A gastroenterologist checks your stomach using a combination of physical examination, lab tests, imaging, and direct visualization with a tiny camera. The most common and thorough method is an upper endoscopy, where a flexible tube with a camera is guided through your mouth into your stomach. But depending on your symptoms, the process often starts with simpler, less invasive steps before any scope is involved.
The Physical Exam
Your first visit typically begins with a hands-on abdominal exam. The doctor will press on your abdomen using their fingertips, starting with light pressure and moving to deeper palpation. They begin in the area farthest from your pain and work toward it, noting how much pressure it takes to produce tenderness. They’re feeling for masses, guarding (when your muscles tighten involuntarily), and rebound tenderness, which is pain that flares when they release pressure rather than apply it.
Where your pain is located tells them a lot. Pain in the upper middle part of your abdomen (the epigastric area) points toward stomach ulcers, inflammation of the pancreas, or gastrointestinal bleeding. Pain in the right upper area raises suspicion for gallbladder or liver problems. The doctor will also listen to your abdomen with a stethoscope. Overactive bowel sounds can suggest something like diarrhea, while absent sounds over several minutes may indicate a blockage.
Breath and Stool Tests
If your doctor suspects a bacterial infection called H. pylori, which is one of the most common causes of stomach ulcers and chronic inflammation, they can check for it without any invasive procedure at all.
A urea breath test works by having you swallow a pill, liquid, or pudding that contains a specially tagged form of carbon. If the bacteria are present in your stomach, they break down the substance and release the tagged carbon, which you then breathe out. You blow into a collection bag, and a device measures whether elevated levels of that carbon are present. It’s simple, painless, and works for adults and children over six.
Stool tests offer another route. A stool antigen test detects proteins associated with an active H. pylori infection. A more advanced version called a PCR test can not only confirm the infection but also identify whether the bacteria carry genetic changes that make them resistant to certain antibiotics. If you’ve recently taken antibiotics, acid-reducing medications, or bismuth-based products like Pepto-Bismol, your doctor will ask you to wait at least two to four weeks before testing, since these can throw off the results.
Upper Endoscopy: The Most Direct Look
An upper endoscopy (sometimes called an EGD) is the most detailed way to examine your stomach. The endoscope is a long, flexible tube with a small lighted camera at the tip. Your doctor guides it through your mouth, down your esophagus, into your stomach, and into the first part of your small intestine. The whole thing is watched in real time on a video monitor.
During the procedure, air is pumped through the scope to gently inflate your stomach. This smooths out the folds in the lining so the doctor can see the entire surface clearly. If anything looks abnormal, they can pass tiny instruments through a channel in the scope to take tissue samples (biopsies) or even treat small problems on the spot, like cauterizing a bleeding vessel or removing a polyp.
Most people receive a sedative through an IV to stay relaxed and comfortable. You won’t usually be under general anesthesia, but the sedation is enough that many patients don’t remember the procedure afterward. The scope itself typically takes 15 to 20 minutes. Afterward, you’ll rest in a recovery area for about an hour while the sedation wears off. You’ll need someone to drive you home.
Serious complications are rare. Perforation (a tear in the stomach wall) occurs in roughly 1 in 2,500 to 1 in 11,000 procedures. Small tears at the junction of the esophagus and stomach happen in less than 0.5% of diagnostic cases. Overall adverse event rates range from 1 in 200 to 1 in 10,000, with most being minor.
What Biopsies Reveal
When your doctor takes a tissue sample during endoscopy, it goes to a pathologist who examines it under a microscope. They’re looking at several things. First, they check for inflammation and grade it as mild, moderate, or marked based on the types and density of immune cells present. Healthy stomach tissue contains only a handful of immune cells per microscope field, so an increase signals a problem.
The pathologist also looks for signs of long-term damage. Atrophy means the stomach’s normal glandular tissue has been lost. Intestinal metaplasia means stomach cells have started to resemble intestinal cells, which is a change that can increase cancer risk over time. Any abnormal cell growth is graded as low or high grade, which helps your doctor decide how aggressively to monitor or treat it. The report will also note whether H. pylori bacteria are visible in the tissue.
Barium Swallow (Upper GI Series)
Sometimes your doctor orders an imaging study instead of, or before, an endoscopy. An upper GI series uses X-rays combined with a chalky liquid called barium that you drink. The barium coats the lining of your esophagus, stomach, and upper small intestine, making them clearly visible on X-ray in a way they normally wouldn’t be.
You’ll stand or sit in front of an X-ray machine while drinking the barium, then lie on a table while a radiologist watches it move through your digestive tract using real-time X-ray video (fluoroscopy). A technician may press on your abdomen or ask you to shift positions to spread the barium evenly. In a double-contrast version, you also swallow gas-forming crystals that expand your stomach, giving an even sharper view of the lining’s surface detail.
This test can reveal ulcers, hernias, narrowing or scarring of the esophagus or stomach, abnormal growths including cancer, acid reflux, and enlarged veins in the esophagus. It’s painless and doesn’t require sedation, though the barium has a chalky taste and can cause constipation for a day or two afterward.
Gastric Emptying Study
If your main complaint is nausea, bloating, or feeling full after just a few bites, your doctor may suspect your stomach isn’t emptying food properly. A gastric emptying study measures exactly how fast food leaves your stomach.
You’ll eat a standardized meal: scrambled egg whites mixed with a tiny amount of a radioactive tracer, two slices of toast with jam, and a small glass of water. The meal needs to be finished within about 10 minutes. A camera then takes images of your stomach immediately after eating and at one-hour intervals for up to four hours. The images show what percentage of the meal remains in your stomach at each checkpoint. If too much food is still sitting there at the later time points, it confirms delayed gastric emptying.
Capsule Endoscopy
You may have heard of the “pill camera,” a vitamin-sized capsule you swallow that takes thousands of photos as it travels through your digestive tract. It’s most useful for examining the small intestine, which is difficult to reach with a standard scope. For the stomach specifically, it has notable limitations: the capsule can’t be steered, it can’t suction fluid that might block its view, and it can’t take biopsies. A conventional upper endoscopy remains the better tool when the stomach itself is the focus. Still, capsule endoscopy can be a useful noninvasive option when the goal is surveying the broader digestive tract or when a patient can’t tolerate sedation.