Most gastroenterologists use this procedure to determine the size, location, and extent of the spread of the pancreatic tumour. With the help of an EUS-FNA, tissue samples can also be obtained for further evaluation. In addition, this procedure may be used to reduce pain that cannot be resolved with pain medication. This is carried out with the assistance of a celiac plexus block, which involves the injection of a pain reliever to numb the celiac nerves. Celiac plexus blocks are sometimes carried out in patients with chronic pancreatitis as well.