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Introduction
The following is a description of the most commonly used diagnostic
tests to evaluate symptoms of conditions of the upper gastrointestinal tract.
These are general descriptions, your test experience and test preparation
instructions may be slightly different than what is outlined below.
X-rays
The upper gastrointestinal (GI) series, also referred to as a barium
swallow, is used to look for abnormalities or irregularities in the lining
of the esophagus, stomach or duodenum. It is important to avoid all food
and drink for 4-6 hours before the test to allow an accurate examination.
A series of X-rays is taken while the patient is swallowing a thick white
barium liquid and also afterwards; the patient will also swallow a medication
that produces some gas in the stomach to improve the quality of the pictures.
Using a machine called a fluoroscope, the radiologist is also able to
watch your digestive system work as the barium moves through it. This
part of the procedure can reveal problems with functioning of the digestive
system, for example, whether the muscles that control swallowing are working
properly. As the barium moves into the small intestine, the radiologist
can take x-rays of it as well. The barium, which shows up on X-rays, also
allows the radiologist to detect abnormalities such as esophageal stricture,
achalasia of the cardia (failure of the cardiac sphincter - a ring of
muscle in the stomach- to relax), hiatus
hernia, gastric ulcer, duodenal ulcer
and cancer of the esophagus or stomach. Barium
X-rays will not detect Helicobacter pylori
infection or celiac disease, for example and they do not allow biopsies
to be taken to confirm the diagnosis.
Barium X-rays are not as good as endoscopy at detecting small or early
abnormalities and, if a suspicious area is seen on the X-ray, a follow-up
endoscopy is usually required to make a firm diagnosis.
Preparation
Your stomach and small intestine must be empty for the procedure to be
accurate, so the night before you will not be able to eat or drink anything
after midnight. Your physician may give you other specific instructions.
An upper GI series takes 1 to 2 hours. It is not uncomfortable. The barium
may cause constipation and white-colored stool for a few days after the
procedure.
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Barium Meal
This section is under construction.
Radioisotope gastric-emptying scan
You will eat food that contains a radioisotope, a slightly radioactive
substance that will show up on the scan. The dose of radiation from the
radioisotope is small and not dangerous. After eating, you will lie under
a machine that detects the radioisotope and shows an image of the food
in the stomach and how quickly it leaves the stomach.
Cholecystogram or cholescintigraphy
This test evaluates the gallbladder and can be helpful in identifying
gallstones and other problems related to the gallbladder. The patient
is injected with a special iodine dye, and x-rays are taken of the gallbladder
over a period of time. (Some people swallow iodine pills the night before
the x-ray.) The test shows the movement of the gallbladder and any obstruction
of the cystic duct.
Abdominal Ultrasound
This test uses high frequency sound waves to detect abnormalities in the
liver, spleen, kidneys, pancreas, bladder, ovaries and abdominal lymph
nodes. It is also a very good way of detecting gallstones in the gallbladder.
It does not use X-rays and is safe during pregnancy. It takes only a few
minutes and is not generally painful or uncomfortable.
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Abdominal CT Scan
This uses X-rays to detect abnormalities similar to those detected by
ultrasound - abnormal areas in the liver, spleen, kidneys, pancreas, bladder,
stomach, bowel and abdominal lymph nodes.. It can be more accurate than
ultrasound in detecting small abnormalities but it is also a more complicated,
longer and more expensive test than ultrasound.
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Endoscopy
and ERCP
Endoscopy
Upper endoscopy is also called EGD, which stands for esophagogastroduodenoscopy-
as it examines the esophagus, the stomach (gastro), and duodenum- the
first part of the small bowel.
An endoscope is a long, flexible tube with a powerful light and, in most
recent instruments, a TV chip, at the tip; the endoscope also has a small
channel through which biopsy forceps (or other instruments) can be passed
so that small tissue samples (biopsies) can be taken from the lining of
the esophagus, stomach or duodenum for further testing.
Endoscopy is used to diagnose many abnormalities in the upper gastrointestinal
tract, including erosive esophagitis, Barrett's esophagus, esophageal
varices, gastric ulcer, duodenal ulcer, cancer of the esophagus or stomach
and celiac disease. Sometimes the diagnosis can be made at the time of
the endoscopy; often, the diagnosis can be confirmed only after the biopsy
specimens have been examined by a pathologist.
A number of conditions can also be treated during endoscopy: for example,
esophageal varices can be injected or 'banded' to prevent bleeding, a
bleeding peptic ulcer can be injected or cauterized to stop or prevent
bleeding, an esophageal stricture (narrowing) can be stretched to improve
swallowing and gastric polyps can be removed.
Endoscopy is a very safe procedure. An endoscopy examination takes about
10-20 minutes. In most cases, a local anesthetic throat spray will be
used to numb the throat; often, a mild sedative will be given, intravenously
('conscious sedation') to reduce anxiety.
Possible complications of upper endoscopy include bleeding and puncture
of the stomach lining. However, such complications are rare. Most people
will probably have nothing more than a mild sore throat after the procedure.
The procedure takes 20 to 30 minutes. Because you will be sedated, you
will need to rest at the physician's office for 1 to 2 hours until the
medication wears off.
Preparation
Your stomach and duodenum must be empty for the procedure to be thorough
and safe, so you will not be able to eat or drink anything for at least4-
6 hours beforehand. It is important to avoid all food and drink for at
least 4-6 hours before an endoscopy because food will obscure the view
of the stomach and it may be aspirated into the lungs if vomiting occurs.
Also, if you do receive sedation for an endoscopy, you must arrange for
someone to take you home--you will not be allowed to drive because of
the sedatives. Your physician may give you other special instructions.
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ERCP
Endoscopic retrograde cholangiopancreatography (ERCP) enables the physician
to diagnose problems in the liver, gallbladder, bile ducts, and pancreas.
The liver is a large organ that, among other things, makes a liquid called
bile that helps with digestion. The gallbladder is a small, pear-shaped
organ that stores bile until it is needed for digestion. The bile ducts
are tubes that carry bile from the liver to the gallbladder and small
intestine. These ducts are sometimes called the biliary tree. The pancreas
is a large gland that produces chemicals that help with digestion.
ERCP may be used to discover the reason for jaundice, upper abdominal
pain, and unexplained weight loss. ERCP combines the use of x-rays and
an endoscope, which is a long, flexible, lighted tube. Through it, the
physician can see the inside of the stomach, duodenum, and ducts in the
biliary tree and pancreas.
For the procedure, you will lie on your left side on an examining table
in an x-ray room. You will be given medication to help numb the back of
your throat and a sedative to help you relax during the exam. You will
swallow the endoscope, and the physician will then guide the scope through
your esophagus, stomach, and duodenum until it reaches the spot where
the ducts of the biliary tree and pancreas open into the duodenum. At
this time, you will be turned to lie flat on your stomach, and the physician
will pass a small plastic tube through the scope. Through the tube, the
physician will inject a dye into the ducts to make them show up clearly
on x-rays. A radiographer will begin taking x-rays as soon as the dye
is injected.
If the exam shows a gallstone or narrowing
of the ducts, the physician can insert instruments into the scope to remove
or work around the obstruction. Also, tissue samples (biopsy) can be taken
for further testing.
Possible complications of ERCP include pancreatitis
(inflammation of the pancreas), infection, bleeding, and perforation of
the duodenum. However, such problems are uncommon. You may have tenderness
or a lump where the sedative was injected, but that should go away in
a few days or weeks.
ERCP takes 30 minutes to 2 hours. You may have some discomfort when the
physician blows air into the duodenum and injects the dye into the ducts.
However, the pain medicine and sedative should keep you from feeling too
much discomfort. After the procedure, you will need to stay at the physician's
office for 1 to 2 hours until the sedative wears off. The physician will
make sure you do not have signs of complications before you leave. If
any kind of treatment is done during ERCP, such as removing a gallstone,
you may need to stay in the hospital overnight.
Preparation
Your stomach and duodenum must be empty for the procedure to be accurate
and safe. You will not be able to eat or drink anything after midnight
the night before the procedure, or for 6 to 8 hours beforehand, depending
on the time of your procedure. Also, the physician will need to know whether
you have any allergies, especially to iodine, which is in the dye. You
must also arrange for someone to take you home--you will not be allowed
to drive because of the sedatives. The physician may give you other special
instructions.
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Breath Tests
The lactose breath test and breath hydrogen test are used to evaluate
an individual's ability to digest lactose (sugar from milk products).
The urea breath test is designed to detect
the presence of Helicobacter pylori bacterium.
Lactose
and hydrogen breath Tests
The lactose tolerance test begins with the individual fasting (not eating)
before the test and then drinking a liquid that contains lactose. Several
blood samples are taken over a 2-hour period to measure the person's blood
glucose (blood sugar) level, which indicates how well the body is able
to digest lactose.
Normally,
when lactose reaches the digestive system, the lactase enzyme breaks down
lactase into glucose and galactose. The liver then changes the galactose
into glucose, which enters the bloodstream and raises the person's blood
glucose level. If lactose is incompletely broken down the blood glucose
level does not rise, and a diagnosis of lactose intolerance is confirmed.
The hydrogen
breath test measures the amount of hydrogen in the breath. Normally, very
little hydrogen is detectable in the breath. However, undigested lactose
in the colon is fermented by bacteria, and various gases, including hydrogen,
are produced. The hydrogen is absorbed from the intestines, carried through
the bloodstream to the lungs, and exhaled. In the test, the patient drinks
a lactose-loaded beverage, and the breath is analyzed at regular intervals.
Raised levels of hydrogen in the breath indicate improper digestion of
lactose. Certain foods, medications, and cigarettes can affect the test's
accuracy and should be avoided before taking the test. This test is available
for children and adults.
The lactose
tolerance and hydrogen breath tests are not given to infants and very
young children who are suspected of having lactose intolerance. A large
lactose load may be dangerous for very young individuals because they
are more prone to dehydration that can result from diarrhea caused by
the lactose. If a baby or young child is experiencing symptoms of lactose
intolerance, many pediatricians simply recommend changing from cow's milk
to soy formula and waiting for symptoms to abate.
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Urea Breath Test
The Urea breath test tests for the presence of Helicobacter
pylori bacterium. Urea Breath tests measure carbon dioxide in
exhaled breath. Patients are given a substance called urea with carbon
to drink. Bacteria break down this urea and the carbon is absorbed into
the blood stream and lungs and exhaled in the breath. Analysing the levels
of carbon in the collected breath determine whether H. pylori bacteria
are present or absent. Urea breath tests are 90-99% accurate for diagnosing
the bacteria and are particularly suitable to follow-up treatment to see
if bacteria have been eradicated.
Fasting (usually
4-8 hours) before this test is required. Patients will give a baseline
breath sample by breathing through a small straw into a test tube for
approximately 10 seconds. The patient then drinks a small amount of the
urea and will provide another breath sample 30 minutes later.
Taking antibiotics
or anti-ulcer medication in the two weeks before this test can interfere
with the accuracy of results. Patient should wait at least six weeks after
eradicating an H. pylori infection before repeating this test, to ensure
optimum accuracy.
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Berstein test
The Bernstein test (dripping mild acid through a tube placed in the mid-esophagus)
is often performed as part of a complete evaluation. This test attempts
to confirm that symptoms result from acid in the esophagus. Esophageal
manometric studies- pressure measurements of the esophagus- occasionally
help identify critically low pressure in the Lower esophageal sphincter
(valve separating the stomach and esophagus) or abnormalities in esophageal
muscle contraction.
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24-hour
pH monitoring
For patients in whom diagnosis is difficult, doctors measure the acid
levels inside the esophagus through pH testing. Testing pH monitors the
acidity level of the esophagus and is used to assess the episodes of reflux
and type of activity associated with the symptoms.
A 24 -hour pH monitoring test is one of the most accurate methods for
diagnosing GERD. Acid levels are monitored
for 24 hours by passing a small probe through the nose into the esophagus.
If a patient with daily atypical symptoms tests normal in a pH study,
the physician can abandon a GERD diagnosis and seek other causes. Because
the probe measures only acid, which may not be the only digestive substance
relevant to GERD, the pH monitor examination might yield a false negative
result. False negative results can also occur if the esophagus is overly
sensitive to acid even if the total amount of reflux is normal.
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Radioisotope
gastric-emptying scan
You will eat food that contains a radioisotope, a slightly radioactive
substance that will show up on the scan. The dose of radiation from the
radioisotope is small and not dangerous. After eating, you will lie under
a machine that detects the radioisotope and shows an image of the food
in the stomach and how quickly it leaves the stomach. Gastroparesis is
diagnosed if more than half of the food remains in the stomach after 2
hours.
Gastric
manometry
This test measures electrical and muscular activity in the stomach.
The doctor passes a thin tube down the throat into the stomach. The tube
contains a wire that takes measurements of the stomach's electrical and
muscular activity as it digests liquids and solid food. The measurements
show how the stomach is working and whether there is any delay in digestion.
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