CT Scan vs. Endoscopy

What Is the Difference Between CT Scan vs. Endoscopy?

CT scan vs. Endoscopy – quick review:

  • CT scans utilize X-rays to form images of organs and tissues inside the body (for example, abdominal organs, brain, chest, lungs, heart) while endoscopy is a procedure that can visualize only the inside surface of the upper gastrointestinal tract.
  • CT scans use radiation (X-rays) to form images while endoscopy uses a flexible instrument equipped with a light and camera to form images and may be used to collect biopsy of upper gastrointestinal tissues and/or polyp removal.
  • CT scans are quick, painless, noninvasive and does not require extensive preparations; in contrast, endoscopy is invasive (the flexible instrument is inserted through the mouth) and usually requires a person to modify their diet for a short time period while following instructions from your doctor.
  • Individuals undergoing endoscopy usually are given an anesthetic or are mildly sedated as the procedure may be painful or uncomfortable to many patients while most patients undergoing a CT do not require sedation.
  • Both procedures are relatively safe; CT does expose you to radiation (at a safe level) and if IV contrast dye is used to enhance CT images, some people may be allergic or have the possibility of kidney damage while endoscopy has the risk of bowel perforation and allergic reaction to anesthesia drugs.
  • Side effects of colonoscopy may include an irregular heartbeat, pulmonary aspiration and/or respiratory depression – if perforation of the gastrointestinal track occurs, infection and/or bleeding can also happen while for CTs, side effects may include allergic reactions to IV dye, damage to the kidneys from the IV dye and leakage of dye at the IV site.
  • CT scans can be done on individuals at almost any age while the majority of endoscopy procedures are done on adults.

What Is a CT Scan?

CT, or CAT scans, are special X-ray tests that produce cross-sectional images of the body using X-rays and a computer. CT scans are also referred to as computerized axial tomography. CT was developed independently by a British engineer named Sir Godfrey Hounsfield and Dr. Alan Cormack. It has become a mainstay for diagnosing medical diseases. For their work, Hounsfield and Cormack were jointly awarded the Nobel Prize in 1979.

CT scanners first began to be installed in 1974. CT scanners have vastly improved patient comfort because a scan can be done quickly. Improvements have led to higher-resolution images, which assist the doctor in making a diagnosis. For example, the CT scan can help doctors to visualize small nodules or tumors, which they cannot see with a plain film X-ray.

CT Scan Facts

  • CT scan images allow the doctor to look at the inside of the body just as one would look at the inside of a loaf of bread by slicing it. This type of special X-ray, in a sense, takes "pictures" of slices of the body so doctors can look right at the area of interest. CT scans are frequently used to evaluate the brain, neck, spine, chest, abdomen, pelvis, and sinuses.
  • CT is a commonly performed procedure. Scanners are found not only in hospital X-ray departments, but also in outpatient offices.
  • CT has revolutionized medicine because it allows doctors to see diseases that, in the past, could often only be found at surgery or at autopsy. CT is noninvasive, safe, and well-tolerated. It provides a highly detailed look at many different parts of the body.
  • If one looks at a standard X-ray image or radiograph (such as a chest X-ray), it appears as if they are looking through the body. CT and MRI are similar to each other, but provide a much different view of the body than an X-ray does. CT and MRI produce cross-sectional images that appear to open the body up, allowing the doctor to look at it from the inside. MRI uses a magnetic field and radio waves to produce images, while CT uses X-rays to produce images. Plain X-rays are an inexpensive, quick test and are accurate at diagnosing things such as pneumonia, arthritis, and fractures. CT and MRI better to evaluate soft tissues such as the brain, liver, and abdominal organs, as well as to visualize subtle abnormalities that may not be apparent on regular X-ray tests.
  • People often have CT scans to further evaluate an abnormality seen on another test such as an X-ray or an ultrasound. They may also have a CT to check for specific symptoms such as pain or dizziness. People with cancer may have a CT to evaluate the spread of disease.
  • A head or brain CT is used to evaluate the various structures of the brain to look for a mass, stroke, area of bleeding, or blood vessel abnormality. It is also sometimes used to look at the skull.
  • A neck CT checks the soft tissues of the neck and is frequently used to study a lump or mass in the neck or to look for enlarged lymph nodes or glands.
  • CT of the chest is frequently used to further study an abnormality on a plain chest X-ray. It is also often used to look for enlarged lymph nodes.
  • Abdominal and pelvic CT looks at the abdominal and pelvic organs (such as the liver, spleen, kidneys, pancreas, and adrenal glands) and the gastrointestinal tract. These studies are often ordered to check for a cause of pain and sometimes to follow up on an abnormality seen on another test such as an ultrasound.
  • A sinus CT exam is used to both diagnose sinus disease and to detect a narrowing or obstruction in the sinus drainage pathway.
  • A spine CT test is most commonly used to detect a herniated disc or narrowing of the spinal canal (spinal stenosis) in people with neck, arm, back, and/or leg pain. It is also used to detect a fracture or break in the spine.


Skin Cancer Symptoms, Types, Images See Slideshow

What Is an Endoscopy Procedure?

With the procedure known as gastrointestinal endoscopy, a doctor is able to see the inside lining of your digestive tract. This examination is performed using an endoscope-a flexible fiberoptic tube with a tiny TV camera at the end. The camera is connected to either an eyepiece for direct viewing or a video screen that displays the images on a color TV. The endoscope not only allows diagnosis of gastrointestinal (GI) disease but treatment as well.

  • Current endoscopes are derived from a primitive system created in 1806-a tiny tube with a mirror and a wax candle. Although crude, this early instrument allowed a first view into a living body.
  • The GI endoscopy procedure may be performed in either an outpatient or inpatient setting. Through the endoscope, a doctor can evaluate several problems, such as ulcers or muscle spasms. These concerns are not always seen on other imaging tests.
  • Endoscopy has several names, depending on which portion of your digestive tract your doctor seeks to inspect; however, this short article will present the most common usage of the term limited to upper GI endoscopy as other procedures are discussed elsewhere (for example, colonoscopy).
    • Upper GI endoscopy (EGD): This procedure enables the examination of the esophagus, stomach and the upper small bowel called duodenum.
    • Colonoscopy: This procedure enables the doctor to see ulcers, inflamed mucous lining of your intestine, abnormal growths and bleeding in your colon, or large bowel.
    • Enteroscopy: Enteroscopy is a recent diagnostic tool that allows a doctor to see your small bowel. The procedure may be used in the following ways:
      • To diagnose and treat hidden GI bleeding
      • To detect the cause for malabsorption
      • To confirm problems of the small bowel seen on an X-ray
      • During surgery, to locate and remove sores with little damage to healthy tissue
  • Doctors do have other diagnostic tests besides GI endoscopy, including echography to study the upper abdomen and a barium enema and other X-ray exams that outline the digestive tract. Doctors can study the stomach juices, stools, and blood to learn about GI functions. But none of these tests offers a direct view of the mucous lining of the digestive tract.

What Are the Risks of a CT Scan vs. a Gastrointestinal Endoscopy?

CT Scan Risks

CT scan is a very low-risk procedure.

  • The patient will be exposed to radiation when undergoing a CT scan. However, it is a safe level.
  • The biggest potential risk is with a contrast (also called dye) injection that is sometimes used in CT scanning. This contrast can help distinguish normal tissues from abnormal tissues. It also helps to help distinguish blood vessels from other structures such as lymph nodes. Like any medication, some people can have a serious allergic reaction to the contrast. The chance of a fatal reaction to the contrast is about 1 in 100,000. Those at increased risk may require special pretreatment and should have the test in a hospital setting. Anyone who has had a prior contrast reaction or severe allergic reaction to other medications, has asthma or emphysema, or has severe heart disease is at increased risk for a contrast reaction and is referred to a hospital X-ray department for the exam. Besides an allergic reaction, the intravenous dye can damage the kidneys, particularly if an individual already has marginal kidney disease. Usually, the patient is advised to drink plenty of fluids to help flush the dye out of their system.
  • Any time an injection is done into a vein, there is a risk of the contrast leaking outside of the vein under the skin. If a large amount of contrast leaks under the skin, in rare cases, this can cause the skin to break down.

Gastrointestinal Endoscopy Risks

  • Upper GI endoscopy (EGD): Although rare, bleeding and puncture of your esophagus or stomach walls are possible during EGD. Other complications include the following:
  • Severe irregular heartbeat
  • Pulmonary aspiration - When material, either particulate (food, foreign body) or fluid (gastric contents, blood, or saliva), enters from your throat into your windpipe
  • Infections and fever that wax and wain
  • Respiratory depression, a decrease in the rate or depth of breathing, in people with severe lung diseases or liver cirrhosis
  • Reaction of the vagus nerve system to the sedatives
  • Local pain
  • Cardiac arrhythmias
  • Bleeding and infection in the bowel, usually after a biopsy or removal of a polyp.
  • Perforation or hole in the bowel wall

Health Solutions From Our Sponsors

UpToDate. Upper endoscopy (Byond the Basics)

Losacco T. Endoscopic diagnosis of GI tract conditions. Academic Lesson. 2000.

Pansky JL. Upper and lower gastrointestinal endoscopy. In: Nyhus LM, et al, eds. Mastery of Surgery. Vol 1. 1997:246-254.

SAGES. Patient Information from Your Surgeon & SAGES: Upper Endoscopy. Society of American Gastrointestinal Endoscopic Surgeons. Accessed 1997.

SAGES. Patient Information from Your Surgeon & SAGES: Colonoscopy. Society of American Gastrointestinal Endoscopic Surgeons. Accessed 1997.

SAGES. Patient Information from Your Surgeon & SAGES: Flexible Sigmoidoscopy. Society of American Gastrointestinal Endoscopic Surgeons. Accessed 1997. Stark, Paul MD. "Principles of computed tomography of the chest." UptoDate. Updated Jun 2, 2015.
"CT Scan - CAT Scan Imaging - What is a CT Scan." Imaginis.com. Accessed Sept 19, 2016.
Levy, Jason MD. "CT Scan." Medline. Updated Oct 22, 2014.