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:
- Evaluation of uncertain finding on other tests (i.e. CT scan, transabdominal ultrasound, MRI, PET scan, upper endoscopy or colonoscopy) especially of abnormalities of the chest or lung cavity, pancreas, bile duct, liver, esophagus, stomach, duodenum, and rectum
- Check for gallstones or common bile duct stones
- Determine the cause of pancreatitis
- Evaluation of pancreatic cysts and deciding whether or not surgey is indicated
- Biopsy of lymph nodes close to the esophagus or mid-chest, stomach, duodenum, or rectum
- Biopsy of left adrenal gland, liver, spleen, and pancreas lesions
- Perform celiac nerve block to relieve pain and decrease pain medication requirements in pancreatic cancer and chronic pancreatitis
- Evaluation of anal sphincters in fecal incontinence
- Evaluation of Barrett’s esophagus with high grade dysplasia before treatment
- Diagnosis, staging to determine the best course of treatment, and surveillance for recurrence after treatment for the following cancers:
esophagus (swallowing tube) cancer
stomach (gastric) cancer
bile duct (cholangiocarcinoma) and ampullary cancer
lung cancer lymph node staging
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.
As a non-surgical, minimally invasive alternative for diagnosing gastrointestinal diseases, EUS has several benefits:
- It is a short procedure (30minutes to 1 hour) performed on an outpatient basis with light sedation and anesthesia, reducing risks and speeding recovery.
- It can provide more accurate diagnosis and staging than CT scans, MRI, or PET scans thereby saving patients from unnecessary surgery or chemotherapy and improve treatment outcomes by helping doctors chose the best course of therapy.
- EUS is less costly than exploratory surgery both in time and money.
As with any medical procedure, complications can occur but are very rare. EUS is generally considered a relatively safe procedure. The risks include:
- A mild sore throat for a day or two after EUS generally relieved with cough drops.
- A very rare chance (less than 1%) of infection, bleeding, or tear of the intestinal wall lining requiring surgery.