An upper endoscopy can detect a wide range of digestive conditions, from acid reflux damage and ulcers to early-stage cancers and autoimmune diseases like celiac. The procedure uses a thin, flexible tube with a camera to visually inspect your esophagus, stomach, and the first section of your small intestine. Beyond just looking, the scope can also collect tissue samples and even treat certain problems on the spot.
Ulcers and Infections
One of the most common reasons for an endoscopy is to investigate stomach or intestinal ulcers. The camera gives a direct view of any open sores in the lining of your stomach or duodenum (the first stretch of your small intestine). If an ulcer is found, the doctor typically takes a small tissue sample, called a biopsy, to test for H. pylori, the bacterial infection responsible for most peptic ulcers. This matters because treating the infection is what actually heals the ulcer and prevents it from coming back.
The procedure can also identify gastritis, a general inflammation of the stomach lining that causes pain, nausea, or bloating. Gastritis looks like redness and swelling through the camera, and biopsies help determine the underlying cause.
GERD and Esophageal Damage
If you’ve had chronic heartburn or acid reflux, an endoscopy reveals how much damage stomach acid has done to your esophagus. This includes inflammation, erosions, and scarring that can narrow the esophagus over time (called strictures). Strictures make swallowing difficult and sometimes need to be stretched open during the same procedure.
Endoscopy is also the primary tool for detecting Barrett’s esophagus, a condition where the cells lining the lower esophagus change after years of acid exposure. Barrett’s matters because it raises the risk of esophageal cancer. The American Gastroenterological Association updated its guidelines on Barrett’s surveillance in 2025, reflecting how central endoscopy remains to monitoring this condition over time. If Barrett’s is found, you’ll likely need repeat endoscopies on a schedule to watch for precancerous changes.
Celiac Disease
Blood tests can suggest celiac disease, but endoscopy with biopsy is what confirms it. The camera is guided into your small intestine, where the doctor looks for damage to the villi, the tiny finger-like projections that absorb nutrients. A tissue sample is taken and examined under a microscope. In celiac disease, the immune reaction to gluten flattens these villi, which explains the malabsorption, fatigue, and digestive symptoms. You need to still be eating gluten at the time of the procedure for the results to be accurate.
Inflammatory Bowel Disease
Endoscopy plays a key role in diagnosing and monitoring Crohn’s disease and ulcerative colitis. Through the camera, doctors look for specific patterns of damage to the intestinal lining: tiny erosions, larger ulcerations over 5 mm, bleeding within the tissue, and changes in the blood vessel patterns along the intestinal wall. Crohn’s disease can affect the upper GI tract, making upper endoscopy relevant, while colonoscopy (a related procedure using the same technology from the other end) is used to evaluate the colon.
These visual findings help determine how active the inflammation is, which directly influences treatment decisions. Repeat endoscopies are common for people with IBD to track whether their treatment is controlling the disease.
Tumors and Cancer
Endoscopy detects both cancerous and noncancerous growths throughout the upper digestive tract. Polyps, which are small tissue growths on the lining of the stomach or intestine, can often be removed during the procedure itself through a technique called endoscopic mucosal resection. This avoids the need for surgery in many cases.
For suspected cancers of the esophagus, stomach, or duodenum, the endoscope allows the doctor to see the tumor directly, assess its size and location, and take biopsies for lab analysis. When a mass is deeper in the digestive wall or located near the pancreas, a specialized version called endoscopic ultrasound can evaluate it more closely and use a fine needle to collect samples from areas the standard camera can’t reach. This is particularly useful for evaluating pancreatic masses and cysts.
Structural Abnormalities
Several physical problems are visible only through direct examination. A hiatal hernia, where part of your stomach pushes up through the diaphragm into your chest cavity, is commonly spotted during endoscopy. Esophageal varices, which are swollen veins in the esophagus typically caused by liver disease, are another finding. These enlarged veins can bleed dangerously, so identifying them early changes how your condition is managed.
Narrowing or blockages anywhere along the upper digestive tract show up clearly on the camera. These strictures can result from chronic acid damage, scarring from previous surgery, or tumor growth.
What the Procedure Can Do Beyond Detection
An endoscopy isn’t purely diagnostic. During the same session, the doctor can often treat what they find. Common interventions include stretching open narrowed areas, removing polyps or precancerous tissue, stopping active bleeding from ulcers or varices, and removing gallstones stuck in the bile duct. For people with chronic pancreatitis, endoscopy can drain fluid collections and treat strictures in the pancreatic duct.
This dual capability is one of the procedure’s biggest advantages. A problem can be identified and addressed in a single visit rather than requiring a separate surgery.
How to Prepare
Preparation is straightforward. You’ll stop eating solid food after midnight the night before. On the day of the procedure, you should have nothing to eat or drink for at least 8 hours beforehand. Medications can usually be taken up to 4 hours before with small sips of water, though your doctor’s office will give you specific instructions based on what you take.
You’ll receive sedation during the procedure, so you won’t feel the scope and likely won’t remember much of it. The whole thing typically takes 15 to 30 minutes. Because of the sedation, you’ll need someone to drive you home afterward, and most people feel back to normal by the next day.