ERCP or MRCP: Treatment for Biliary Obstruction
To truly understand what Magnetic Resonance Cholangio-Pancreatography (MRCP) and Endoscopic Retrograde Cholangio-Pancreatography are, you first must understand what a biliary obstruction is and what typically causes this type of problem.
While gallstones often trigger a biliary obstruction, there are many reasons why a biliary obstruction might occur and many ways to treat those issues that will depend on the patient’s age, overall health, anatomy, history of digestive system issues, and other considerations that can vary from person to person.
Biliary Obstruction Explained
Let’s start with how the digestive system works. To obtain the maximum possible nutrients from food, food must be broken down by the digestive tract so all of the vitamins, minerals, proteins, fats, and carbohydrates can be absorbed by the small intestine. This process starts with chewing food, followed by the stomach using acids and sloshing the food around to help break it down. After that, bile is added to the food to break down the fatty portion of the meal.
Bile is a digestive juice that is made in the liver and can be used immediately or stored for later use. If the bile will be used later, it will travel from the liver into the gallbladder through one of the bile ducts—tubes that transport bile away from the liver to where it is used to aid digestion.
If the bile will be used immediately after leaving the liver, it will flow from the liver directly to the first part of the small intestine (the duodenum) via the common bile duct. About fifty percent of bile is used immediately in this manner while the other half waits in the gallbladder, where most of the water is removed and the bile becomes more concentrated.
When bile is unable to move through one of the bile ducts from the liver or gallbladder due to a problem with the ducts, this is called a biliary obstruction. The most common type of biliary obstruction is the gallstone, which is a ball of bile that hardens during the process of removing water from bile, which is one of the functions of the gallbladder. These small stones get trapped in the gallbladder or in the duct that takes bile from the gallbladder to the duodenum.
When these stones block a duct, the results can range from mild to severe in intensity and can start suddenly and unexpectedly. Once they start, they can reoccur frequently and often will seem triggered by food.
- Gallstones (this is the most common cause of biliary obstruction)
- Abnormal narrowing of one of the bile ducts, commonly called biliary stenosis
- Bile duct inflammation
- The formation of a cyst in one of the ducts
- Lymph node enlargement that compresses the duct from the outside
- Pancreatitis, especially recurring or chronic
- Injury/trauma that involves the liver, gallbladder, pancreas or bile ducts
- Tumors, cancerous or benign
- Infection of the gallbladder, bile ducts or pancreas
- Liver disease
There are many reasons why a person would experience a biliary obstruction, some of the more common causes are:
- History of gallstones
- History of surgery that affects the bile ducts
- History of biliary cancer
- History of liver cancer or disease
- History of pancreatic cancer or disease
- History of gallbladder problems
- Recent history of surgery to remove the gallbladder
- Chronic pancreatitis
- Rapid weight loss
Signs and Symptoms
The signs and symptoms of a biliary obstruction will vary from individual to individual, but typically include one or more of the following:
- Abdominal pain, typically in the right upper abdomen
- Jaundice (yellowing of the skin)
- Nausea and Vomiting
- Clay or white colored bowel movements
- Dark urine
If a biliary obstruction is suspected, there are blood tests, imaging studies, and procedures that can be done to confirm the diagnosis.
Common blood tests that would indicate a possible bile duct problem include increased alkaline phosphatase level, an elevated bilirubin level, and increased liver enzymes. A problem that causes bile to back up into the liver will cause dramatic changes in blood tests that check liver function.
Additional tests that can be done to diagnose a biliary obstruction include:
- Ultrasound of the abdomen
- CT scan of the abdomen
- Percutaneous transhepatic cholangiogram (PTCA)
- Magnetic Resonance Cholangio-Pancreatography (MRCP)
- Endoscopic Retrograde Cholangio-Pancreatography (ERCP)
Treatments that can be done to treat biliary obstruction are dependent on the cause and location of the problem. The most common cause is a gallstone, and treatments include the Endoscopic Retrograde Cholangio-Pancreatography (ERCP) and surgery to remove the gallbladder (cholecystectomy).
If the cause of the obstruction is something other than a gallstone, the treatment may vary widely from person to person. For example, a person who is experiencing a biliary obstruction due to cancer will be treated very differently than a person who is experiencing the same problem due to infection. The elderly patient with gallstones may receive different treatment than the 30-year-old woman who is experiencing the same signs and symptoms, as the older patient may not be able to tolerate the same treatment as the younger one.
Typically, the least invasive method of diagnosing and treating is the first to be attempted—such as MRCP—while a more invasive procedure like an ERCP or gallbladder surgery is performed only if necessary. That said, gallbladder surgery, also known as cholecystectomy, is one of the most common surgeries performed in the United States.
Magnetic Resonance Cholangio-Pancreatography (MRCP)
Magnetic Resonance Cholangio-Pancreatography, commonly known as MRCP, is a non-invasive test much like a standard MRI. This test is used to examine the liver, pancreas, gallbladder, and bile ducts to determine if an obstruction is present. The test can help diagnose an obstruction, and can also help determine the cause of the obstruction, which can determine how the issue should be treated.
When Is MRCP Performed?
An MRCP is performed when there is a suspicion that a bile duct obstruction is present and causing an issue. Not only can this test determine if a bile duct obstruction is present, this test can often determine what is causing the issue. Unfortunately, while the MRCP is a great way to diagnose the problem, this test can only help determine how to best treat the issue—the MRCP itself cannot treat the obstruction.
What Happens During MRCP?
During the MRCP the patient is required to be still on a bed that moves in and out of the tube-like MRI machine. The test is non-invasive, meaning that nothing is placed on or in the body. Like an x-ray, the machine does not have to touch you to examine the inside of the body. The test is a noisy one but usually takes only 15 to 20 minutes to perform.
Risks of MRCP
The risks of MRCP are minimal. Patients who experience claustrophobia or are very heavy may require the less common open MRI machine for their study rather than the traditional tube-like machine, but there are no significant risks with this type of study. If contrast medium is used, there is a small risk of allergic reaction, and contrast should be used with caution in patients with kidney problems.
Patients with metal implants can only have an MRCP if their implant is MRI safe, as the process uses a very strong magnet to create images of the inside of the body. There is no radiation exposure during an MRI.
Endoscopic Retrograde Cholangio-Pancreatography, more commonly known as ERCP, is an invasive procedure where a lighted endoscope is inserted into the mouth and gently pushed through the esophagus into the stomach, and then into the first part of the small intestine called the duodenum.
The endoscope has both a light and a camera on the end, which allows the physician to visually inspect the inside of the digestive tract. This is possible because the common bile duct empties into the duodenum, and if a gallstone or another obstruction is present in the bile duct, a skilled gastroenterologist can often remove the stone using a wire, basket or balloon attachment on the endoscope.
When Is ERCP Performed?
The ERCP is performed for one of two reasons. The first reason is to make a diagnosis—to determine if a biliary obstruction is present by visually inspecting the duct. The second reason an ERCP is performed is when other studies, such as blood tests or an MRCP, indicate that a biliary obstruction is not only present, but the problem can be fixed by placing a stent or removing a gallstone from the bile duct.
Unlike the MRCP, which gives images of what is happening in the body, the ERCP can actually treat the problem.
Risks of ERCP
While the ERCP is considered a low-risk procedure, like any invasive procedure there are potential complications that should be discussed. In addition to the risks associated with anesthesia, the ERCP can cause pancreatitis, infection, and bleeding.
The most severe complication is typically a perforation—accidentally making a hole with the instruments—in the intestine or other areas where the ERCP is exploring. The risk of a perforation is low in the hands of a skilled gastroenterologist, but it is nonetheless possible. When a hole is made, a surgeon is typically consulted to repair the damage and prevent further complications.
Anesthesia and ERCP
The ERCP procedure is performed with the patient receiving general anesthesia so that they are unaware of the procedure being performed. The patient will be intubated and placed on a ventilator and is asleep for the entire procedure.
When the procedure is completed, a medication will be given to stop the sedation and the patient will slowly wake up. Once the patient is able to breathe on their own, the endotracheal tube is removed and the patient is typically taken to the Post Anesthesia Care Unit (PACU) or their hospital room to recover.
This procedure may be performed as an inpatient or an outpatient procedure. If the patient is not terribly ill, they may return home the same day, while sicker patients may need to recover in the hospital.
Bile Duct Obstruction. http://www.nytimes.com/health/guides/disease/bile-duct-obstruction/overview.html