Endoscopic ultrasound
Encyclopedia
Endoscopic ultrasound or echo-endoscopy is a medical procedure in endoscopy
(insertion of a probe into a hollow organ) is combined with ultrasound
to obtain images of the internal organs
in the chest
and abdomen
. It can be used to visualize the wall of these organs, or to look at adjacent structures. Combined with Doppler imaging, nearby blood vessels can also be evaluated.
Endoscopic ultrasonography is most commonly used in the upper digestive tract and in the respiratory system. The procedure is performed by gastroenterologists or pulmonologists who have had extensive advanced training. For the patient, the procedure feels almost identical to the endoscopic procedure without the ultrasound part, unless ultrasound-guided biopsy of deeper structures is performed.
, stomach
and duodenum
during a procedure called esophagogastroduodenoscopy
. Among other uses, it allows for screening for pancreatic cancer
, esophageal cancer
, and gastric cancer as well as benign tumors of the upper gastrointestinal tract. It also allows for characterization and biopsy of any focal lesions found in the upper gastrointestinal tract. This is done by inserting a needle through the stomach lining into the target.
Endoscopic ultrasound is performed with the patient sedated. The endoscope is passed through the mouth and advanced to through the esophagus to the suspicious area. From various positions between the esophagus and duodenum organs within and outside the gastrointestinal tract can be imaged to see if they are abnormal and they can be biopsied by a process called fine needle aspiration. Organs such as the liver, pancreas and adrenal glands are easily biopsied as are any abnormal lymph nodes. In addition the gastrointestinal wall itself can be imaged to see if it is abnormally thick suggesting inflammation or malignancy.
The technique is highly sensitive for detection of Pancreatic Cancer (90-95% sensitivity) particularly in patients who are suspected to have a mass or present with jaundice. Its role in staging patients with pancreatic cancer is limited to local metastases; however, in combination with CT scan which provides information on regional metastases, it provides an excellent imaging modality for diagnosis and staging of pancreatic carcinoma.
Endoscopic ultrasound can also be used in conjunction with endoscopic retrograde cholangio pancreatography (ERCP)
. The ultrasound probe is used to locate gall stones which may have migrated into the common bile duct. This occurrence may cause obstruction of the drain shared by the liver and pancreas which may lead to lower back pain, jaundice and pancreatitis.
and colon
, although these applications are lesser known.
It is used primarily to stage newly diagnosed rectal or anal cancer. EUS guided fine needle aspiration may be used to sample lymph nodes during this procedure. Evaluation of the integrity of the anal sphincters may also be done during lower EUS procedures.
Endoscopy
Endoscopy means looking inside and typically refers to looking inside the body for medical reasons using an endoscope , an instrument used to examine the interior of a hollow organ or cavity of the body. Unlike most other medical imaging devices, endoscopes are inserted directly into the organ...
(insertion of a probe into a hollow organ) is combined with ultrasound
Ultrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
to obtain images of the internal organs
Viscus
In anatomy, a viscus is an internal organ, and viscera is the plural form. The viscera, when removed from a butchered animal, are known collectively as offal...
in the chest
Thorax
The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...
and abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
. It can be used to visualize the wall of these organs, or to look at adjacent structures. Combined with Doppler imaging, nearby blood vessels can also be evaluated.
Endoscopic ultrasonography is most commonly used in the upper digestive tract and in the respiratory system. The procedure is performed by gastroenterologists or pulmonologists who have had extensive advanced training. For the patient, the procedure feels almost identical to the endoscopic procedure without the ultrasound part, unless ultrasound-guided biopsy of deeper structures is performed.
Upper digestive tract
For endoscopic ultrasound of the upper digestive tract, a probe is inserted into the esophagusEsophagus
The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...
, stomach
Stomach
The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...
and duodenum
Duodenum
The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms anterior intestine or proximal intestine may be used instead of duodenum...
during a procedure called esophagogastroduodenoscopy
Esophagogastroduodenoscopy
For other expansions of the initialism "OGD", see the disambiguation page.In medicine , esophagogastroduodenoscopy is a diagnostic endoscopic procedure that visualizes the upper part of the gastrointestinal tract up to the duodenum...
. Among other uses, it allows for screening for pancreatic cancer
Pancreatic cancer
Pancreatic cancer refers to a malignant neoplasm of the pancreas. The most common type of pancreatic cancer, accounting for 95% of these tumors is adenocarcinoma, which arises within the exocrine component of the pancreas. A minority arises from the islet cells and is classified as a...
, esophageal cancer
Esophageal cancer
Esophageal cancer is malignancy of the esophagus. There are various subtypes, primarily squamous cell cancer and adenocarcinoma . Squamous cell cancer arises from the cells that line the upper part of the esophagus...
, and gastric cancer as well as benign tumors of the upper gastrointestinal tract. It also allows for characterization and biopsy of any focal lesions found in the upper gastrointestinal tract. This is done by inserting a needle through the stomach lining into the target.
Endoscopic ultrasound is performed with the patient sedated. The endoscope is passed through the mouth and advanced to through the esophagus to the suspicious area. From various positions between the esophagus and duodenum organs within and outside the gastrointestinal tract can be imaged to see if they are abnormal and they can be biopsied by a process called fine needle aspiration. Organs such as the liver, pancreas and adrenal glands are easily biopsied as are any abnormal lymph nodes. In addition the gastrointestinal wall itself can be imaged to see if it is abnormally thick suggesting inflammation or malignancy.
The technique is highly sensitive for detection of Pancreatic Cancer (90-95% sensitivity) particularly in patients who are suspected to have a mass or present with jaundice. Its role in staging patients with pancreatic cancer is limited to local metastases; however, in combination with CT scan which provides information on regional metastases, it provides an excellent imaging modality for diagnosis and staging of pancreatic carcinoma.
Endoscopic ultrasound can also be used in conjunction with endoscopic retrograde cholangio pancreatography (ERCP)
Endoscopic retrograde cholangiopancreatography
Endoscopic retrograde cholangiopancreatography is a technique that combines the use of endoscopy and fluoroscopy to diagnose and treat certain problems of the biliary or pancreatic ductal systems...
. The ultrasound probe is used to locate gall stones which may have migrated into the common bile duct. This occurrence may cause obstruction of the drain shared by the liver and pancreas which may lead to lower back pain, jaundice and pancreatitis.
Lower digestive tract
Echo-endoscopy can also be used for imaging of the rectumRectum
The rectum is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. The human rectum is about 12 cm long...
and colon
Colon (anatomy)
The colon is the last part of the digestive system in most vertebrates; it extracts water and salt from solid wastes before they are eliminated from the body, and is the site in which flora-aided fermentation of unabsorbed material occurs. Unlike the small intestine, the colon does not play a...
, although these applications are lesser known.
It is used primarily to stage newly diagnosed rectal or anal cancer. EUS guided fine needle aspiration may be used to sample lymph nodes during this procedure. Evaluation of the integrity of the anal sphincters may also be done during lower EUS procedures.