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Endoscopic Ultrasonography (EUS)

What is endoscopic ultrasonography?
Indications
Preparation
At the Endoscopy Suite
Procedure
Possible Complications
After the Procedure

What is endocopic ultrasonography?

The combination of the ultrasound probe and an endoscope has led to the development of EUS scopes, or echoendoscopes. These instruments allow examination of both the lining of the digestive tract with the endoscope and the wall of the tract and its surrounding structures such as the liver, pancreas, bile ducts, and lymph nodes. Many other structures can also be seen. Because of these unique capabilities, EUS can sometimes detect abnormalities or obtain information other imaging tests cannot. EUS procedures can be done via the mouth (Upper EUS) or via the rectum (Rectal or Lower EUS).

It is also possible to study the flow of blood in vessels through a process known as Doppler ultrasound or pass a small needle down the endoscope and direct it, under ultrasonic guidance, into structures within or adjacent to the digestive tract, such as lymph nodes or suspicious masses. In this way, tissue can be aspirated for analysis by a pathologist. This technique is known as fine needle aspiration (FNA).

Indications

EUS procedures can provide a variety of information. They are primarily used to detect suspected cancers or to evaluate how far a previously diagnosed cancer has spread in order to determine the appropriate therapy, which is called staging. EUS is used to stage cancers of the esophagus, stomach, pancreas, and rectum. Spread to adjacent lymph nodes and blood vessels can be determined by the imaging and fine-needle aspiration capabilities of EUS.

EUS is also useful in identifying the nature of "lumps" and "bumps" seen on a previous endoscopic exam. These bumps may represent an adjacent structure compressing the GI tract or represent a mass or fluid collection within the wall of the digestive tract. EUS can help differentiate between these possibilities.

EUS also plays a role in evaluating disorders of the pancreas and bile ducts (the tubes that drain bile from your liver and gall bladder). Visualization of the bile ducts is easily accomplished, and the pancreas can be evaluated for the presence of masses, cysts, or changes that suggest chronic inflammation.

Other uses of EUS include evaluating patients with fecal incontinence or stage lung cancers and searching for clots in the vessels of the abdomen using Doppler ultrasound.

Preparation

Bring any x-rays or other relevant tests you have undergone with you. When you arrive at the endoscopy unit, be sure to give your doctor a complete list of all the medicines you are taking and any allergies you have to drugs or other substances. You should specifically mention to your medical team if you are taking any aspirin-containing products, arthritis medicines such as ibuprofen, anticoagulants ("blood thinners"), or diabetic medications, or you have heart, lung, or other medical conditions that may need special attention before, during, or after your procedure.

You will be given instructions in advance that will outline what you should and should not do in preparation for your procedure. Be sure to read and follow these instructions carefully.

One very important aspect of your preparation is not eating or drinking within six hours of the procedure. Food in the stomach will block the view through the endoscope.

At the Endoscopy Suite

Upon arriving, you will change into a hospital gown and remove any glasses, contacts, and dentures you may have. An intravenous needle (IV) will be placed (typically in your arm) into which your sedative medications will be injected when the procedure begins. A detailed medical history will be obtained by the medical staff and you'll be asked to sign a form that verifies your consent to proceed with the test and your understanding of what is involved.

After signing the consent form, you will be taken to the specially equipped procedure room and connected to monitors that will measure your heart rate, your blood pressure, and the oxygenation levels of your blood throughout the procedure. You will be asked to turn onto your left side, and a plastic guard will placed into your mouth to protect your teeth if you are having an Upper EUS. The sedation will then be administered through your IV. Complete anesthesia is rarely necessary. The medications are used to provide relief from discomfort as well as to cause "amnesia", which usually results in your not remembering much, if anything, about the test. At this point, the procedure will begin.

Procedure

During the procedure, we will do everything to help you be as comfortable as possible. Your blood pressure, your pulse, and the oxygen level in your blood will be carefully monitored. As the echoendoscope is slowly and carefully inserted, air will be introduced through it to help your doctor see better. Typically, an EUS procedure lasts between 30 and 90 minutes. Depending on the abnormalities seen, your doctor may choose to collect some tissue samples during the procedure. This can be done with biopsy forceps or via a fine needle aspiration (FNA) procedure. If a fluid collection is seen, it can be suctioned through the scope and sent for analysis. Occasionally, if there is a large cyst in the pancreas that needs drainage, your doctor may place a stent through the stomach or small bowel into the pancreatic cyst.

For patients with pancreatic cancer or severe pain, medications can be injected into the nerves responsible for transmitting this pain. This serves to lessen the pain in these patients for a period of up to several months and is called a celiac-plexus blockade. Based on current evidence, it appears to work better for patients with pancreatic cancer than it does for patients with chronic pancreatitis.

Possible Complications

EUS has been shown to be a safe procedure, similar to other types of endoscopy. The risks are similar to regular endoscopy, except when fine needle aspiration is performed.

First, there is a small risk of having a reaction to the sedative medications or antibiotics that may be given prior to your procedure. This usually results in nausea or a skin rash and usually goes away quickly. Medications to reverse the effects of the sedatives are available, if necessary.

The major risks are perforation (a puncture of the intestinal wall), which could require surgical repair, and bleeding, which could require transfusion. Again, these complications are unlikely. They typically occur from passing the scope through a large tumor or "stretching" or dilating a tumor before or during the EUS procedure.

The risks associated with FNA include bleeding, pancreatitis (rarely, and only if the pancreas undergoes FNA), or infection. In patients undergoing a rectal FNA or an FNA of any cystic lesion, intraprocedural antibiotics are given and followed up with a 5-day course of oral antibiotics after the procedure.

After the Procedure

You will be cared for in a recovery area until most of the effects of the medication have worn off. Typically, this takes 1-2 hours, which is longer than for standard endoscopy. You will likely have to go home with someone else after the procedure. We will give you a prescription for a 5-day course of oral antibiotics if an FNA of a cyst or rectal lesion was performed. You will also be given guidelines for resuming your normal activity before leaving the endoscopy unit.

We will give you a phone number to call, should you experience severe abdominal pain, difficulty swallowing, fever, vomiting up blood, bloody bowel movements, or extreme dizziness/weakness. It is important to contact your physician if you experience any of these effects.