Endoscopic ultrasound (EUS)

An endoscopic ultrasound (EUS) can be used to help diagnose different types of cancer. This includes cancer of the lung or cancers of the digestive tract. The digestive tract includes the oesophagus (gullet), stomach, pancreas and small bowel.

An endoscope is a thin, flexible tube. It can be passed down your throat into your gullet and stomach to look at different areas. With an EUS the end of the endoscope has an ultrasound probe attached to it. The probe produces a picture of the organs that are being examined on a screen. An EUS can be used to:

• look closely for any abnormal areas or at a tumour
• measure a tumour or see if it has spread to areas nearby like lymph nodes
• take samples of cells or tissue (called a biopsy) by passing a thin needle along the endoscope. They look at the samples under a microscope to check for cancer cells. 

You will be given instructions from the hospital on how to prepare for an EUS. They will tell what to expect and how long it is likely to take. Before the EUS a doctor or nurse usually gives you an injection to help you to relax. They also spray local anaesthetic onto the back of your throat.

They pass the endoscope down your gullet or into your stomach and small bowel. They can examine different areas. This depends on the type of cancer you are having tests for: For example:

• in lung cancer EUS can be used to take biopsies, through the gullet, of the lymph nodes in the chest
• if a cancer of the oesophagus or of the stomach is suspected EUS may be used to examine the different layers of these organs
• in cancer of the pancreas they may use EUS to measure a tumour and take biopsies by passing the endoscope into the first part of the small bowel (duodenum).