Esophagoscopy and Endoscopic Ultrasound
The ability of being able to introduce a
flexible instrument with a chargecoupled device safely into the
gastrointestinal tract has revolutionized the practice of gastroenterology.
Endoscopic examination of the esophagus shows extensive detail of the mucosal
lining, some imaging of abnormalities that lead to intramural or extramural
indentation or compression of the lumen, respectively, and esophageal motility
abnormalities as estimated by sphincter tone and esophageal diameter. Mucosal
abnormalities seen are best characterized as inflammatory or neoplastic.
Inflammatory lesions may vary in intensity from mild superficial erythema to
frank ulceration with complete destruction of the mucosa.
This process may
occur distally (e.g., gastroesophageal reflux) or proximally (e.g., lichen
planus). The inflammation may also be well localized and discreet (e.g.,
pillinduced esophagitis), patchy (e.g., candidal esophagitis), or diffuse
(e.g., radiation esophagitis or caustic injury). Inflammation may also be seen
indirectly as an esophageal stricture representing a sequela of uncon trolled
or poorly controlled chronic inflammation. Strictures of the esophagus may
appear as bland, tapered narrowings. A stricture may be short or long,
sometimes involving the entire esophagus. The diameter of the stricture may be
widely patent or pinpoint, depending on the cause, and may occur in any portion
of the esophagus. The most common location is the distal esophagus due to the
common cause of gastroesophageal reflux. The stricture may have normal
appearing overlying mucosa or frank erythema and ulceration, depending on the
activity of the underlying inflammatory process.
Endoscopic ultrasound relies on
standard endoscopic technology but with an ultrasound transducer at the end
of the endoscope. This allows for detailed information on the layers of the
esophageal wall and closely apposed structures to the esophagus.
Echographically, the esophageal wall is characterized by layers of varying
echodensity distinguishing the mucosa, submucosa, and muscularis propria.
Newergeneration echoendoscopes may visually further subdivide these layers.
This information is essential for numerous esophageal diseases, including
assessment of the degree of esophageal wall penetration from a mucosal process
such as neoplasia, identification of a lesion originating in a
layer beneath the mucosa, and visualization of periesophageal lymph nodes and
other adjacent structures, such as the aorta, heart, and lung. Furthermore,
endoscopic ultrasound enhances diagnostic accuracy by allowing for placement of
a fine needle into abnormal tissue beneath the mucosa and transmural aspiration
of tissue for histologic analysis. Therapeutic applications are also possible
by drainage of adjacent cystic structures and abscesses.
