Endoscopic Ultrasound
Endoscopic ultrasound (EUS) combines endoscopy and ultrasonography to obtain detailed images of the internal organs of the digestive system or the lungs. It is a diagnostic procedure that can also be used to perform therapeutic interventions.
General Description
Endoscopic ultrasound (EUS) is a procedure that combines endoscopy with ultrasonography. A flexible tube with an ultrasound probe at its tip is introduced into the body, using sound waves to obtain images that are more detailed than those obtained with conventional endoscopy. This diagnostic technique allows tissue sampling for biopsy (with a fine needle inserted through the catheter tip) and, in some cases, enables treatment in the same session (medication administration or fluid aspiration).
This technique is used to assess the lungs, lymph nodes, major blood vessels, esophagus, stomach, intestines, pancreas, gallbladder, bile ducts, and liver.
Endoscopic ultrasound is a minimally invasive procedure, as no incisions are required; the endoscope is introduced through the mouth or rectum.
When is it indicated?
Endoscopic ultrasound is used to diagnose diseases of the lungs or digestive system and to stage cancerous tumors, providing detailed information on their extent and depth.
Pathologies commonly detected with EUS include:
- Rectal cancer
- Pancreatic cancer
- Esophageal cancer
- Stomach cancer
- Lung cancer
- Benign cysts or lesions in the pancreas, gallbladder, bile ducts, or lungs
- Chronic pancreatitis: persistent inflammation of the pancreas that may lead to impaired function, abnormal digestion, and elevated blood glucose levels
- Inflammatory bowel disease: a group of disorders causing chronic intestinal inflammation due to an inappropriate immune response against the body itself
- Crohn’s disease: a type of inflammatory bowel disease that progresses gradually and occurs in flare-ups, often affecting the distal small intestine and proximal colon
- Gallstones or cholelithiasis: crystallization of bile, the liver-secreted fluid that aids fat digestion, forming stones in the gallbladder
- Gastric varices: dilated veins in the stomach lining
- Gastric lymphoma: a rare cancer originating in the lymphoid tissue of the stomach
- Achalasia: difficulty swallowing due to the inability of the esophageal smooth muscle to relax
- Dieulafoy lesion: a rare gastrointestinal hemorrhage caused by erosion of the stomach wall by an abnormally large and tortuous submucosal artery
- Anorectal fistulas
- Anal sphincter abnormalities
- Sarcoidosis: accumulation of immune cells (granulomas) that become inflamed within the lungs or lymph nodes
How is it performed?
The procedure varies depending on the organ being examined:
- Upper digestive tract or lungs: The endoscopic ultrasound probe is introduced through the mouth.
- Lower digestive tract: The probe is introduced via the rectum.
- An intravenous line is established to administer necessary medications.
- General anesthesia is used to ensure the patient feels no discomfort or awareness of the procedure, which may cause anxiety or distress.
- Local anesthesia spray is also applied to the throat to relax the muscles.
- A mouthguard is placed to prevent dental injury.
- The patient lies on their left side.
- Recovery occurs in the post-anesthesia care unit for 1–2 hours.
- Sedation is typically unnecessary, as the procedure is neither painful nor uncomfortable. However, it may be administered for patients experiencing pain or with increased sensitivity.
- The patient lies on their left side.
- Unless anesthesia is used, no post-procedure observation at the medical center is required.
Risks
Endoscopic ultrasound is generally safe and low-risk. However, when tissue samples are taken for biopsy, potential complications include:
- Bleeding
- Infection
- Tissue tearing
- Intestinal perforation
What to expect from an endoscopic ultrasound
EUS is not painful, but accompaniment is recommended, as driving or making important decisions is not advised immediately after the procedure. The procedure duration ranges from 30 to 120 minutes, depending on the area examined and whether treatment or biopsy sampling is required.
Post-procedure, liquids should be reintroduced gradually, as medications used to insert the probe through the throat may cause choking. Once tolerated, soft foods may be resumed.
Mild discomfort such as sore throat or abdominal distension is common but temporary. Medical attention should be sought only if symptoms persist.
It may take several days (3–4 days) to have a bowel movement due to complete intestinal cleansing, after which normal bowel function resumes.
Images obtained during the procedure are analyzed, and results are communicated to the patient in a follow-up consultation scheduled a few days later.
Specialties in which endoscopic ultrasound is requested
Endoscopic ultrasound is performed within the specialties of General and digestive system surgery and Pulmonology.
How to prepare
Preparation varies according to the organ under examination:
Lungs:
- Fasting for 6–12 hours, including liquids
- Discontinuation of anticoagulant medications
Upper digestive tract:
- Fasting for 8 hours, including water
- If medication is essential, it should be taken with minimal water
Lower digestive tract:
- Low-residue diet 2–3 days prior, avoiding vegetables, fruits with skin or seeds, legumes, whole grains or bread, nuts, and other high-fiber foods
- Clear liquid diet the day before, including filtered broths, tea, infusions, water, and non-carbonated beverages; avoid dairy, juices, and alcohol
- Use of a laxative to ensure complete colon cleansing
- Fasting for 8 hours on the day of the procedure
