How an endoscopy is performed: step by step, from preparation to recovery

Upon arrival at the endoscopy service, the nursing staff verifies your identity, the medical order, the informed consent, and confirms the fasting. If you have previous exams (previous biopsies, CT, recent blood work), bring them — they help the endoscopist prepare for the procedure.

Before any procedure, the doctor will explain what is going to be done, why, what the risks are (even if minimal), and what alternatives exist. You will sign the informed consent — it is your right to ask anything you need to know before signing it. Do not sign if you have unresolved doubts.

The nurse places a peripheral venous line (catheter in the back of the hand or in the cubital fossa) to administer sedation during the procedure. The pulse oximeter (SpO₂), blood pressure monitor, and ECG if necessary are connected — monitoring continues throughout the entire procedure.

For upper gastrointestinal endoscopy, a local anesthetic spray is applied to the throat (10% lidocaine) to numb the area and reduce the gag reflex. It works in 1–2 minutes. The result is a numbing sensation in the throat — completely normal and temporary.

The doctor or anesthesiologist administers sedation intravenously. The most used drug in Colombia for endoscopy is midazolam + fentanyl (conscious sedation — the patient is relaxed and cooperative but does not remember the procedure) or propofol (deeper sedation — the patient sleeps completely and the anesthesiologist monitors them). The choice depends on the type of procedure, the estimated duration, and the center's preferences. Propofol has an onset of 20–40 seconds and a faster recovery.

For upper gastrointestinal endoscopy, the patient lies on their left side — on the left side. A plastic bite block is placed between the teeth to protect the endoscope and the patient's teeth. The endoscope passes through the bite block — the patient does not need to do anything, they do not bite down hard on the endoscope.

The endoscopist gently introduces the tip of the gastroscope (a flexible tube 8–10 mm in diameter) through the mouth, through the pharynx and esophagus. The greatest discomfort is usually passing through the pharynx — it lasts 2–3 seconds. With sedation, most patients do not notice it. The endoscope has a high-definition camera (HD or 4K depending on the equipment) at its distal end that transmits the image in real time to the room monitor.

With the endoscope inside, the doctor systematically examines the entire esophagus, the cardia and gastroesophageal junction, the gastric fundus (using the retroflexion maneuver — the endoscope makes a curve to see the cardia from below), the gastric body, the antrum, and the pylorus, and finally the first and second portions of the duodenum. A small amount of CO₂ or air is insufflated to distend the stomach and improve visualization — the patient may feel a sensation of fullness or the urge to burp.

If the endoscopist finds a suspicious area — irregular mucosa, ulcer, raised lesion, area with color change, or abnormal vascular pattern — they take one or several biopsies with a biopsy forceps that is introduced through the endoscope's working channel. The tissue is sent to the pathology lab. The biopsy is completely painless — gastric mucosa has no pain receptors. The result arrives in 5–10 business days.

The doctor slowly removes the endoscope while reviewing the mucosa a second time during removal — so as not to miss any detail. The entire procedure lasts between 5 and 20 minutes depending on the findings and additional procedures performed. The patient is transferred to the recovery room.