What is the purpose of Endoscopic Ultrasound (EUS)?

From the Guidelines

Endoscopic ultrasound (EUS) is a crucial diagnostic tool for evaluating pancreatic cancer, particularly for staging and assessing resectability, with a sensitivity of 90% and specificity of 86% for predicting resectability, as reported in a recent study 1. The procedure involves inserting a thin, flexible tube with an ultrasound probe at its tip through the mouth or rectum to visualize structures such as the esophagus, stomach, intestines, pancreas, liver, and gallbladder. EUS is particularly valuable for:

• Diagnosing and staging gastrointestinal cancers
• Evaluating pancreatic diseases
• Assessing abnormalities in the digestive tract walls
• Examining bile ducts The procedure typically takes 30-90 minutes and is performed under sedation to ensure patient comfort. Patients usually need to fast for 6-8 hours before the procedure. EUS is superior to conventional imaging techniques like CT or MRI for certain conditions because it can detect smaller lesions and provide more detailed images of the digestive tract walls. Additionally, EUS allows for tissue sampling through fine needle aspiration (FNA) or biopsy during the same procedure, enabling immediate collection of cells or tissue for laboratory analysis, with a diagnostic accuracy of up to 95% when carried out by an experienced cytopathologist 1. Potential complications are rare but may include bleeding, infection, or perforation of the digestive tract. According to a recent clinical practice update, EUS is the modality of choice to evaluate indeterminate subepithelial lesions of the GI tract and/or if non-diagnostic tissue by forceps biopsies 1. In the context of pancreatic adenocarcinoma, EUS has been shown to be valuable in detecting vascular invasion and predicting resectability, with a sensitivity of 85% and specificity of 91% for detecting vascular invasion 1. The role of EUS in staging pancreatic cancer is felt to be complementary to pancreas protocol CT, which is considered the gold standard, and EUS provides additional information for patients whose initial scans show no lesion or whose lesions have questionable involvement of lymph nodes outside the resection zone 1. Overall, EUS is a powerful diagnostic tool that can provide valuable information for the diagnosis and staging of pancreatic cancer, and its use should be considered in the diagnostic workup of patients with suspected pancreatic cancer.

From the Research

Overview of Endoscopic Ultrasound

• Endoscopic ultrasound (EUS) is an accurate technique for the diagnosis and staging of benign and malignant lesions in the gastrointestinal tract and the mediastinum 2.
• EUS overcomes the limitations of other imaging diagnostic methods and gives the possibility to obtain tissue for histologic diagnosis (EUS guided FNA) 2.

Diagnostic Applications

• The most useful indications of EUS are differentiation of submucosal tumors, staging for neoplasia, examination of the pancreato-biliary system and therapeutics 2.
• EUS can distinguish extrinsic compressions from intramural lesions and defines their nature (solid, cystic or vascular) and origin 2.
• EUS is useful for local staging of esophageal, gastric, duodenal, and rectal cancer using the TNM (tumor, node, metastases) system, as well as for diagnosing and staging of pancreatic lesions 2, 3, 4.
• EUS is highly sensitive for the diagnosis of choledocholithiasis, avoiding unnecessary danger of diagnostic ERCP 2, 3, 4.

Therapeutic Applications

• New therapeutic indications of EUS include drainage of pancreatic pseudocysts and abscesses and celiac plexus block and neurolysis 2, 3, 4, 5.
• EUS-guided FNA has improved the ability to detect malignant lymph node invasion 2.
• EUS has become an indispensable diagnostic method in gastroenterological everyday practice and should be part of most endoscopy units 2.

Advances in EUS Techniques

• New techniques such as elastography and contrast enhancement have emerged, increasing the accuracy, sensitivity and specificity of EUS for the diagnosis of digestive tract diseases including pancreatic masses and lymphadenopathy 6.
• EUS-elastography evaluates tissue elasticity and therefore, can be used to differentiate various lesions 6.
• Contrast-enhanced EUS can distinguish benign from malignant pancreatic lesions and lymphadenopathy using the intravenous injection of contrast agents 6.