Endoscopic Evaluation of the
Upper Digestive Tract
Because of the increase in comfort, safety, and
accuracy of endoscopic examination, it has replaced barium studies as the
procedure of choice for evaluating the esophagus, stomach, and small intestine
and colon. Upper endoscopy is very accurate and is considered the “gold
standard” diagnostic test for most luminal upper digestive tract disorders.
Barium contrast fluoroscopic x-ray studies are highly operator dependent and
limited in quality in the best of hands. For example, barium contrast studies
will be able to diagnose fewer than 65% of the causes of upper gastrointestinal
bleeding (and therefore are contraindicated in such situations). Endoscopy can
be performed in an ambulatory setting and anywhere in the hospital, permits the
taking of pathologic specimens, and may be used to perform therapeutic
interventions. Nearly all patients prefer to be sedated or even to be given
monitored airway control heavy sedation, but such comfort measures are not
essential for all patients and are not provided in all countries. The ordering
physician must know when to use barium contrast studies performed by a
radiologist and when to use endoscopy.
It is important for the clinician
ordering endoscopic procedures to understand their special uses and quality
metrics and the advantages and disadvantages of barium studies compared with
endoscopic studies. Although it is technically the more invasive diagnostic
test, endoscopy is perceived as being more comfortable because it is performed
with sedation, and, therefore, it is much preferred by patients. Endoscopy is
also preferred because it is much more accurate and permits the taking of
specimens for cytologic, microbiologic, or pathologic assessment. It is also
used to perform a wide variety of therapeutic procedures. If appropriate, this
invaluable tool can be brought to the bedside of the sickest patients in the
hospital’s intensive care unit for both diagnostic and therapeutic
interventions. In contrast, all radiologic studies require the transportation
of the patient to the specialized x-ray equipment located in the radiology
department of the hospital, except for the simplest of plain x-rays and
ultrasound studies. This section will briefly describe the process of upper
endoscopic procedures and the use of three upper gastrointestinal endoscopic
procedures, endoscopy, endoscopic retrograde cholangiopancreatography (ERCP),
and endoscopic ultrasonography (EUS). The ordering physician must appreciate
when to use these studies and the potential risks and quality metrics to look
for in the results.
Ensuring the patient’s safety is of
the highest priority in endoscopy. One must ask if the procedure is clearly
indicated, whether this is the safest approach to getting the diagnosis or
treatment, and whether this is the optimal time in the course of the patient’s
illness to perform the procedure. Cardiac, pulmonary, and coagulation studies
are not usually indicated, but they may be needed in select patients who have
unusual risks. The endoscopist must be aware of all underlying medical
conditions, all prescribed and over the-counter medications taken, and any
concerns about the coagulation status. If possible, anticoagulants should be
held if intervention is anticipated, but this is not always possible or
prudent. Knowing the status of the patient’s platelet count and coagulation
tests is imperative if one has any reason to suspect they are abnormal,
especially if intervention is planned. If the patient has an active cardiac or
pulmonary condition, including obstructive sleep apnea, the patient must be
assessed, if necessary by a cardiac or pulmonary specialist. Because morbidly
obese patients are particularly at risk, office endoscopy is not recommended
for them, and they may require preprocedure assessment.
Once the procedure has been scheduled,
the patient must be aware of her or his responsibilities. One of the most
common severe complications from upper endoscopic procedures is aspiration
pneumonia. Except in select cases, the procedure is performed without protection
of the airway by intubation. Thus the patient must have taken no food by mouth
for at least 6 hours and no clear liquids for at least 2 hours. Of course,
these standard times for fasting should be longer in patients at high risk for
aspiration, including those with achalasia and gastric emptying disorders.
Special instructions should be given to patients regarding their blood pressure
and diabetic medications. In patients with active bleeding, the blood pressure
and pulse should be made as normal as possible by crystalloid fluid and, if
necessary, blood resuscitation. Before starting the procedure, time should be
taken to ensure that all providers and nurses are aware of the patient’s risk
factors, including allergies, risks of the procedure to be performed, and risks
of any intended interventions.
Endoscopy is generally a very safe
test and can be performed in nearly all patients with ease and no anticipated ill effects within 5 to 15 minutes (or longer if interventions are
performed). It can provide highly
accurate imaging of the entire upper digestive system to the distal duodenum
or, if enteroscopy is performed, well into the
jejunum or ileum. Histologic,
microscopic, or cytologic specimens increase the diagnostic accuracy with
negligible risk. Interventions are commonly performed with endoscopy, including
dilations of the esophagus or duodenum, the placement of stents to treat
resistant strictures or cancers of the esophagus or duodenum, and the placement
of feeding tubes. The key to quality is adequate analysis of all parts of these
organs with photo documentation and the taking of a sufficient number of
biopsies in accord with published guidelines. It has been shown that the errors
of upper endoscopy occur when sufficient time is not taken to examine parts of
structures that are challenging to see clearly or to achieve a thorough
evaluation. This includes examining all of the esophagus; documenting the site
of the squamocolumnar junction; examining in detail the fundus in a retroflex
view; examining the angularis, pylorus, and all parts of the bulb of the duodenum; and reaching at least the third part of the duodenum. The guidelines for
diagnosing specific upper gastrointestinal disorders should be understood by
the ordering physician (see Sections 2 to 4). For example, one should obtain at
least six biopsy specimens through- out the esophagus to rule out eosinophilic
esophagitis, nine specimens of gastric ulcers to rule out malignancy, and six
specimens of the duodenum, including two in the bulb region, to rule out celiac
disease.
ERCP will be discussed at length in
the chapter on biliary disorders. Only very highly skilled endoscopists perform
this procedure, usually after a fourth year of training or many years of
experience. It can often provide therapeutic intervention that avoids major
surgery, including bile duct stone extraction and ductal stenting. Diagnostic ERCP
has rarely been indicated since EUS and MRCP have become available, both of
which can examine the bile duct and ampulla in detail with negligible risk. In
years past, it was common to hear that the duct could not be cannulated, but in
expert hands, this is now a rare occurrence. Because of its potential duration,
this is the one upper endoscopic examination that may require preemptive
planning for intubation and general anesthesia.
EUS is performed by endoscopists who
are trained at length on its uses. The procedure is performed with an endoscope
that has been modified by the placement of one of several transducer types at
the tip of the scope. It has become the procedure of choice to examine nodes
adjacent to abdominal organs and the esophagus; the distal common bile duct;
submucosal lesions and pancreatic lesions; and fluid collections. It is highly
accurate for lesions that may be only millimeters in diameter because the
transducer is placed directly on the lesion.
It also permits the collection of
cytologic specimens by using fine-needle aspirates of the lesions and/or biopsies.
In the setting of cysts or abscesses, EUS can be used diagnostically to collect
intralesional fluid for culture, cytologic, or biochemical assessment or therapeutically to drain the lesion. It can also be used to guide an interventional
procedure such as pancreatic cyst drainage by creating an endoscopic cyst
gastrostomy.
