Overview
EUS combines endoscopy with ultrasound. The probe is placed inside the stomach or duodenum, providing extremely detailed images of nearby organs (pancreas, bile ducts, lymph nodes, deep structures of the esophagus and stomach wall). Fine needle aspiration (FNA) or biopsy (FNB) can sample tissue safely without surgery.
Who needs it
Pancreatic mass or cyst on imaging
Staging of esophageal, gastric, pancreatic, or rectal cancer
Evaluation for choledocholithiasis when MRCP unclear
Sub-mucosal lesions in the GI tract
Drainage of pancreatic pseudocysts
Risks
Bleeding from biopsy site: <1%
Pancreatitis if pancreatic biopsy: 1-2%
Perforation: rare
Sedation reactions: rare
Infection if cyst drainage: rare with antibiotics
Before the procedure
Fasting 6-8 hours.
Stop blood thinners as directed.
Discuss any sedation concerns.
Arrange a driver.
When to See a Doctor
Call your doctor or go to emergency if after the procedure you have severe or worsening abdominal pain, fever, repeated vomiting, heavy bleeding, black stools or fainting.
Why it is done
Pancreatic mass evaluation and biopsy (cancer or cyst), staging GI cancers (esophageal, gastric, rectal, pancreatic), evaluating bile duct stones missed by other tests, assessing pancreatic cysts, draining pancreatic fluid collections, drainage of pseudocysts.
During the procedure
Sedation through IV. You lie on your left side. The endoscope is passed through the mouth into the stomach or duodenum. The doctor uses the ultrasound to image surrounding organs. If a biopsy is needed, a thin needle goes through the channel of the scope and into the target lesion under ultrasound guidance. Takes 30-60 minutes.
After the procedure
Recovery 30-60 minutes. Sore throat for a few hours. Mild abdominal discomfort if biopsy taken. Resume normal diet same day; avoid strenuous activity for 24 hours. Pathology takes 5-10 days.
When you get the results
Verbal findings same day. Cytology/biopsy results 5-10 days.
Alternatives
CT, MRI, and PET can image these areas but with less detail and inability to biopsy. Surgical biopsy is more invasive.
Questions to ask your doctor
• Is biopsy planned during my EUS?
• What's the chance of finding cancer?
• Will I need additional tests after?
Source and review
This guide comes from the Saudi Gastroenterology Association (SGA) patient library, prepared by the SGA Patient Education Panel. Last reviewed: 2026-04-24. It is for education and does not replace your doctor's advice.
Frequently Asked Questions
What is Endoscopic Ultrasound (EUS)?
Why is Endoscopic Ultrasound (EUS) done?
What are the risks of Endoscopic Ultrasound (EUS)?
How do I prepare for Endoscopic Ultrasound (EUS)?
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