Endoscopic Ultrasound (EUS): Breakthrough Diagnostic Solution in Gastroenterology

Endoscopic Ultrasound (EUS) is an advanced medical technique that combines endoscopy and ultrasound to provide an in-depth and detailed view of the digestive system. This method helps doctors detect small or deep-seated lesions that are difficult to access with conventional techniques, especially crucial in the early diagnosis of serious gastrointestinal diseases, thereby significantly improving treatment effectiveness and patients' quality of life [1]. The EUS scope is a soft, thin tube with a camera, light, and a small ultrasound transducer at its tip, allowing detailed and accurate visualization of structures inside and around the digestive tract [1].

1. WHAT IS ENDOSCOPIC ULTRASOUND?

Endoscopic Ultrasound (EUS) is a specialized procedure that combines two imaging diagnostic methods:

• Endoscopy: Uses a soft, thin tube (endoscope) with a camera and light source at its tip to directly visualize the inner lining of the digestive tract, including the esophagus, stomach, duodenum, and rectum [1].
• Ultrasound: Uses high-frequency sound waves from an ultrasound transducer attached to the end of the endoscope to create detailed images of the bowel wall and adjacent organs/structures such as the pancreas, bile ducts, and lymph nodes [1, 2].

This combination allows EUS to provide high-resolution images, helping doctors assess deep-seated or adjacent lesions that are difficult to access with other methods such as conventional ultrasound or CT scans [1, 2].

2. TYPES OF ENDOSCOPIC ULTRASOUND

Depending on the area to be examined, EUS can be performed in the upper or lower gastrointestinal tract:

2.1. Upper GI EUS for upper gastrointestinal tract examination

This technique is used to examine organs of the upper digestive system including the esophagus, stomach, and duodenum. In addition, upper GI EUS also allows assessment of other important adjacent structures such as the pancreas, common bile duct, gallbladder, and mediastinal lymph nodes [1, 2].

2.2. Lower GI EUS for lower gastrointestinal tract examination

Lower GI EUS focuses on examining the terminal parts of the digestive system such as the rectum and sigmoid colon. This technique also helps evaluate nearby structures such as the prostate, bladder, and pelvic lymph nodes [1].

3. FINE NEEDLE ASPIRATION (FNA)

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is an important technique that allows doctors to collect tissue or fluid samples from suspicious lesions for cytological or histological examination [1, 3].

• Procedure: During EUS, when a lesion requiring diagnosis is identified, a fine needle is threaded through the endoscope, under direct ultrasound guidance, to aspirate a sample from that lesion [1, 3].
• Purpose: This technique helps determine the nature of the tumor (benign or malignant), providing accurate information for diagnosis and treatment planning [1]. EUS-FNA is particularly useful in diagnosing pancreatic cancer, esophageal cancer, and lymph node lesions [3, 4].
• Safety: The complication rate of EUS-FNA is considered very low at qualified and experienced facilities [1, 5].

4. DIAGNOSTIC APPLICATIONS OF EUS

EUS plays a broad diagnostic role, particularly effective in evaluating complex diseases of the digestive system and adjacent organs:

• Assisting in cancer staging: EUS is a superior tool for determining tumor size and the extent of cancer spread, especially for esophageal, gastric, small bowel, rectal, and pancreatic cancers [1, 2]. The ability to differentiate layers of the bowel wall and detect adjacent lymph nodes helps accurately stage cancer according to the TNM system, thereby guiding appropriate treatment methods [1, 4]. EUS-FNA is considered the method of choice for histological diagnosis of pancreatic cancer [3].
• Evaluating lesions within the bowel wall: EUS can detect and differentiate submucosal lesions as benign, pre-cancerous, or malignant [1].
• Pancreatic examination: EUS provides high-resolution images, helping to detect small lesions such as pancreatic tumors, cysts, or diagnose chronic pancreatitis that other methods might miss [1, 2].
• Biliary, gallbladder, and liver examination: EUS helps detect common bile duct stones (even small ones), biliary tumors, and other gallbladder abnormalities [1, 2]. EUS has higher sensitivity than transabdominal ultrasound and is comparable to magnetic resonance cholangiopancreatography (MRCP) in detecting common bile duct stones [2].
• Other applications: EUS is also used to find the cause of fecal incontinence or to evaluate lesions in mediastinal and abdominal lymph nodes [1, 2].

5. THERAPEUTIC APPLICATIONS OF EUS

In addition to its diagnostic role, EUS is increasingly used in minimally invasive therapeutic procedures:

• Drainage of pancreatic pseudocysts and abdominal abscesses: EUS can guide the placement of drainage tubes into pancreatic pseudocysts or abdominal abscesses, helping to decompress and remove accumulated fluid [1].
• Celiac Plexus Block/Neurolysis: Under EUS guidance, doctors can inject pain relievers (alcohol or steroids) into the celiac plexus, a network of nerves that controls abdominal pain, to reduce pain for patients with pancreatic cancer or chronic pancreatitis [1, 2].
• Fiducial marker placement: EUS is used to place gold fiducial markers into tumors, accurately locating the tumor for radiation therapy, especially in the treatment of pancreatic cancer [1].
• Biliary drainage (EUS-BD): In cases of biliary obstruction that cannot be resolved by traditional ERCP methods, EUS can guide the creation of biliary drainage through the stomach or duodenum [1, 3].
• Tumor injection: EUS can be used to directly inject chemotherapy or anti-cancer drugs into tumors, increasing local treatment effectiveness and reducing systemic side effects [3].

6. RISKS AND COMPLICATIONS

Diagnostic Endoscopic Ultrasound (EUS) is generally a safe procedure with a very low complication rate. However, like any invasive medical procedure, EUS also carries some potential risks and complications, especially when fine needle aspiration (FNA) or therapeutic interventions are performed [1, 5]:

• Common complications: Acute pancreatitis (especially when intervening in the pancreas), post-procedure pain, minor bleeding.
• Rare but serious complications: Infection (especially when draining cysts or fluid), gastrointestinal perforation (very rare).

Patients need to be fully informed about potential risks and discuss them with their doctor before undergoing the procedure.

7. THE STRENGTH OF UNIVERSITY MEDICAL CENTER HCMC IN EUS TECHNIQUE

University Medical Center HCMC (UMC) has always been one of the leading medical centers in Vietnam, pioneering the application of advanced diagnostic and treatment techniques. With Endoscopic Ultrasound (EUS) technique, UMC is committed to providing high-quality services through:

• Highly experienced team of specialists: Doctors at UMC are highly trained in gastrointestinal endoscopy and endoscopic ultrasound, with many years of experience in performing complex diagnostic and interventional EUS procedures.
• Modern equipment: The hospital invests in the latest generation of EUS systems, with high-resolution imaging, enabling accurate diagnosis and optimal support for interventional procedures.
• Standardized procedures: EUS procedures at UMC strictly adhere to international medical standards, ensuring maximum safety for patients.
• Diverse applications: UMC widely implements various EUS applications, from early diagnosis of gastrointestinal cancer, staging disease, to therapeutic procedures such as cyst drainage, celiac plexus block, bringing comprehensive treatment effectiveness to patients.

8. FREQUENTLY ASKED QUESTIONS (FAQ)

1. How is EUS different from conventional endoscopy? Conventional endoscopy only allows visualization of the inner surface of the digestive tract. EUS combines endoscopy with ultrasound, allowing a deep view into the bowel wall and adjacent organs, providing more detailed images of submucosal or extraluminal lesions [1].
2. Is EUS painful? EUS procedures are usually performed under sedation or anesthesia, helping patients feel comfortable and pain-free throughout. After the procedure, some patients may experience mild throat discomfort [5].
3. What preparation is needed before EUS? Patients need to fast for a certain period (usually 6-8 hours) before the procedure. The doctor may also request to stop certain medications, especially anticoagulants [5].
4. What diseases can EUS detect? EUS can detect and evaluate many conditions such as esophageal, gastric, pancreatic, and rectal cancers; common bile duct stones; pancreatic cysts; chronic pancreatitis; and submucosal lesions [1, 2].
5. When is EUS necessary? EUS is often indicated when accurate diagnosis or staging of suspected diseases is needed after other imaging methods, or when tissue samples are required from deep, hard-to-reach lesions [1, 2, 5].

9. References

[1] Reddy, Y., & Willert, R. P. (2009). Endoscopic ultrasound: what is it and when should it be used?. Clinical medicine (London, England), 9(6), 539–543. https://pmc.ncbi.nlm.nih.gov/articles/PMC4952290/. Accessed: 2025-12-19. [2] Mekky, M. A., & Abbas, W. A. (2014). Endoscopic ultrasound in gastroenterology: From diagnosis to therapeutic implications. World journal of gastroenterology, 20(24), 7801–7807. https://pmc.ncbi.nlm.nih.gov/articles/PMC4069309/. Accessed: 2025-12-19. [3] Aljahdli, E. S. (2018). Diagnostic and Therapeutic Applications of Endoscopic Ultrasound. Saudi journal of medicine and medical sciences, 6(2), 59–60. https://pmc.ncbi.nlm.nih.gov/articles/PMC6196710/. Accessed: 2025-12-19. [4] Hernandez, L. V., & Bhutani, M. S. (2008). Emerging Applications of Endoscopic Ultrasound in Gastrointestinal Cancers. Gastrointestinal cancer research : GCR, *2_(4), 198–202. https://pmc.ncbi.nlm.nih.gov/articles/PMC2632827/. Accessed: 2025-12-19. [5] Rego, R. (2006). Extraintestinal Applications of Endoscopic Ultrasound. Gastroenterology & hepatology, *2_(4), 261–270. https://pmc.ncbi.nlm.nih.gov/articles/PMC5335681/. Accessed: 2025-12-19. [6] Wang, K. X., Ben, Q. W., Jin, Z. D., Du, Y. Q., Zou, D. W., Liao, Z., & Li, Z. S. (2011). Assessment of morbidity and mortality associated with EUS-guided FNA: a systematic review. Gastrointestinal endoscopy, 73(2), 283–290. https://pubmed.ncbi.nlm.nih.gov/21295642/. Accessed: 2025-12-19.

The information provided is for reference purposes only and does not constitute medical advice. Please consult a doctor for detailed consultation.