What is a cholangiogram?
A cholangiogram is a diagnostic test used to evaluate the gallbladder and bile ducts, which is the ductal system that connects the liver, pancreas, and gallbladder with the intestine. Bile refers to the greenish-brown fluid made that aids digestion and is secreted by the liver and stored in the gallbladder. A cholangiogram can be done in several different ways and often uses X-rays and a radiopaque contrast medium to opacify the ductal system.
Bile ducts consist of intrahepatic (within the liver) and extrahepatic (outside of the liver) ducts which can get obstructed for various reasons.
Cholangiography refers to the imaging of the ducts but can be done in several different ways:
- Intravenous cholangiography – Contrast is given through a vein in your arm. Contrast then concentrates in the bile ducts as it is secreted by the liver. This outlines the larger more central bile ducts and can aid in identifying a site of obstruction and serial x-rays are obtained. This methodology has fallen out of favor because it can often fail to adequately outline the bile ducts and the gallbladder.
- MR Cholangiogram: Contrast is administered intravenously as above (Some methods allow for imaging even without contrast administration) and then an MRI of the liver and bile ducts is obtained. This method allows for great visualization of the bile ducts and the gallbladder. Much like IV cholangiography above MR cholangiography is a diagnostic test that allows for visualization of pathology but will not actually treat an obstruction.
- Percutaneous transhepatic cholangiography : The contrast is administered directly into the liver through a small puncture through the with a fine needle in the abdominal wall. This is performed under moderate sedation and is generally used when other types of cholangiography cannot be performed of when ERCP (Below) fails and intervention such as drainage of the bile ducts is needed. If adequate percutaneous transhepatic cholangiogram images are obtained there is an option to place a percutaneous biliary drain to drain an obstructed bile duct.
- Endoscopic retrograde cholangiopancreatography: A scope is placed through the mouth down the esophagus and through the stomach into the duodenum. The natural orifice of the bile duct which empties into the duodenum is then entered and contrast is given through a tube that is delivered directly from the mouth to the bile ducts. This is the most widely used technique for obtaining cholangiographic images and also allows for placement of biliary stents for drainage of an obstruction.
When is a cholangiogram requested?
Cholangiography is usually ordered in people who have suffered biliary colic, pancreatitis, have yellowing of the skin (jaundice) or have pain in the upper right part of the abdomen, have a known obstruction of a bile duct and in those who after having an ultrasound (a test that can show biliary ductal dilatation) some anomaly is observed that raises suspicion for some pathology related to the bile duct: biliary ductal dilation, a stone that obstructs the outflow of bile or a bile duct tumor. Endoscopic retrograde cholangiography can also be indicated when you want to evaluate the pancreatic duct as well as the bile ducts.
Preparation for cholangiogram
- The patient must fast from the night before or at least 6 hours before the ERCP. You will only be able to drink sips of water if you have to take any regular medication.
- Additionally, it is essential to discuss your health issues in their entirety with your doctor. Some medications can be held while others, especially those in patients with heart prosthesis or pacemaker which interfere with blood clotting (Heparin, warfarin…. etc.) have to be considered before any procedure. Additionally prior allergic reactions to any drug or contrast should be discussed.
- Women must be sure that they are not pregnant, because X-rays are used in most instances and should generally be avoided during pregnancy given the risk to the fetus.
- Patients using dentures should remove them prior to testing.
- The patient must sign an informed consent document explaining what the medical test consists of, what its risks and objectives are, and what alternatives exist.
- Most cholangiograms are performed under moderate sedation which means that the patient is sedated and may even fall asleep but can be woken up and is responsive. On occasion the procedure is performed under general anesthesia.
- Usually, the patient is instructed to take before performing the cholangiopancreatography, an antibiotic treatment to reduce the risk of complications from infection (pancreatitis, etc.)
Contraindications to cholangiography
Cholangiography when performed as ERCP, Percutaneous cholangiography, IV cholangiography uses ionizing radiation (X-Rays) and contrast medium. MRI cholangiogram does not use ionizing radiation but can use contrast. Because of these reasons pregnant patients or patients with renal dysfunction should discuss their risks with their physician.
Additionally patients taking metformin and receiving intravenous contrast medium such as with IV cholangiography or percutaneous transhepatic cholangiogram should stop taking it per the practitioners protocol.
What are the risks of a cholangiogram?
Adverse effects may be due to allergies to iodinated contrast or the development of acute renal failure due to contrast, both rare complications, generally in people with previous kidney problems.
Endoscopic retrograde cholangiography has a risk of producing pancreatitis as a reaction to contrast injected backward from the common bile duct. In addition, if a therapeutic procedure is performed, there is a risk of intestinal bleeding or intestinal perforation.
How is a cholangiography performed?
The test is usually performed after the patient is admitted to hospital but can also be performed on an outpatient basis.
Before starting the test, a sedative drug is administered intravenously, so that the patient is more comfortable, producing a state of drowsiness.
ERCP test is started by orally introducing a duodenoscope, a thin and flexible tube with a camera and light at its end and lateral vision, passing through the esophagus, the stomach until it reaches the first portion of the small intestine, the duodenum.
Through the duodenoscope, tools can be inserted that allow samples to be extracted for analysis or treatment. The common bile duct and pancreatic duct flow into the duodenum. It is common to make a small cut (sphincterotomy) to facilitate access to the ducts with a cannula (another small tube) through which a contrast is injected. This contrast enhances the tissues in their visualization by obtaining X-ray images, with which the endoscopist can detect if there is any type of alteration in them and perform, if necessary, the therapeutic techniques that must be applied.
The duration of endoscopic retrograde cholangiography ranges from 45-60 minutes.
Percutaneous transhepatic cholangiography on the other hand is performed by advancing a fine needle puncture into the liver. The needle is passed through the abdominal wall in the upper upper quadrant, in order to inject the contrast directly into the biliary tree through the liver. Thus, the bile ducts are visualized through X-ray imaging tests.
What is an MRI cholangiogram?
MR cholangiogram is a non-invasive diagnostic imaging test, which allows visualizing of the ducts, through the use of radiofrequency waves, images of the bile duct, gallbladder, pancreatic duct and pancreas.
MR cholangiography can be performed with or without contrast.
What is an ERCP?
ERCP or Endoscopic Retrograde Cholangiopancreatography is a diagnostic test that visualizes the bile ducts, gallbladder, pancreatic duct and pancreas by performing an endoscopy, that is, the introduction of a small flexible tube with a camera at its end (endoscope) through the mouth.
Through this tube, a small cannula can also be introduced which, once the area where the pancreatic duct and the bile duct open (Vater’s ampulla) is located, is inserted into it. Through the cannula, a contrast is administered that diffuses through all the ducts and, by performing a static or dynamic X-ray, these ducts and their possible alterations are seen in images.
What is intraoperative cholangiography?
Intraoperative or peroperative cholangiography is the one that It is performed during the surgical procedure, by injecting a contrast directly into the bile ducts to study the biliary tree.
What is a papillotomy?
A papillotomy is an incision (cut) that is made in a part of the small intestine (duodenal papilla) to remove a gallstone (stone) from the bile duct, when it has been identified obstructing the duct by means of an ERCP.
What is an endoscopic sphincterotomy?
Endoscopic sphincterotomy is the making of an incision (cut) of the sphincter of Oddi ( exit of the bile duct and the pancreatic duct to the duodenum).