Peninsula Gastroenterology Medical Group, leading GI practice
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Endoscopic Ultrasound (EUS)

What is Endoscopic Ultrasound (EUS)?

Endoscopic ultrasound (EUS) is a state-of-the-art technology that combines endoscopy (link: a low risk diagnostic procedure involving insertion of a flexible tube which transmits images inside the intestinal tract to a TV monitor using computer and fiberoptic technology) and ultrasound (link: ultrasound also called sonography, uses high-frequency sound waves to produce precise images of structures within your body). EUS allows highly detailed examination of each of the 5 layers that line the walls of the intestinal tract. This special capability is very important in determining the depth of esophageal, stomach, rectal, and pancreatic cancer invasion prior to surgery and chemotherapy. EUS is also invaluable for evaluating abnormal “bumps” growing from underneath the first layer of the intestinal wall lining. It also allows visualization and minimally invasive biopsy of internal organs such as the pancreas, bile duct, gallbladder, liver, spleen, lymph nodes, and lesions in the chest cavity. The high resolution of EUS enables detection of small lesions less than 1cm in size such as early cancers, lymph nodes, and bile duct stones that are frequently missed by CT, MRI, and PET scans.

EUS is now considered one of the most essential and cost-effective techniques in the assessment of a wide range of diseases. It is only performed by few specialists in the country and therefore is not widely available. Sequoia is proud to be among the few distinguished centers in the country to offer the innovative technology for advanced patients care.

When is EUS helpful?
EUS is a very sensitive test. It may be helpful in obtaining more information for a diagnosis when other tests are inconclusive. It is also very important in deciding what the best course of treatment should be (e.g.. when and if to start chemotherapy or surgery) in both precancerous and cancer diseases. There are numerous indications for EUS; here are some of the ways EUS can help:

What is cancer staging and why is staging important?
For cancer patients, staging describes the extent of a patient’s cancer, how early or advanced it is. Staging is important because it helps your doctors plan treatment (e.g. surgery or not and if so, should it be performed before or after combination chemotherapy and radiation therapy or no combination therapy at all?). EUS is the most accurate non-invasive way to determine the local extent of many gastrointestinal (GI) cancers (T stage), such as those listed above. In addition, EUS can be used to biopsy many tumors or lymph nodes (N-stage) close to the digestive tract.

What are some alternatives to EUS?
In patients with suspected cancer, biopsies are needed to confirm the diagnosis before any treatment can be started. CT scan or conventional ultrasound-guided biopsies are good methods for tumors close to the skin. However, EUS is safer and more accurate for “deep” tumors, such as those listed above. EUS can obtain biopsies by extracting a small number of cells with a very fine needle from across the digestive tract (esophagus, stomach, intestines and rectum) avoiding damage to overlying vital organs and blood vessels. Surgery for a diagnosis is an alternative to EUS but is much more invasive and requires general anesthesia.

Benefits
As a non-surgical, minimally invasive alternative for diagnosing gastrointestinal diseases, EUS has several benefits:

Risks
As with any medical procedure, complications can occur but are very rare. EUS is generally considered a relatively safe procedure. The risks include:

Additional links:
http://www.asge.org/PatientInfoIndex.aspx?id=380
http://www.cancer.gov
http://www.mayoclinic.org/endoscopic-ultrasound/
http://www.postgradmed.com/issues/2003/04_03/scherer.htm
http://uabhealthtv.photobooks.com/default.asp?ChannelID=4&ProgramID=31