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Colonoscopy
EGD
ERCP
Esophageal Dilatation
Esophageal Manometry
Esophageal pH
Liver Biopsy
Flexible Sigmoidoscopy
| | Esophageal pH
 The
esophagus is the muscular tube that carries food and liquid from the throat to
the stomach. However, it is not a rigid tube. The muscles in the wall of the
esophagus automatically contract when a person swallows. This type of
contraction, called peristalsis, occurs as a sweeping wave down the esophagus.
It literally squeezes the food or liquid along from the mouth to the stomach.
Another important part of the esophagus is the Lower Esophageal Sphincter
(LES). It is a strong muscular ring located where the esophagus enters the
stomach. This specialized muscle remains tightly closed most of the time. It is
supposed to open only to allow food and liquid to enter the stomach.
Occasionally the LES opens at the wrong time, allowing caustic stomach acid and
bile to splash up into the esophagus. This is called acid reflux. It is reflux
that is responsible for the discomfort of heartburn. Almost everyone has
experienced heartburn occasionally, and it is nothing to be concerned about.
However, when it happens on a regular basis, it can lead to damage and scarring
in the esophagus.
pH is a measure of acidity or alkalinity. Most people are familiar with pH
tests done on soil or swimming pools. An esophageal pH test measures how often
stomach acid flows into the lower esophagus and the degree of acidity during a
12-24 hour period.
 Equipment
The equipment for esophageal pH consists of a small, thin probe at the end of
tubing. This probe measures acidity. The tubing is gently inserted through the
nose, down to the end of the esophagus. It is attached to a portable recorder
that is carried at the waist. Over 12 to 24 hours, the acidity in the lower
esophagus is recorded on a paper tape. When the patient experiences reflux or
other symptoms, he/she presses a button on the recorder. This marks the time so
as to see how it relates to the acidity levels measured by the probe. The
recording is then analyzed, and a full report is sent back to the physician.
Reason for the Exam
There are a number of symptoms that originate in the esophagus, including
heartburn, difficulty swallowing food or liquid, and chest pain. A measurement
of esophageal pH is of great importance in evaluating these symptoms and
allowing the physician to treat problems of acid reflux. Additionally,
measurement of pH may be helpful in determining the success of treatment for
acid reflux. So, this exam is often done before and after medical and especially
surgical treatment of acid reflux into the esophagus.
X-ray examination (known as upper GI series or barium swallow), and endoscopy
are other diagnostic tests often used when these symptoms are present in the
esophagus. Endoscopy is a visual examination of the esophagus and stomach with a
thin, lighted, flexible tube.
 Preparation
The preparation for esophageal pH measurement is very simple. The patient should
take no food or liquid for about 8 hours before the exam. In most cases, the
physician will want to study the esophagus in its natural state. In other words,
there should not be any medicine in the body that can affect the function of the
esophagus.
Patients should review all medications they are taking with their physicians,
so they can be advised which they should and should not be taking before the
test. Generally, the following list of drugs may affect how much acid flows into
the esophagus. They usually need to be discontinued at least 48 hours before the
test. However, do not stop taking any medication without consulting the
physician.
 | Caffeine (coffee, tea, cola, chocolate)
| Alcohol
| Reglan (generic: metoclopramide)
| Urecholine (generic: bethanechol)
| Erythromycin (E-Mycin, and others)
| Nitroglycerin (Isordil, and others)
| Calcium channel blockers, (Procardia, Adalat, Calan, Cardizem, and others)
| Beta blockers (Corgard, Inderal, Lopressor, and others)
| Donnatol
| Librax
| Levsin
| Tagamet (generic: cimetidine)
| Zantac (generic: ranitidine)
| Pepcid
| Axid
| Prilosec
| Prevacid |
| | | | | | | | | | | | | | | |
The Procedure
It takes about 10-15 minutes to insert and place the pH probe. While the patient
is seated in a chair or lying on his/her side, a thin soft tubing is gently
passed through the nose, or occasionally the mouth. Upon swallowing, the tip of
the tube enters the esophagus and the medical technician or nurse then quickly
passes it down to the desired level. There is usually some slight gagging at
this point, but it is easily controlled by following instructions. The tubing is
then attached to the waist recorder, and the patient is sent on to his or her
regular daily activities. 
Results
Normally there are several mechanisms that keep acid out of the esophagus. The
first is swallowed saliva which helps neutralize stomach acid. Second are the
sweeping muscle contractions that act to cleanse the lower esophagus of acid
reflux. Third is the protective contraction of the LES. Generally, the
esophageal pH test will show a small amount of acid seeping into the esophagus
at various times during the day and night. This is normal for almost everyone,
and the patient may not even be aware of symptoms. However, if the above
protective actions of the esophagus do not function properly, the test will show
a greater degree and duration of stomach acid in the esophagus.
Benefits and Alternatives
The primary benefit of the exam is that the physician has clear documentation of
the degree and duration of acidity in the esophagus. With this information a
specific treatment program can be outlined, or reassurance can be provided if
the exam is normal.
While there are other examinations used to study the esophagus, such as upper
GI series and endoscopy, nothing really takes the place of esophageal pH
measurement. Esophageal pH is often done in association with a pressure
recording of the esophagus, known as Esophageal Manometry.
Side Effects and Complications
Generally, there are no serious problems associated with the esophageal pH test.
Once the tube is in place, it is usually easily tolerated.
Summary
Esophageal pH is a valuable method of determining the severity of acid reflux
into the esophagus. With this information, the physician can usually develop
effective treatment for most patients who have acid disorders in the lower
esophagus.
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