Endoscopic Ultrasound (EUS)
During an endoscopic ultrasound examination a small endoscope (with a small ultrasound probe at the tip) is inserted through the mouth, while the patient is under anestesia. This kind of a scope (echo-endoscope) combines standard endoscopic view and ultrasound images of the gastrointestinal wall and surrounding structures. By this procedure it is possible to examine esophagus, stomach and intestinal wall in detail, exploring any suspicious masses or tumors (including subepithelial lesions). It is the diagnostic method of choice for detailed examination of the structures surrounding the gastrointestinal tract. These include; mediastinum (for lymph nodes or masses), pancreas, biliary structures (including gallbladder), left adrenal gland, parts of liver, vascular structures and lymph nodes of the abdomen. This procedure is typically performed in an outpatient setting, and usually takes between 20 and 45 minutes.
What are the reasons why I need an EUS?
- Esophageal tumors (deciding about tumor depth for treatment planning)
- Esophageal subepithelial tumors (characterization of the lesions below superficial layer but still in the esophageal wall)
- Mediastinal lymph nodes (tumor staging in lung cancer or esophageal cancer)
- Sampling of mediastinal lymph nodes (for tumor staging, or in benign conditions like sarcoidosis,tuberculosis…)
- Stomach tumors (deciding about tumor depth and lymph node status for treatment planning)
- Gastric subepithelial tumors
- Suspected stones in the bile duct
- Dilated bile duct
- Suspected stones in the gallbladder
- Suspected blockage of the bile duct or pancreatic duct
- Biliary tumors
- Pancreatic masses and tumors
- Pancreatic cysts
- Chronic pancreatitis
- Autoimmune pancreatitis
- Acute pancreatitis (in selected cases)
- Dilated pancreatic duct
- Swollen/inflamed pancreas
- History of recurrent episodes of acute pancreatitis
- Anomalies of the pancreas (pancreas divisum, annuler pancreas)
- Duodenal tumors and subepithelial lesions
- Lymph node examination and sampling in the abdomen
- Vascular structures in the abdomen (in selected cases)
Can biopsies be taken at the time of EUS?
One of the advantages of performing an EUS is that biopsies can be obtained at the time of the examination. These biopsies, often referred to as fine-needle aspiration (FNA), can allow for your physician to collect tissue samples which can later be analyzed. Special needles, designed to be used with the EUS scope, allow the physician to insert a small needle through the wall of the esophagus, stomach or intestine directly into the structure or lesion of interest. Because this is done at the time of the EUS, the physician is able to direct the needle to the exact location while watching the needle with the EUS. This is especially important to avoid inadvertant needle pass through vessels or other organs.
FNA is most commonly performed to evaluate masses or lymph nodes. By this highly accurate sampling method it is possible to determine if cancer is present, or what kind of a lesion is present. Another very common reason for performing an FNA is in the evaluation of cysts (especially pancreatic cysts). In these cases, the needle is used to sample the fluid which is contained in the cyst. This fluid can be sent for analysis in order to help characterize the type of the cyst you have.
In certain circumstances, larger biopsy samples may be required. EUS allows the physician to obtain “core biopsies” in a similar fashion to FNA.
What are the advantages of an EUS, compared to a CT or MRI?
There are many different tests which can be used to evaluate a disease process. CT scans and MRI are types of non-invasive tests which allow for detailed imaging of the structures. Drawback of CT scans is to expose the patient to radiation. Furthermore, some patients are unable to receive IV contrast for their CT scans (due to allergies or kidney problems), and thus the quality of the pictures will be not good enough. MRI can be used as an alternative imaging method but, some patients who are claustrophobic may decide against having an MRI performed. EUS allows the physician to get in very close proximity (when compraed with all other methods) to the structures mentioned before (pancreas, biliary tract, gallbladder, mediastinum, intraabdominal lymph nodes) which results in very detailed imaging of the organ or structure of interest. The endoscopist can often times visualize details of the lesion that cannot be seen with either CT or MR. Furthermore, there is no exposure to radiation and no need for contrast to be given. In addition, because the EUS scope has a video camera on it, endoscopic evaluation of the esophagus, stomach, and parts of the small intestine can also be evaluated at the time of the EUS. This is important for some patients who are having a work-up for abdominal pain as it allows for a complete examination of the upper GI system. The biggest advantage of EUS is that, unlike with CT or MR, biopsies can be safely and easily obtained at the time of the examination.
How should I prepare for my EUS?
You should not have anything to eat or drink for approximately 8 hours before your EUS. Typically, patients are asked to refrain from eating or drinking after midnight the night before their test.
Your physician may ask you to hold any anti-agregant or anti-coagulant (blood thinning) medications for 5-7 days before your test depending of your situation or if sampling is needed. You may be allowed to take your other medications on the morning of your test. It is extremely important that you tell your physician what medications you are on (like aspirin, ecopirine, plavix (clopidogrel), eliquis, pradaxa, xarelto, lixiana, coumadine) and discuss if any need to be stopped before the test. If you have a heart disease or severe comorbidity, you may be required to get an opinion from your heart doctor or primary physician responsible for your care stating that it is safe for you to have an EUS & biopsy and receive sedation.