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Endoscopic, Retrograde Cholangio Pancreatography
Endoscopic refers to the use of an instrument called an
endoscope - a thin, flexible tube with a tiny video camera and light on
the end. The endoscope is used by a highly trained subspecialist, the
gastroenterologist, to diagnose and treat various problems of the GI
tract. The GI tract includes the stomach, intestine, and other parts of
the body that are connected to the intestine, such as the liver,
pancreas, and gallbladder.
Retrograde refers to the direction in which the
endoscope is used to inject a liquid enabling X-rays to be taken of the
parts of the GI tract called the bile duct system and pancreas.
The process of taking these X-rays is known as
cholangiopancreatography. Cholangio refers to the bile duct system,
pancrea to the pancreas.
Indications for imaging
- Gallstones, which are trapped in the main bile duct
- Blockage of the bile duct
- Yellow jaundice, which turns the skin yellow and the urine
dark
- Undiagnosed upper-abdominal pain
- Cancer of the bile ducts or pancreas
- Pancreatitis (inflammation of the pancreas)
The main symptoms of pancreatitis are acute, severe pain in
the upper abdomen, frequently accompanied by vomiting and fever.
The abdomen is tender, and the patient feels and looks ill. The
diagnosis is made by measuring the blood pancreas enzymes which
are elevated. A sound wave test (ultrasound) or abdominal CT
exam often shows an enlarged pancreas. The condition is treated
by resting the pancreas while the tissues heal. This is
accomplished through bowel rest, hospitalization, intravenous
feeding and, pain medications.
When pancreatitis is caused by gallstones, it is necessary to
remove the gallbladder. This is usually done after the acute
pancreatitis has resolved. At times, an ERCP (Endoscopic
Retrograde CholangioPancreatography) test is recommended. This
involves passing a flexible tube through the mouth and down to
the small intestine. A small catheter is then inserted into the
bile duct to see if any stones are present. If so, they are then
removed with the scope.
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Patient Preparation
When preparing a patient for a gastrointestinal x-ray examination, every
consideration should be given to informing the patient of the
examination's purpose, the technique and duration of the procedure, and
any anticipated discomfort or risk. This prepares the patient
psychologically for the procedure and is of equal importance for the
preparation of the patient's alimentary tract for receiving the contrast
material. Optimum evaluations of the esophagus, stomach, small
intestine, and colon are done only when these organs are empty and
clean. This is the objective of the detailed and at times arduous
preparation instructions which are given to patients prior to these
examinations. These instructions should be thoroughly familiar to the
referring physician and understood by the patient.
Patients should ingest no solids for at least 6-7 hours and no
liquids for at least four hours prior to the procedure. If a gastric
emptying problem is suspected, a longer period of fasting may be needed.
If circumstances do not permit an adequate fast, lavage of the stomach
through a large bore tube can adequately remove stomach contents. For
some procedures, topical pharyngeal anesthesia alone is sufficient,
especially when the endoscopy is performed with a small diameter
endoscope. For prolonged examinations, those in children, or in patients
with a high degree of anxiety, rapid onset sedatives and/or analgesics
are often necessary. Anticholinergics (e.g., atropine) have been given
to decrease saliva, gastric secretions and motility, and perhaps reduce
the likelihood of vasovagal reactions; however, controlled studies of
their value as endoscopic premedication do not support their routine
use.(3) For procedures in which paresis of gastroduodenal motility is
necessary, parenteral glucagon may be useful
The patient is prepared as for upper gastrointestinal endoscopy.
Because of the longer duration and potential discomfort of the procedure
an intravenous line is desirable. If cannulation is delayed, or
therapeutic maneuvers prove necessary, repeated doses of sedatives or
analgesics may be needed.(8) Careful monitoring of vital signs and level
of consciousness is essential throughout and immediately after the
examination. Glucagon, with or without anticholinergics administered
intravenously will reduce duodenal motility. Use of iodinated contrast
agents for ERCP appears to be safe in individuals with a history of
systemic reactions to intravascular contrast agents.(9,10)
When an obstructed duct is suspected, most endoscopists administer
antibiotics intravenously prior to the ERCP, and continue antibiotics
for 24-48 hours if contrast has been instilled into an obstructed
system. The benefits of adding antibiotics to contrast solution has not
been proven. Depending on the indication for the ERCP, surgical support
should be available anticipating possible abdominal surgery
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Basic Proceedure
The throat is anesthetized with a spray or solution, and the
patient is usually mildly sedated. The endoscope is then gently
inserted into the upper esophagus. The patient breathes easily
throughout the exam, with gagging rarely occurring. A thin tube
is inserted through the endoscope to the main bile duct entering
the duodenum. Contrast media is then injected into this bile
duct and/or the pancreatic duct and x-ray films are taken. The
patient lies on his or her left side and then turns onto the
stomach to allow complete visualization of the ducts. If a
gallstone is found, steps may be taken to remove it. If the duct
has become narrowed, an incision can be made using
electrocautery (electrical heat) to relieve the blockage.
Additionally, it is possible to widen narrowed ducts and to
place small tubing, called stents, in these areas to keep them
open. The exam takes from 20 to 40 minutes, after which the
patient is taken to the recovery area
Side Effects and Risks
A temporary, mild sore throat sometimes occurs after the exam.
Serious risks with ERCP, however, are uncommon. One such risk is
excessive bleeding, especially when electrocautery is used to
open a blocked duct. In rare instances, a perforation or tear in
the intestinal wall can occur. Inflammation of the pancreas also
can develop. These complications may require hospitalization
and, rarely, surgery.
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
Due to the mild sedation, the patient should not drive or
operate machinery for six hours following the exam. For this
reason, a driver should accompany the patient to the exam
Contrast Media
Typical - 20 mls non-ionic/low-osmolality 200 mg/ml contrast
media
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Radiation protection~
"28 Day Rule"
Direct lead rubber waist level protection
General Fluoroscopic radiation protection / dose reduction methods
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Exposure Factors
| Kv |
mAS |
FFD (cm) |
Grid |
Focus |
AEC |
Cassette |
| 85 |
20 |
100 |
Yes |
Broad |
Yes |
18 x 24 cm |
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Image
ID and anatomical markers must be present and correct in the
appropriate area of the film.
Optimal exposure should penetrate contrast should be low enough to visualise fully the bone and
soft tissue structures.
Slightly dilated common bile duct
with calculus and normal pancreatic duct are shown
.www.amershamhealth.com
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Alternative Imaging
Alternative tests to ERCP include certain types of x-rays (CAT
scan, CT) and sonography (ultrasound) to visualize the pancreas
and bile ducts. In addition, dye can be injected into the bile
ducts by placing a needle through the skin and into the liver.
Small tubing can then be threaded into the bile ducts. Study of
the blood also can provide some indirect information about the
ducts and pancreas
Magnetic resonance cholangiopancreatography (MRCP) was first
reported in 1991 by Wallner. Since then it has become a well
recognised investigation in the non-invasive work-up of patients
with pancreaticobiliary disease including calculus disease,
chronic pancreatitis, biliary strictures, sclerosing cholangitis
and congenital disorders. It is particularly useful in
preoperative mapping of the ductal systems or where previous
surgery may have altered the anatomy e.g. laparoscopic
cholecystectomy.
Magnetic resonance cholangiopancreatography (MRCP) was first
reported in 1991 by Wallner. Since then it has become a well
recognised investigation in the non-invasive work-up of patients
with pancreaticobiliary disease including calculus disease,
chronic pancreatitis, biliary strictures, sclerosing cholangitis
and congenital disorders. It is particularly useful in
preoperative mapping of the ductal systems or where previous
surgery may have altered the anatomy e.g. laparoscopic
cholecystectomy.
MRCP is made possible by stationary fluid in the ducts producing a
high intensity signal. This can then be recognised separately from
the surrounding structures. Once the area in question has been
defined a series of thin slices 2 - 5mm thick are taken and
computer processing is applied to construct the images. The images
can be either cross-sectional (tomographic), to visualise the bile
ducts as well as surrounding structures or projectional (cholangiographic)
which produces images similar to a cholangiogram. A contrast can
be used to produce finer detail of the smaller ducts but this is
not routine. Furthermore an MR examination of the liver and
pancreas can be incorporated into the examination but again this
is not routine and it adds a considerable amount of time onto what
is otherwise a very quick examination.
There are many advantages of MRCP compared with previous imaging
techniques. It does not require the use of contrast so avoiding
the possibility of a reaction. In fact safety is comparable to
ultrasound providing the few contraindications are observed and
since no radiation is used. No special patient preparation is
required and the procedure is very rapid to perform.
When compared to ERCP or PTC the accuracy is very similar. MRCP
has a sensitivity and specificity of 91% and 98% respectively for
choledocholithiasis (1,2,3). Its accuracy for benign and malignant
obstruction is 90%. Furthermore it does not carry the 5 - 30%
failure rate associated with ERCP (4). It is also spares the
morbidity (1-7%) and mortality (0.2-1%) of ERCP (4,5) and is twice
as cost effective (5).
The disadvantage is that it is solely a diagnostic test. For this
reason it should not be used in choledocholithiasis when there is
a high likelihood of a CBD stone. In this situation ERCP would be
indicated since endobiliary therapy can also be carried out. MRCP
is not the initial investigation of choice in cholecystitis as
ultrasound is just as accurate and much more cost effective.
MRCP has many benefits when compared to other methods of biliary
imaging and will be used increasingly as MR technology becomes
more available.
MRCP is made possible by stationary fluid in the ducts producing a
high intensity signal. This can then be recognised separately from
the surrounding structures. Once the area in question has been
defined a series of thin slices 2 - 5mm thick are taken and
computer processing is applied to construct the images. The images
can be either cross-sectional (tomographic), to visualise the bile
ducts as well as surrounding structures or projectional (cholangiographic)
which produces images similar to a cholangiogram. A contrast can
be used to produce finer detail of the smaller ducts but this is
not routine. Furthermore an MR examination of the liver and
pancreas can be incorporated into the examination but again this
is not routine and it adds a considerable amount of time onto what
is otherwise a very quick examination.
There are many advantages of MRCP compared with previous imaging
techniques. It does not require the use of contrast so avoiding
the possibility of a reaction. In fact safety is comparable to
ultrasound providing the few contraindications are observed and
since no radiation is used. No special patient preparation is
required and the procedure is very rapid to perform.
When compared to ERCP or PTC the accuracy is very similar. MRCP
has a sensitivity and specificity of 91% and 98% respectively for
choledocholithiasis (1,2,3). Its accuracy for benign and malignant
obstruction is 90%. Furthermore it does not carry the 5 - 30%
failure rate associated with ERCP (4). It is also spares the
morbidity (1-7%) and mortality (0.2-1%) of ERCP (4,5) and is twice
as cost effective (5).
The disadvantage is that it is solely a diagnostic test. For this
reason it should not be used in choledocholithiasis when there is
a high likelihood of a CBD stone. In this situation ERCP would be
indicated since endobiliary therapy can also be carried out. MRCP
is not the initial investigation of choice in cholecystitis as
ultrasound is just as accurate and much more cost effective.
MRCP has many benefits when compared to other methods of biliary
imaging and will be used increasingly as MR technology becomes
more available.
MRCP info From - Royal College of Surgeons Edinburgh website |
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