An endoscopic ultrasound (EUS) is where the doctor uses an instrument called an endoscope, which has an ultrasound probe at its tip to examine the wall layers (inside and outside) of the upper gastrointestinal tract . 

The procedure is performed under sedation or anaesthetic administered by a specialist Anaesthetist

It also provides detailed pictures of your ampulla, pancreas, bile ducts and organs in your chest.

The EUS allows a fine needle aspiration (FNA) of tissue to be taken inside or outside the wall of the gut. This needle is passed through the scope, and using the ultrasound as a guide, it is passed into the tissue of concern

The EUS and FNA are safe procedures. Complications are rare and include: 

• Infection: If a fine needle aspirate (FNA) biopsy is performed, less than 1 in 100 people can develop an infection (especially if sample is taken from a cyst). The risk is reduced substantially with the administration of antibiotics. 
• Bleeding occurs in less than 1 in 200 people. This usually will settle spontaneously or can be stopped at the time of the procedure. Rarely people require further intervention, such as a specialised x-ray procedure or surgery.
• Pancreatitis: Less than 1 in 200 people will experience pancreatitis. Pancreatitis is inflammation of the pancreas which causes it to become swollen and painful. Most pancreatitis will settle within 2-3 days and may require a short stay in the hospital for observation. Rarely, it may be more severe requiring a longer hospital stay.
• Perforation: Less than 1 in 1000 people will accidentally get a hole (perforation) to the bowel. If this was to occur, this may be repaired with small clips during the procedure, or rarely require an operation to repair it.