatic duct is not recommended because of the high probability of pancreatitis. Thus, contrast should never be injected without the guidance of fluoroscopy. The rule of thumb is to have fluoroscopy on during the injection of contrast, the manipulation of guide wires, balloon catheters, stone baskets, brushing, biopsies, and stent placement. The Radiologic Technologist should maintain a close visualization on the endoscopic images. When the technologist has the fluoroscopy on only when deemed necessary, it can reduce the fluoroscopy time, and the radiation exposure to the patient and medical staff.

The nurse will slowly inject contrast upon request of the GI physician. Injection of contrast and fluoroscopy are stopped when the common bile duct is not visualized. The GI doctor will adjust the catheter and inject again. It may take several unsuccessful attempts to introduce the catheter into the papilla. If the catheter is unable to be introduced into the common bile duct, the GI doctor may attempt to introduce a guide wire into the opening instead. The guide wire has a much smaller diameter then the catheter, thus it may be easier to get into the papilla.

Notice on the drawing the endoscope is in the duodenum, at a level where the catheter has a short distance to the Ampulla of Vater. When the catheter is in the ampulla it must go straight in then bend upwards to the common bile duct. The pancreatic duct is straight in, thus it is easily cannulated. Once inside the ampulla the GI doctor will ask for the catheter to be bowed, which means to curve the end upward toward the common bile duct.

There are several types of catheters and guide wires available for the GI doctor, and during the procedure, several catheter and guide wire combinations may be utilized before cannulation of the Ampulla of Vater is successful. A small stone may be at the opening and restrict the catheter from being introduced, or a tumor may be causing the opening to be misaligned, thus creating a more difficult and unusual route for the catheter to follow. If the papilla has been irritated by the passing of a stone it may be swollen and impede the introduction of the catheter. Throughout the process of introducing the guide wire, it is vitally important that fluoroscopy be utilized. It is vital that the pancreatic duct does not get irritated, and that there is no perforation of the organs. If the guide wire is used to enter the common bile duct, the catheter is directed up the duct right over the guide wire. Once the catheter is placed into the common bile duct, inside the papilla of Vater the injection of contrast is made. This retrograde injection is done under fluoroscopy. Spot films are taken during the injection upon the request of the doctor.

At this time, the diagnosis is easily made, and treatment options are considered. If stones are visualized, a sphincterotomy is commonly performed before stone extractions are attempted. The number of stones and the size of the stones and the inflammation of the papilla of vater determine this. If the GI doctor feels that, the Papilla of Vater could be irritated or inflamed by the extractions of stones, it is best to place a stent in the common bile duct prior to the completion of the procedure. Swelling of the papilla of Vater would restrict the flow of bile in the same manner as a stone would.

SPHINCTEROTOMY

The reasons to perform a sphincterotomy are:

Residual or recurrent common bile duct stones following cholecystectomy.

Biliary pancreatitis.

Papillary stenosis due to a tumor or scarring.

To facilitate the placement of a stent.

Common bile duct stones in high-risk surgical patients with intact gallbladders.

After it is determined that a sphincterotomy is needed a papillotome (a catheter with a steel wire that is manipulated to different bowed angles) is inserted into the endoscope if one is not already there. A grounding pad should already be placed on the patient's buttocks or a similar area that has more adipose tissue. The grounding pad is connected to the high-frequency cauterizer, and a second wire from the cauterizer is attached to the endoscope. The papillotome must be placed in the common bile duct for several millimeters; this may be checked under fluoroscopy. The papillotome is slowly withdrawn until the tip of the wire is seen. The GI doctor will usually request that a combination of cutting and coagulation frequencies that are set on the electric cauterizer. A pure cut would cause more edema at the Ampulla of Vater, but would limit the chance of bleeding. A pure coagulation cut would reduce edema, but would increase the chance of bleeding. That is why a combination of cutting and coagulation frequencies is commonly used.

The Ampulla of Vater is open after the sphincterotomy. Notice the opening diameter is greatly increased from before. Before any sphincterotomy is performed, the INR should be checked if there is any chance that excessive bleeding may occur.

The GI doctor will place the wire at the ten o'clock position to start cauterizing. The ten o'clock position decreases the chance of bleeding, because there are no major veins or arteries there, and there is no nerve ending that may cause pain for the patient. There is no required length that the sphincterotomy must be, but frequently the GI doctor will make sure that the papillotome can slide out of the duct easily in the full bowed extension without resistance (1/4-1/2 inch long). This is usually an adequate diameter for stones to be extracted or a stent to be placed.

STONES

Extraction of stones from the bile duct is probably the most common reason to do an ERCP. The stones are usually visualized on the initial injection of contrast. Frequently, the patient's ducts are dilated. Depending on the size, location, and number of stones present, the GI doctor will start the process of removing stones from the ducts.

A guide wire will be placed in the upper branches of the common bile duct; fluoroscopy will be needed at this time to insure that the guide wire is going in the right direction, and to determine when it is beyond the stone. The GI doctor does not usually attempt to remove all of the stones at once, because that may cause the stones to build a damming effect.

Notice inside the catheter is a black and yellow striped guide wire, this guide wire stays in the common bile duct as the balloon catheter is manipulated. Notice the arrow pointing at a stone that was removed from the common bile duct by the balloon catheter. This stone will pass through the intestines and will be expelled.

Once the guide wire is properly placed, the assisting nurse will "pull" a balloon catheter up the guide wire. To pull something up means that the nurse will keep the guide wire in place and advance something else over the guide wire. Fluoroscopy is needed at this time to determine when the balloon has reached the optimal distance up the duct and that the guide wire is still in the proper location. The balloon is then inflated, and the balloon is slowly pulled down the duct and out the papilla. This may or may not remove the stone depending on the size of the duct. If the duct is very dilated, the balloon may slip right past the stone. The balloon may make this trip several times, and the use of fluoroscopy will be used throughout this process, each time the balloon will travel farther up the duct. The stones removed can be any number of shapes or sizes. If the balloon is too small to act as a dam behind the stone, then a stone basket may be used.

Notice the large stone in the stone basket and the extreme dilation caused by the obstruction. This stone was unable to be removed through the endoscope, thus the patient had to undergo surgery in order to relieve the obstruction.

The GI doctor will advance the stone basket over the guide wire up to the stone and then have the nurse open the basket by releasing the tension on the handle. Then the basket will be wiggled up and down the duct to try to snare the stone. Fluoroscopy will be used at this time, to insure that the stone is caught in the basket. Once the stone is lodge in the basket, the nurse will tighten the tension on the basket, then the doctor will slowly pull the stone basket and stone from the duct. Fluoroscopy is used during this process, in order to insure that the stone is still lodged in the basket. The doctor may have to repeat this process if there is more than one stone. Occasionally, the doctor may return to using the balloon catheter to remove smaller stones or stones that seem to be crushed by the stone basket.

STENT PLACEMENT

Common Bile Duct Stent

Pancreatic Stent

A stent may be placed in the pancreatic duct, common bile duct, or occasionally both ducts. There are two types of stents placed in the ducts, plastic and metallic. The most commonly placed stent is made from plastic (polyethylene). They tend to clog up over time and may require an additional ERCP to remove or replace the stent. The plastic stent may also be used to keep the duct open if there appears to be a lot of swelling around the Papilla of Vater. The metallic stents are permanent thus; they are usually used when the duct is being restricted by a tumor.

The GI doctor will pass the stent down the endoscope tube. Once the stent is visualized by the endoscope, the doctor will ask for fluoroscopy to insure the location of the stent is correct. Besides fluoroscopy, the plastic stents may have black stripes that allow a visual queue of how much of the stent is in the duct. This is vitally important during placement of metal stents. The metal stent needs to be placed correctly because once the stent is released from the endoscope it expands. It is extremely difficult to adjust the placement of a metal stent once it has been deployed. The GI doctor needs fluoroscopy to insure that the stent extends past the stricture.

A pancreatic stent and a common bile duct stent.

Routinely the plastic pancreatic stent will be placed to keep the pancreatic duct open due to inflammation that occurs to the pancreas. Injecting the pancreatic duct while trying to locate the common bile duct or stones can cause enzymes to build up in the pancreas. In the case of cancer, a metal stent may be placed in order to keep the duct open and relieve the patient of pain. When the GI doctor is placing the pancreatic stent, fluoroscopy will be needed. The fluoroscopy assures that the stent is going into the pancreatic duct and not the common bile duct.

The placement of a plastic or temporary stent in the common bile duct is common practice after a sphincterotomy to insure that the duct will not close down again and to increase drainage from the bile duct. Frequently the temporary stents are removed without fluoroscopy guidance, because the GI doctor is able to see the stent with the endoscope, and once the stent is removed, the doctor is able to visualize drainage. Occasionally the doctor will need fluoroscopy for the removal of a temporary stent, but it is not for guidance in the removal of the stent, instead the doctor will use it to further evaluate the ducts.

A long stent that transverses the entire length of the common bile duct.

A plastic stent may also be placed if there is a leak at the post surgical site of a gallbladder removal. Occasionally there will be a leak of bile at the site of the sutures. If this happens the patient will have a lot of pain, thus, an ERCP will be ordered and if a leak is discovered, the placement of a temporary stent will allow the surgical site to heal. The stent will allow the bile to by-pass the cystic duct completely, thus removing the possibility of bile aggravating the surgical site.

STRICTURES

Most of the strictures found during an ERCP are caused by a tumor pressing on the duct walls causing the diameter to be too small to allow secretions to transverse the duct system. Routinely the GI doctor suspects a tumor prior to discovering it under fluoroscopy. The GI doctor will take sample tissue from the stricture to send to pathology when a specific diagnosis has not been made. There are two ways that tissue samples are taken: brushing and biopsy.

Brushing is a simple process where the GI doctor advances a guide wire past the stricture, then advances a brush up to the stricture. The brush looks similar to a mascara brush, small teeth on all sides. The brush is left inside a protective sheath until it is located at the stricture. At that time, the GI doctor will have the assisting nurse extend the brush from the sheath. The doctor will move the brush up and down the stricture several times before it is pulled back into the protective sheath. Fluoroscopy will be used to make sure the brush is located at the stricture and then during the brushing process itself. This is done to insure that the cells extracted onto the brush are from the stricture and not healthy tissue on either side of the stricture. The assistant will pull the brush and the protective sheath completely from the endoscope. Once the brush is removed from the endoscope, it will be cut off the wire and placed in a formalin solution to be sent to pathology.

In this film, you will notice a guide wire that is positioned above the stricture, and a biopsy forceps located at the stricture in the open position. Notice the little claw end on the biopsy forceps.

The biopsy is performed in a similar manner as the brushing. The assistant will advance a small biopsy forceps over the guide wire to the stricture. Fluoroscopy will once again be needed to help the GI doctor visualize when the forceps is located at the stricture. The assistant will open the forceps as the doctor advances it to the stricture walls. The doctor will have the assistant close the forceps tightly, and then pull back the biopsy forceps. If the doctor feels a resistance, than it is assumed that tissue was taken, the assistant will remove the forceps from the endoscope. The tissue sample will then be placed in a formalin solution to be sent to pathology. This process may be done several times until the doctor feels that enough tissue has been taken. Fluoroscopy will be needed each time to insure that the tissue is being taken from the stricture.

Spot Films

Four spot films should be taken for all ERCP's:

The scout radiograph that demonstrates the anatomy without contrast.

The initial cholangiogram that helps make the diagnosis and the treatment plan.

The post procedure cholangiogram is used to demonstrate the completion of the procedure after the removal of stones and/or stent placement.

The drainage film is taken to verify that the ampulla of the vater is draining contrast freely and to visualize the section of the common bile duct that was obscured by the endoscope.

These are the minimum films required for the Radiologist to adequately read the ERCP. The GI doctor may ask for additional films during the course of the procedure if they feel this will assist the Radiologist with the interpretation of the exam. The ERCP would not have evolved to its status without the assistance of the Radiologic Technologist. Without the use of fluoroscopy and our technical guidance, the GI doctor would be unable to perform this exam. Remember it is not just an ERCP; it is a vital procedure that will enhance the patients' life, and without the Radiologic Technologist, the procedure would not have been possible.

Summary

The ERCP is an endoscopic procedure that utilizes retrograde filling of the bile duct systems with contrast under fluoroscopy guidance.

The liver is the largest organ in the biliary system. Its main function is to break down harmful substances absorbed from the intestines.

Abnormalities of liver functions fall into one of two categories. One category is dysfunction of liver cells such as cirrhosis or hepatitis. The other category is the main reason for performing an ERCP, an obstruction of the bile flow from the liver through the biliary tract.

Bile flows through the right and left hepatic ducts, which are joined by the cystic duct and transport the bile to the small intestine.

The cystic duct connects the gallbladder to the common bile duct.

The gallbladder is responsible for the storage of bile until it is needed to aid in digestion. Food in the duodenum triggers the gallbladder to contract and release bile.

The pancreas contains two tissue types: the acini and the islets. The acini produce digestive enzymes, and the islets produce the hormones insulin, somatostatin, and glucagon.

The PD is also known as the Duct of Wirsung, transports secretions from the pancreas to the small intestines.

The papilla of vater is the small opening in the duodenum that drains the secretions from the common bile duct and pancreatic duct. It is also referred to as the Ampulla of Vater.

Stones are produced when cholesterol or bilirubin settle out of the bile, crystallize, and group together. In the U.S., almost 80% of patients with gallstones have cholesterol gallstones.

The most common risk factors for forming gallstones include being female, over forty, obese, eat a Western diet, and a genetic predisposition. Untreated obstruction of the bile ducts can result in an infection in the liver, bile ducts, or the pancreas.

Philippe Bozzine demonstrated the first endoscope in 1806 at Vienna. It consisted of a simple silver tube, which at one end was lighted by a candle, and a mirror reflected the light. 

In 1877, Max Nitze fabricated the endoscope, which looked very much like a modern rigid endoscope commonly used in the operating room today.

Ludwig Demling and Meinhard Classen performed the first ERCP in 1973. The fiber optics in today's scopes not only emits light, but also transmits images back to a monitor. 

Endoscopes are designed to either view anatomy directly in front of the scope or they can be angled to view the sides of the anatomy. For ERCP's the side viewing scope is used in order to visualize the papilla of vater.

There are numerous reasons that the GI doctor may order an ERCP. The most common symptoms that a patient presents with are abdominal pain and jaundice. 

Other symptoms include nausea, vomiting, and if an infection is involved the patient may also have a fever.

A RUQ ultrasound, CT of the abdomen, or Magnetic Resonance Cholangio Pancreatiogram (MRCP) may have been done previously, which indicated the need for an ERCP. 

Bilirubin is a component of the bile produced by the liver.

A prothrombin time may also be done to determine the clotting time of the blood. 

Non-ionic tri-iodinated x-ray contrast is the contrast of choice.

The ERCP does have a 10% chance of complication, but the risk drops to 2-5% when a sphincterotomy is not performed. Severe complications occur only 1-2% of the time.

Pancreatitis is the most common complication, which is caused by irritation to the pancreatic ducts.

Bleeding is another complication, which may occur after a sphincterotomy, the removal of stones, or the placement of a stent. The bleeding usually stops without medical intervention, but an injection of Epinephrine at the hemorrhaging site could be used to stop bleeding.

The most severe risk during an ERCP is the perforation of the bowel wall or bile duct.

The patient is then placed on the fluoroscopy table in the left anterior oblique (LAO) position,

A combination of Versed and Fentanyl or a similar combination of medicine that creates a relaxed state and pain relief is used to create a conscious sedation state. 

In extreme cases when the patient cannot be aroused, Narcan or Romazicon can be given.

Air will be introduced in the stomach to allow the endoscope to be easily manipulated into the duodenum. This will cause discomfort for the patient, more of a pressure than pain.

The endoscope is advanced past the Papilla of Vater, until the endoscope is lying with the tip in the descending duodenum.

Air bubbles look similar to stones under fluoroscopy, thus flushing the catheter prior to placement in the duct is essential.

It is easier to cannulate the pancreatic duct because it is straight in the papilla, and the common bile duct is slightly angled to the side.

The GI doctor may ask the assisting nurse to give him a bow on the papillotome (catheter). This will cause the end of the catheter to turn up more toward the common bile duct.

Injection of the pancreatic duct is not recommended because of the high probability of pancreatitis. 

Swelling of the papilla of Vater would restrict the flow of bile in the same manner as a stone would.

A papillotome is a catheter with a steel wire that is manipulated to different bowed angles which allows the GI doctor to cauterize.

If the catheter is unable to be introduced into the common bile duct, the GI doctor may attempt to introduce a guide wire into the opening instead. The guide wire has a much smaller diameter then the catheter, thus it may be easier to get into the papilla.

The GI doctor will usually request that a combination of cutting and coagulation frequencies that are set on the electric cauterizer. A pure cut would cause more edema at the Ampulla of Vater, but would limit the chance of bleeding. A pure coagulation cut would reduce edema, but would increase the chance of bleeding.

The GI doctor will place the wire at the ten o'clock position to start cauterizing. The ten o'clock position decreases the chance of bleeding, because there are no major veins or arteries there, and there is no nerve ending that may cause pain for the patient. 

Extraction of stones from the bile duct is probably the most common reason to do an ERCP.

If the balloon is too small to act as a dam behind the stone, then a stone basket may be used.

A stent may be placed in the pancreatic duct, common bile duct, or occasionally both ducts. 

The most commonly placed stent is temporary and is made from plastic (polyethylene).

The metallic stents are permanent thus; they are usually used when the duct is being restricted by a tumor.

The initial placement of a metal stent must be correct, because once the stent is released from the endoscope it expands in both diameter and length.

A plastic stent may also be placed if there is a leak at the post surgical site of a gallbladder removal.

Once the brush is removed from the endoscope, it will be cut off the wire and placed in a formalin solution to be sent to pathology.

Four spot films should be taken for all ERCP's, the initial scout, the initial cholangiogram, the post procedure cholangiogram, and the drainage film.

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