Once available only in academic centers, endoscopic ultrasound has become an essential tool for any good GI practice.
Endoscopic ultrasound is a procedure in which gastroenterologists use a specialized scope with an ultrasound camera installed at its tip. The procedure was developed in the 1980s, specifically for the detection of pancreatic cancer. Physicians needed to overcome the obstructions of fat, bone, and air, which compromised the image they were able to obtain through transabdominal ultrasound.
The early units—cumbersome, expensive, and difficult to operate—were available only in academic surroundings and a few regional centers. “Doctors weren’t sure as to what the place of EUS would be,” says Dr. Sunil Khurana. “Now, we are at a stage where we can’t do without it. It’s become an essential part of any good GI practice.”
“Using the ultrasound camera, we are able to see deeper layers of intestine, stomach, esophagus and also some structures located immediately outside the GI tract,” explains Dr. Farshad Elmi, one of Premier’s EUS subspecialists (who took a fourth year Advanced Endoscopy Fellowship at Yale University focusing on EUS and ERCP). “The GI tract consists of three layers: the superficial layer or mucosa which can be seen directly during routine endoscopy, the fat layer which is underneath the mucosa, and the muscle layer. EUS allows the endosonographer to examine each of these layers and determine whether there are any pathologic changes in them.”
Putting the technology to work
EUS is a very important tool in local staging of various GI cancers. “The procedure allows for local staging of gastrointestinal tumors to see how deeply the tumor has invaded through the deeper layers of the GI tract, or if it has invaded any surrounding structures outside the GI tract,” says Dr. Elmi. “This helps the surgeon or oncologist to tailor the appropriate surgical and medical treatment.”
Other key indications for employing EUS include:
• To evaluate any submucosal bumps (subepithelial lesions) in the GI tract which are covered with normal appearing mucosa. The endosonographer can also take a deep sample of the lesions using needle aspiration for diagnostic evaluation.
• To visualize the bile duct. EUS provides a very clear picture of the bile duct, revealing the presence of a stone or other obstructive process.
• To obtain tissue biopsy (fine needle aspiration) of any abnormal growth in the pancreas, lymph nodes, or other organs adjacent to the GI tract.
• To evaluate various cystic or solid mass lesions arising from the pancreas. In this regard, EUS can be used for both diagnostic and therapeutic purposes. “If there is a large pancreatic cyst causing mechanical obstruction in the stomach or small bowel, we can go in with EUS to aspirate the cyst and place a small stent to provide ongoing drainage and relieve the obstruction,” says Dr. Elmi.
• Diagnostic EUS is a very safe procedure and the risk of complication is comparable to that of a routine endoscopy. EUS with fine needle aspiration has a small increased risk of complication but it is still a much safer modality than conventional surgical biopsy.