What Is Endoscopy? Why and How Is It Performed?

Endoscopy examines hollow organs inside the body using a long, flexible tube called an endoscope , which has a camera and light at its tip. It usually enters through the mouth or anus and requires no surgical incision. Endoscopy is a minimally invasive method widely used to diagnose disorders of the digestive system (esophagus, stomach, and intestines) and can also provide treatment when needed. It allows doctors to examine the lining of internal organs in detail without surgery, take tissue samples (biopsies), or perform minor procedures.

What Is Endoscopy?

In simple terms, endoscopy is a method of viewing the inside of the body. A thin, flexible endoscope passes through a natural opening, such as the mouth or anus, to directly inspect an organ's walls. A miniature camera at its tip sends images to a screen. This allows the doctor to examine changes in real time, for example along the upper digestive tract from the esophagus through the stomach to the duodenum.

During endoscopy, patients are usually given sedation , a light form of anesthesia. This makes them drowsy or fully anesthetized during the procedure so that they feel no pain or discomfort. Endoscopy plays a major role in modern medicine because it supports both diagnosis and treatment. Special channels in the endoscope allow procedures such as polyp removal, stopping bleeding , or removing foreign objects during the same session when necessary.

Why Is Endoscopy Performed?

The main purpose of endoscopy is to diagnose the condition causing the patient's symptoms and intervene if necessary. Your doctor may recommend diagnostic endoscopy in the following situations:

• Digestive Symptoms: Endoscopy may investigate persistent or unexplained abdominal pain, difficulty swallowing, persistent heartburn/reflux, ongoing nausea or vomiting, chronic diarrhea or constipation .
• Signs of Bleeding: With signs of upper digestive bleeding, such as blood in the stool or coffee-ground vomit, endoscopy identifies the bleeding source and, where possible, stops it during the same procedure.
• Weight Loss and Anemia: Unexplained weight loss, anemia, or appetite loss may prompt endoscopic examination of the digestive organs to look for an underlying disease.
• Suspected Ulcer or Infection: Endoscopy can examine relevant areas to confirm diagnoses such as stomach ulcers, infections including Helicobacter pylori, or inflammatory bowel diseases , such as Crohn's disease and ulcerative colitis.
• Suspected Tumor or Polyp: If imaging or blood tests raise suspicion of a digestive tract tumor, endoscopy allows direct examination of suspicious areas and biopsy. In particular, detecting and removing polyps is crucial for preventing future cancer.

Endoscopy can be used not only for diagnosis but also for treatment . For example:

• With tiny instruments passed through the endoscope, polyps can be cut out and removed,
• If a bleeding site is found, cauterization or clipping can stop the bleeding,
• If the esophagus is narrowed, a balloon or stent can widen it,
• If a stone is present in the bile duct, ERCP can remove it (ERCP is explained below).

Endoscopy is a versatile procedure that allows diagnosis, observation of an existing problem, and treatment in the same session . Your doctor chooses the most suitable type and plans the procedure for your condition.

How Is Endoscopy Performed?

Before endoscopy, the patient is usually taken to a dedicated endoscopy unit. An intravenous sedative helps them relax and prevents recall of the procedure. The patient then lies on their left side. For upper endoscopy through the mouth, a plastic mouthguard is placed between the teeth to allow the endoscope to pass easily and protect the teeth. If necessary, a local anesthetic throat spray suppresses the gag reflex.

During the procedure, the endoscope is advanced slowly while the doctor views the organ's inner surface on a monitor. In gastroscopy, for example, it passes beyond the base of the tongue into the esophagus and can reach the stomach and duodenum. The camera at the endoscope tip provides detailed images of the lining of these organs. Breathing continues normally throughout; the endoscope does not obstruct breathing. The patient may feel fullness in the throat but usually no pain.

During the examination, the doctor may pass thin instruments through the endoscope to take a biopsy (tissue sample), or remove a polyp with a special loop or snare. Small amounts of air may be introduced through the endoscope to gently inflate the stomach or intestine, allowing movement and improving visibility. Once the examination is complete, the endoscope is slowly withdrawn and the procedure ends.

An upper gastrointestinal endoscopy (gastroscopy) usually takes only a few minutes (an average of 5-10 min). Colonoscopy and other lower digestive endoscopies may take longer because of the length of the bowel (an average of 15-30 min). Afterward, the patient is observed until sedation wears off and is usually discharged the same day.

What Types of Endoscopy Are There?

Endoscopy has different names depending on the area examined. Specialized methods have been developed for almost every hollow organ in the body. Digestive system endoscopies are the most common.

The main types of endoscopy and the areas they examine are summarized below:

The table illustrates the wide range of endoscopic applications. Doctors choose the appropriate method according to the type and location of disease. Gastroscopy is used for stomach symptoms, while colonoscopy is requested for problems involving the colon. ERCP may be considered for suspected bile duct disease, and capsule endoscopy when examination of the entire digestive tract is needed.

Which Type of Endoscopy Is Used When?

Not every endoscopy method is suitable for every situation; each has specific indications. The common types and their uses are summarized below:

• Gastroscopy: Used for persistent heartburn, reflux, difficulty swallowing, upper abdominal pain, unexplained vomiting, suspected stomach ulcers, or a family history of stomach cancer. It can identify ulcers, irritation, or masses in the esophagus, stomach, and duodenum, and obtain biopsies when necessary. For example, in a patient over 45 with persistent heartburn, gastroscopy may be recommended to detect stomach cancer or Barrett's esophagus early.

• Colonoscopy: Performed for findings involving the large intestine, including bleeding, changes in bowel habits such as new constipation or diarrhea, visible or hidden blood in the stool, or unexplained iron deficiency anemia. It is also recommended for screening after a certain age even without symptoms. In particular, colonoscopy screening every 5-10 years for everyone over 45-50 plays a major role in detecting early colon cancer. People with a family history of colon cancer or previous polyps may need earlier and more frequent colonoscopy.

• ERCP: When abdominal ultrasound or MRI shows a stone in the bile duct or narrowing of the bile ducts , or when investigating the cause of pancreatic inflammation (pancreatitis) , ERCP is preferred. The papilla opening into the bile ducts is cannulated, contrast is injected, and fluoroscopic images are obtained. Obstructing gallstones can be removed simultaneously with special baskets. ERCP also provides treatments such as stent placement for bile duct and pancreatic head tumors.

• Endoscopic Ultrasound (EUS): EUS is particularly used for masses around the pancreas or bile ducts detected on ultrasound or CT, or suspected tumors deep in the stomach or esophageal wall. It provides information about nearby lymph nodes and tumor depth, with ultrasound-guided biopsy when needed. For example, it can determine whether a bulge seen in the stomach wall on endoscopy originates in deeper wall layers.

• Capsule Endoscopy: Used for small intestinal bleeding unexplained by other endoscopic methods, iron deficiency anemia, or suspected Crohn's disease in the small intestine. The swallowed capsule provides detailed images, particularly of the middle small intestine beyond the reach of endoscopes. It is ideal for finding lesions in areas inaccessible to conventional endoscopy because of intestinal length. For example, if gastroscopy and colonoscopy are normal in a patient being investigated for occult bleeding, capsule endoscopy can reveal a small intestinal polyp or tumor.

These examples highlight the importance of choosing the right endoscopy for the situation. Doctors decide which procedure is needed by considering symptoms, age, risk factors, and other test results. Sometimes several types are needed in succession, such as capsule endoscopy when gastroscopy is normal but suspicion persists.

Preparing for Endoscopy

To obtain the most accurate results and ensure safety, some preparation before the procedure is necessary. This varies somewhat with the type of endoscopy:

• Diet and Fasting: Most endoscopies require an empty stomach. Before upper gastrointestinal endoscopy (gastroscopy), fasting for 6-8 hours is usually sufficient. For bowel endoscopies such as colonoscopy, patients switch to a low-residue, mainly liquid diet 1-2 days beforehand and use special bowel-cleansing medicines to empty the colon completely. This preparation allows a clear view of the colon and detection of even small lesions. Patients are advised not to consume anything, including water, on the morning of the procedure, particularly if receiving general anesthesia.

• Medicines: Patients should inform their doctor about all regularly used medicines. Blood thinners , such as aspirin, clopidogrel, and warfarin, can increase bleeding risk if a biopsy or polyp removal is planned. They may therefore need to be stopped several days beforehand under medical supervision. The doctor will also determine whether medicines for chronic conditions such as diabetes, hypertension, or heart disease should be taken on the morning of endoscopy.

• Companion and Consent: Because sedation will be given, patients are asked to bring a companion . Drowsiness and reduced alertness may persist for several hours afterward, making driving or traveling home alone unsafe. Patients are asked to leave removable items such as dentures, contact lenses, and jewelry when coming to hospital. Before endoscopy, the patient or legal representative receives information and signs a consent form.

• Other Preparations: The doctor may request additional tests beforehand. Risks are reviewed in special situations, particularly in patients with pacemakers, clotting disorders, or severe COPD. Antibiotic prophylaxis may be used when necessary, for example to prevent infection in patients with heart valve disease. Patients who have previously undergone endoscopy or general anesthesia are asked about any complications during that experience.

In summary: Following your doctor's instructions before endoscopy is very important. Inadequate bowel cleansing may require a repeat colonoscopy, while arriving with a full stomach may make safe endoscopy impossible and lead to cancellation. Carefully follow the dietary, medication, and other preparation instructions you are given.

Precautions After Endoscopy

After endoscopy, patients should recover comfortably and recognize signs of possible complications. Precautions after endoscopy can be summarized as follows:

• Rest and a Companion: Sedation may leave you sleepy and groggy after the procedure. This is normal and usually resolves within a few hours. During this time, you rest in the clinic while vital signs are monitored. After discharge, avoid driving or making important decisions that day and rest at home if possible. Having someone accompany you that day is safer.

• Resuming Food and Drink: Local anesthesia may leave the throat numb immediately after endoscopy. Therefore, do not eat or drink anything for approximately 1-2 hours. Then begin with water or similar fluids; if swallowing is normal, move on to light foods. A normal diet can generally resume a few hours after the procedure. Avoiding gas-producing foods in the first meals after colonoscopy may improve comfort because gas cramps can occur.

• Possible Mild Symptoms: After endoscopy, you may experience a mild sore throat, discomfort when swallowing, or abdominal bloating and gas pain . These symptoms are common and usually resolve on their own within a few hours. Sedative medicines may also cause persistent mild dizziness or drowsiness . Drinking plenty of fluids and resting help these effects wear off quickly.

• When to Contact a Doctor: More serious symptoms can occasionally develop after endoscopy. If any of the following occurs, seek medical attention without delay:

  • Severe or persistent abdominal pain or chest pain
  • Severe nausea or vomiting, particularly vomiting blood
  • Stools that are tarry and dark (which may indicate digestive bleeding)
  • Fever and chills (which may indicate infection)
  • Shortness of breath or worsening difficulty swallowing
    These symptoms may indicate rare complications and should not be ignored.

• Returning to Normal Life: If only sedation was given, patients can usually return fully to normal life the next day. Throat irritation resolves within 1-2 days. If a polyp was removed or a biopsy taken, your doctor may advise avoiding heavy lifting or blood thinners for a while, or following a special diet. Following these instructions minimizes complication risk.

After endoscopy, there is a brief period of rest and self-observation. Most patients go home the same day without problems and resume daily life. Your doctor will explain the precautions needed afterward; follow these instructions.

What Are the Risks of Endoscopy?

Endoscopy is generally considered safe. As with any medical procedure, however, it carries some risks, even if their frequency is very low. Endoscopy-related complications can be listed from less to more common as follows:

• Organ Perforation: One of the rarest and most serious complications is a tear in the esophageal, stomach, or intestinal wall during endoscopy. Although very unlikely, it may require emergency surgery. Severe pain, fever, or abdominal rigidity after the procedure should therefore be reported to a doctor immediately. Fortunately, perforation is extremely uncommon in endoscopies performed by experienced physicians (less than one in a thousand).

• Anesthesia/Sedation Reactions: Sedatives or anesthetics can very rarely cause allergic reactions, respiratory depression, abnormal heart rhythms, or other unwanted effects. The anesthesia team therefore continuously monitors vital signs. The risk may be slightly higher in patients with serious heart or lung disease, so endoscopy in these situations must be performed in a fully equipped center.

• Infection: Endoscopes undergo high-level sterilization before each patient. As a result, infection risk is very low. Additional procedures, such as polyp removal or bile duct stenting, slightly increase the risk. Infections are usually minor and treated with antibiotics. Your doctor may also give preventive antibiotics if a higher risk is anticipated.

• Bleeding: Endoscopy performed solely for viewing does not cause bleeding. However, procedures such as taking a biopsy or removing a polyp may cause minor bleeding, which usually stops on its own or is controlled endoscopically. Small amounts of bloody sputum after upper endoscopy or blood in the stool after colonoscopy during the first 24 hours may reflect bleeding from small vessels. Seek medical attention if bleeding increases.

• Mild Side Effects: These are common, expected temporary effects after the procedure rather than true complications. Throat pain or numbness, abdominal bloating and gas , or cramping pain, and sedation-related mild headache and grogginess belong to this group. They usually disappear within a few hours without lasting harm. Most patients feel completely normal the day after endoscopy.

Serious complications of endoscopy are extremely rare, and its benefits usually far outweigh potential risks. An experienced gastroenterologist working under appropriate conditions minimizes risk. If your doctor recommends endoscopy, they will explain its benefits and risks. Do not hesitate to share any concerns.

Endoscopy and Cancer: Does It Have a Role in Early Detection?

One of the most vital uses of endoscopy is early cancer detection and even prevention . It plays an important role in both diagnosis and treatment, particularly for digestive system cancers:

• Opportunity for Early Diagnosis: Digestive cancers, particularly stomach and colon cancer, often cause no early symptoms. Endoscopy can detect even very small tumors before symptoms develop. For example, a millimeter-sized lesion found during gastroscopy for mild stomach symptoms may be early stomach cancer, and an immediate biopsy can establish the diagnosis. Indeed, endoscopy is one of the most effective methods for diagnosing stomach cancer because it detects the smallest visible abnormalities and allows immediate biopsy. Early diagnosis greatly increases treatment opportunities and success rates.

• Detecting Precancerous Lesions: Cancer generally does not appear suddenly; it often begins as a benign lesion such as a polyp that becomes cancerous over time. Endoscopy is a primary method for detecting these precancerous lesions. Removing intestinal polyps found during colonoscopy in particular prevents future colon cancer. Studies show that regular colonoscopy screening substantially reduces deaths from colon cancer because it offers the chance to detect cancer early or even prevent it by finding and removing polyps before they become cancerous.

• Screening Programs: In high-risk populations, endoscopic screening can detect cancers before they become apparent. For example, colon cancer screening with colonoscopy is recommended from age 45-50 and helps reduce the population burden of colon cancer. In countries such as Japan, where stomach cancer is common, periodic gastroscopy screening above a certain age detects cancers early. In Türkiye, doctors may also recommend preventive endoscopy for people with a family history or certain risk factors.

• Biopsy and Pathology: Another role of endoscopy in cancer diagnosis is obtaining a targeted biopsy . A few square millimeters of tissue can be sampled from a suspicious area under direct vision and sent to pathology. This confirms the diagnosis and identifies the cancer type. If an early-stage cancer is found, the possibility of complete endoscopic removal (endoscopic resection) is assessed. Endoscopy is therefore one of the gold-standard methods for confirming a cancer diagnosis.

• Endoscopic Treatments: Some early-stage cancers can be completely treated endoscopically. Endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD), for example, can remove early stomach and intestinal tumors without surgery. Special endoscopic knives and equipment cut out the tumor-bearing tissue as a single piece. In appropriate cases, this is easier for the patient and preserves organ integrity and quality of life.

Conclusion: Endoscopy is an indispensable tool for early cancer detection and prevention . Colonoscopy can stop a polyp from becoming cancerous, while gastroscopy can detect and treat very early stomach cancer. If your doctor recommends endoscopy for suspected cancer or screening, it offers an important opportunity both for early detection and reassurance. Remember that treating an early cancer is much easier and more successful than treating a late-stage cancer.

Frequently Asked Questions

Does endoscopy hurt? Is it difficult?
No. For patients, endoscopy is generally not a painful procedure. Sedation given beforehand makes the patient drowsy or fully asleep, with no memory of the procedure. An anesthetic throat spray reduces discomfort as the endoscope passes. During endoscopy, therefore, patients generally feel no pain. Mild throat irritation or abdominal gas may occur afterward but usually resolves quickly.

How long does endoscopy take?
Duration depends on the procedure and the area examined. Upper endoscopy (gastroscopy) can often be completed in as little as 5 minutes. Colonoscopy generally takes 15-20 minutes because the entire colon is examined. Additional procedures such as polyp removal may extend this to around half an hour. Afterward, the patient rests until sedation wears off before going home. Preparation and recovery therefore involve a few hours in hospital, but the examination itself takes only minutes.

When can I eat after endoscopy?
After the procedure, you are advised not to eat or drink for about 2 hours. Wait until sedation and throat numbness have completely worn off. Then start with fluids such as water, juice, or tea before moving to light foods. Soft foods may be preferable on the first day if your throat is mildly sore after gastroscopy. After colonoscopy, start with light foods that do not produce gas. Normal eating can usually resume a few hours after endoscopy unless your doctor advises otherwise.

Are endoscopy results available immediately? When will I know them?
Your doctor will share the findings seen during endoscopy as soon as the procedure ends . Many diagnoses can be made immediately from the images; for example, the doctor can tell you if an ulcer or polyp was seen. However, if a biopsy was taken, definitive diagnosis requires the pathology laboratory result. Biopsy results are usually available within 1-2 weeks . At a follow-up appointment, you can learn the pathology result and clarify the treatment plan. Visual findings are immediate; results requiring microscopic examination take longer.

Is there a particular age for endoscopy?
Endoscopy can be performed at any age, including childhood, when needed. For screening and routine checks, it is more common in middle-aged and older people . The World Health Organization and many experts recommend starting colonoscopy screening after age 45-50 , whether or not symptoms are present. Türkiye has no routine age threshold for stomach cancer screening, but gastroscopy may be recommended particularly for people over 50 with risk factors. With a family history of gastrointestinal cancer, relevant screening endoscopies should begin earlier. Although age alone is not an indication, screening endoscopy can save lives as people get older.