Endoscopic Ultrasonography (EUS)

What is Endoscopic Ultrasonography (EUS)?

Also called endosonography, this procedure is an important diagnostic and therapeutic method that has become widely used in recent years. Thanks to the ultrasound probe mounted on the tip of the endoscopy device, it allows us to obtain ultrasound images from inside the digestive tract.

It is a method that yields better results in cases where classical ultrasound performed through the abdominal skin cannot provide images (especially due to bowel gas disrupting the image) or where the condition cannot be clearly defined. With this method, we both evaluate the organ from a closer distance and minimize the negative effects caused by bowel gas.

What is Endoscopic Ultrasonography (EUS) used for?

It is a highly effective diagnostic tool especially for evaluating the pancreas, the main bile duct, the area where the pancreatic and bile ducts join and open into the intestine (ampulla),and masses located beneath or adjacent to the digestive tract (in cases where evaluations made with endoscopy do not yield results).

It is an effective method in the diagnosis and follow-up of pancreatic masses and cystic lesions (especially when biopsy is needed). It is more advantageous in detecting small masses or stones in the gallbladder and bile ducts that cannot be seen in imaging methods such as tomography, MRI, or MRCP.

Endoscopic Ultrasonography (EUS) is used in the staging of tumors (esophagus, stomach, and rectum) within its accessible range, in determining whether they have spread to vascular structures, in post-treatment monitoring, and in evaluating whether early-stage tumors originating from the digestive tract can be removed by endoscopic methods without surgery, thereby avoiding unnecessary surgery or endoscopic interventions.

As it is the best method for evaluating the wall layers of the esophagus, stomach, duodenum, and rectum, EUS is effective in visualizing formations located under the inner lining in these areas and findings defined as external compression, and in taking biopsies when necessary. Tumors originating from the muscular layer of the digestive tract wall (such as gastrointestinal stromal tumors, leiomyomas) can be given as examples.

In addition, in recent years, biopsies can also be taken from lymph nodes or masses in the chest cavity adjacent to the esophagus using EUS.

Can a biopsy be taken with Endoscopic Ultrasonography (EUS)? What is it taken for?

EUS not only provides imaging but also allows fine-needle biopsy or fluid sampling from accessible masses and cysts. In cases of advanced pancreatic cancer identified through imaging methods (such as MRI, CT, or PET),a tissue diagnosis required for chemotherapy can be more easily obtained with fine-needle biopsy performed under EUS guidance.

In previous years, diagnosis was attempted using more risky methods, such as CT- or ultrasound-guided external biopsy through the skin. However, the introduction of EUS has made these procedures easier and safer.

What are the interventional procedures performed with Endoscopic Ultrasonography (EUS)?

In addition to its diagnostic use, EUS is also highly effective as a therapeutic method. It is especially useful for draining large cysts and fluid-filled cavities containing necrotic pancreatic tissue that develop after acute pancreatitis—without the need for more risky and complicated surgical procedures. In cases of chronic pancreatitis or advanced-stage pancreatic cancer, EUS-guided nerve blocks are very effective for relieving pain that cannot be controlled with medication.

Are there different types of Endoscopic Ultrasonography (EUS) devices? What are they?

Endoscopic Ultrasonography (EUS) is technically performed using two different types of echoendoscopes. The radial scope provides a 360-degree image, while the linear scope provides an image at an angle of 120–140 degrees. The linear scope is the one used for both diagnostic evaluation and for performing biopsies or interventional procedures. These devices include advanced features such as Doppler, contrast-enhanced, and harmonic imaging capabilities.

How is Endoscopic Ultrasonography (EUS) performed?

The EUS procedure is performed under deep sedation administered by an anesthesiologist, and the patient does not feel any pain or discomfort during the procedure.

Is hospitalization required for Endoscopic Ultrasonography (EUS)?

EUS is mostly performed on an outpatient basis; however, therapeutic interventional procedures generally require hospitalization.

How should one prepare for Endoscopic Ultrasonography (EUS)?

Preparation for the procedure includes fasting for 8 hours and avoiding liquids for 4 hours beforehand. Patients scheduled for a biopsy should consult their relevant specialist to stop taking blood-thinning medications at least 5 days prior to the procedure. If discontinuation is not possible, these medications should be switched to alternatives that do not pose a bleeding risk.