Physician Center
Referral Indications for Endoscopic Ultrasonography (EUS)
Gastrointestinal Wall
Staging of gastrointestinal tract cancer
The goal of preoperative endosonographic staging is to select patients with resectable lesions and spare other patients the morbidity, mortality, and expense of unnecessary surgery. The staging accuracy of endoscopic ultrasonography (EUS) for gastrointestinal tract (esophageal, stomach, rectal) cancer is far superior to CT or MRI. EUS is indicated when tumor resectability is equivocal on CT.
Occasionally, a gastrointestinal wall cancer may be detected at a very early stage when infiltration is superficial and lymphatic spread has not yet occurred. Such “early cancers” may be amenable to endoscopic resection (“mucosectomy”) for cure and thereby spare the patient open surgery with its attendant morbidity and mortality.
Submucosal tumors
EUS is capable of defining the origin of a submucosal lesion relative to the histologic layers of the gastrointestinal tract as well as the extent of its spread. Genuine submucosal tumors can be distinguished from extramural structures that can compress the bowel wall and thereby mimic a submucosal tumor (e.g., spleen, gallbladder, vascular structures, cysts, and tumors). Although EUS cannot provide a histologic diagnosis, the layer of origin and the echogenicity of the lesion are often highly predictive of the diagnosis. Intramural tumors with characteristic sonographic features include stromal cell tumors, lipomas, duplication cysts, and varices.
Mucosa-associated lymphoid tissue (MALT) lymphoma
EUS is indicated to determine the depth of invasion of MALT lymphoma. Eradication of H.pylori is indicated as first-line treatment when MALT is limited to the mucosa or submucosa.
Anal sphincter defects
EUS provides detailed circumferential images of the internal- and external-sphincter. Traumatic and obstetrical ruptures are identified and quantified for surgical repair.
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Pancreas
Staging of pancreatic cancer
CT and MRI are often unable to determine the respectability of pancreatic cancer, making surgical exploration necessary. The superior resolution of EUS enables more accurate staging to identify the patient with unresectable disease who will not benefit from surgery. If criteria for unresectability are met, endosonography-guided fine-needle aspiration (FNA) is performed in the same session to establish a tissue diagnosis as a prerequisite for adjuvant therapy. FNA is also performed to confirm metastatic spread to regional and distant lymph nodes and the peritoneum (malignant ascites).
Detection of small pancreatic neoplasms
EUS has a sensitivity of nearly 100% in detecting small (<2cm) tumors, providing a negative predictive value of >95%. EUS should be considered as a first-line imaging modality for the detection of neuroendocrine tumors (insulinomas, gastrinomas).
Chronic pancreatitis
EUS is able to identify parenchymal and ductal changes of early chronic pancreatitis that are not detected on transabdominal ultrasound or CT. Indications for EUS include:
1. Recurrent pancreatitis
2. Rule out a pancreatic neoplasm (including an intraductal mucinous neoplasm) that can mimic the symptoms and signs of chronic pancreatitis
ERCP should be reserved for therapeutic intervention in the pancreatic duct. MRCP is very useful to define ductal anatomy in patients with dilated ducts on transabdominal ultrasound or CT.
Acute pancreatitis
EUS may detect biliary lithiasis as an etiology for idiopathic pancreatitis
EUS-guided drainage of pseudocysts
Pseudocysts surrounding the stomach or duodenum can be directly accessed for transmural puncture and internal drainage under ultrasound guidance. EUS has increased the number of patients who are candidates for endoscopic drainage, and has made this approach easier and safer.
EUS-guided celiac plexus neurolysis
High spatial resolution and direct transgastric access to the celiac plexus makes EUS an ideal approach to deliver a celiac axis block. Trials comparing CT- and EUS-guided neurolysis have shown EUS to be the preferred approach.
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Biliary Tract
Endoscopic ultrasound is the most sensitive and specific diagnostic imaging procedure for the detection of CBD and gallbladder stones. The superior spacial resolution of endoscopic ultrasonography enables the detection of small (<3 mm) calculi and biliary sludge (microlithiasis), which account for 13.5% of patients with biliary stones. Indications for EUS to evaluate the biliary tract include:
1. Exclude CBD stones prior to laparoscopic cholecystectomy
2. Exclude an extrahepatic component to cholestasis
3. Exclude biliary lithiasis as an etiology of acute pancreatitis
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Posterior Mediastinum
EUS has the highest resolution of any technology for evaluation of the posterior mediastinum and provides an excellent window of access for tissue sampling (FNA) of lymph nodes and masses. EUS is replacing mediastinoscopy as a first-line procedure for staging non-small cell lung cancer (mediastinoscopy retains a role for the evaluation of the anterior mediastinum). Occult metastatic lymph nodes may be detected in 15-30% of patients with lung CA and negative CT scans.
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