In an ultrasound, a piece of equipment called a transducer is used to detect and transmit high frequency sound waves that are emitted from tissues. The sound waves are converted into electrical impulses which are in turn displayed on a monitor as an image of the region of the body being examined. The results of the procedure can then be interpreted by a doctor.
During an endoscopic ultrasound, the transducer is fixed to the end of an endoscope. The endoscope is a long, thin, flexible tube which is fitted with a camera. The endoscope can be inserted into the esophagus or rectum, allowing a doctor to examine the digestive tract.
Combining endoscopy and ultrasound provides a particular advantage over a traditional ultrasound. This is because fixing the transducer to an endoscope means that the transducer can get very close to the regions of the body which the doctor needs to view. The closer the transducer is, the more accurate the images it can generate, so an endoscopic ultrasound can provide more accurate and more highly detailed images than a conventional ultrasound.
Endoscopic ultrasound can be used for staging cancers (such as pancreatic, esophageal, gastric, and rectal cancer), studying tumors in the liver and gallbladder, studying esophageal and rectal muscles, examining the wall of the digestive tract, and evaluating conditions such as chronic pancreatitis. The procedure can also be combined with a fine needle aspiration for biopsy purposes. The fine needle aspiration can take samples of tissue and fluid from organs, muscle, and the digestive tract.
