Endoscopic ultrasound (EUS) combines endoscopy and ultrasound to obtain images and information about the digestive tract and the surrounding tissue and organs.
In EUS, a small ultrasound transducer is installed on the tip of the endoscope. By inserting the endoscope into the upper or lower digestive tract, endoscopists can obtain high-quality ultrasound images of the organs inside the body.
The images obtained are frequently more accurate and more detailed than the ones obtained by traditional ultrasound. EUS can also obtain information about the layers of the intestinal wall and adjacent areas, such as lymph nodes and blood vessels.
EUS was originally developed to detect pancreatic tumors in the earliest, most treatable stages. Today, it remains the primary method for evaluating and staging pancreatic cancer and has emerged as a valuable tool for assessing people at high risk for the disease. In the past few years, however, the role of EUS has expanded well beyond its use in diagnostic imaging.
One of the most important and widely used new applications is EUS-guided fine-needle aspiration (EUS-FNA) cytology. EUS-guided biopsies allow minimally invasive sampling of tissue from tumors and lymph nodes not easily accessible by other methods.
EUS-FNA has significantly changed not only the staging and management of gastrointestinal tract tumors, but also the mediastinal staging of lung cancer, replacing invasive procedures such as mediastinoscopy and thoracoscopy.
EUS-guided biopsies have played an integral role in distinguishing premalignant or malignant pancreatic cysts from benign ones. Now, analysis of cyst fluid proteins collected by EUS-FNA, along with cytology and imaging tests, may help determine which cysts require surgical intervention.
More recently, EUS has evolved from an increasingly sophisticated diagnostic tool into a promising therapeutic one. So far, the most widely available and successful intervention has been pancreatic pseudocyst drainage. EUS guidance allows physicians to image and drain cysts without the risks and potential complications of other methods of cyst puncture.
EUS has also been used to drain abscesses in the abdomen, chest and pelvis. Medical professionals increasingly see it as a safe and effective method for placing fiducial markers in patients undergoing radiation therapy for pancreatic cancer. Fiducials are small, metallic seeds typically made with gold coils. Placed inside a tumor, they reduce organ motion errors, allowing for more precise targeting of tumors and minimizing harm to healthy tissue.
Pancreatic cancer and chronic pancreatitis pain can be treated with EUS-guided celiac plexus neurolysis.
A fellowship-trained physician — most commonly a gastroenterologist with advanced interventional endoscopy training credentials — performs EUS, in many cases adding valuable information and/or therapeutic options to the more established endoscopic retrograde cholangio pancreatography technique.
For more information, contact the Digestive Diseases Center of South Texas PLLC at 210-253-3422 or visit www.ddcst.org. Information is also available from GAB Endoscopy Center Ltd., which can be reached at 210-253-3430 or found online at www.gab-endo.com.