Endoscopic Ultrasonography (EUS)

Endoscopic ultrasonography (EUS) is a medical procedure that combines endoscopy and ultrasound to obtain images of the digestive tract and its surrounding tissues and organs.

How it Works

EUS uses a flexible tube called an endoscope, which is equipped with a high-frequency ultrasound probe at its tip. The endoscope is inserted through the mouth or rectum, depending on the area to be examined, and guided to the desired location. The ultrasound probe emits high-frequency sound waves that bounce off internal structures, creating detailed images of the digestive tract and surrounding tissues.

Indications

EUS is used to evaluate a variety of conditions, including:

• Gastrointestinal cancers (e.g., esophageal, gastric, pancreatic, rectal)
• Inflammatory bowel disease (e.g., Crohn's disease, ulcerative colitis)
• Pancreatic disorders (e.g., pancreatitis, pancreatic cysts)
• Bile duct disorders (e.g., bile duct stones, cholangitis)
• Submucosal lesions (e.g., gastrointestinal stromal tumors, lipomas)

Procedure

The EUS procedure typically takes 30-60 minutes to complete and is performed under conscious sedation or general anesthesia. The patient lies on their back or side, and the endoscope is inserted through the mouth or rectum. The ultrasound probe is then activated, and images are obtained as the endoscope is moved through the digestive tract.

Types of EUS

There are two main types of EUS:

• Radial EUS: uses a rotating ultrasound probe to obtain 360-degree images of the surrounding tissues
• Linear EUS: uses a linear ultrasound probe to obtain images in a single plane, often used for fine-needle aspiration (FNA) or biopsy

Risks and Complications

As with any medical procedure, there are potential risks and complications associated with EUS, including:

• Bleeding or perforation of the digestive tract
• Infection
• Allergic reactions to sedatives or medications
• Respiratory depression

Benefits

EUS offers several benefits, including:

• High-resolution images of the digestive tract and surrounding tissues
• Ability to obtain tissue samples for biopsy or FNA
• Minimally invasive procedure with low risk of complications
• Can be used to guide therapeutic interventions (e.g., tumor ablation, cyst drainage)

Limitations

EUS has several limitations, including:

• Limited depth of penetration (typically 5-10 cm)
• Difficulty visualizing certain areas (e.g., behind the stomach or in the small intestine)
• Operator-dependent technique requiring specialized training and expertise