Gastroenterologist: What They Do, Conditions They Treat & When to See One

These affect the esophagus, stomach, and intestines. Examples include gastroesophageal reflux disease (GERD), peptic ulcers, gastritis, irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), celiac disease, and diverticular disease. IBS changes bowel habits without causing inflammation or damage to the gut lining. IBD, which includes Crohn's disease and ulcerative colitis, is chronic inflammation with periods of remission and flare-ups. Celiac disease is an immune response to gluten, a protein in wheat, barley, and rye.

Gastroenterologists evaluate abnormal liver tests and common liver diseases, such as fatty liver disease (MASLD), alcohol-associated liver disease, viral hepatitis, and cirrhosis. They also care for gallbladder and bile duct problems. Gallstones can block bile flow and are often found during tests for another problem. Advanced or complex liver disease is often shared with a hepatologist.

The pancreas makes digestive enzymes. Pancreatitis is inflammation of the pancreas. In acute pancreatitis, the most common causes are gallstones and alcohol use. Chronic pancreatitis is long-term inflammation that can affect digestion and blood sugar control. A gastroenterologist finds the cause and guides treatment.

Gastroenterologists help detect and diagnose cancers of the digestive tract, including colorectal, esophageal, and stomach cancer. Colonoscopy can find and remove polyps and is used for colorectal cancer screening, which guidelines recommend starting at age 45. If cancer is found, your gastroenterologist works with surgeons and oncologists on treatment.

Blood tests check for anemia, inflammation, and nutrient problems. Liver tests measure enzymes such as ALT, AST, and ALP, plus bilirubin. The pattern of enzyme rises helps separate liver cell injury from bile flow problems and narrows the possible causes.

Stool samples can show infection, blood, or inflammation. The fecal immunochemical test (FIT) detects human blood in the stool and is used for colorectal cancer screening. A positive FIT is followed by a colonoscopy. Fecal calprotectin helps check for inflammatory bowel disease.

A doctor passes a flexible, lighted tube with a camera through the rectum to view the colon. It helps diagnose inflammatory bowel disease, find polyps, and screen for colorectal cancer. The doctor can take tissue samples (biopsies) during the exam.

In an esophagogastroduodenoscopy (EGD), a flexible scope passes through the mouth to view the esophagus, stomach, and first part of the small intestine. Doctors use it for symptoms such as trouble swallowing, bleeding, or heartburn that does not respond to treatment. It is also used to confirm celiac disease with biopsies and to screen for enlarged esophageal veins (varices) in people with cirrhosis.

Endoscopic retrograde cholangiopancreatography (ERCP) uses a scope and contrast dye to show the bile ducts and pancreatic ducts, under sedation. Doctors use it to find and remove bile duct stones, place stents, and treat narrowed ducts. It carries a small risk of pancreatitis, so doctors use it when treatment is needed.

You swallow a pill-sized camera that takes pictures as it travels through the digestive tract. It is used to view the small intestine, which standard scopes do not reach well. The capsule passes naturally in the stool, usually within a couple of days.

A biopsy takes a small tissue sample for lab study. It can be taken during an endoscopy or, for the liver, with a needle guided by ultrasound. Imaging includes ultrasound, CT, and MRI. Ultrasound is the usual first test for gallstones. Elastography measures liver stiffness to estimate scarring.