When a health care professional suspects a patient is suffering from a gastrointestinal (GI) disease or disorder, or if a patient reports unexplained symptoms in their GI tract, technology offers valuable tools. Diagnostic tests and procedures can range from invasive to non-invasive, simple to more complex, and can help health care professionals learn more about the causes, symptoms, and severity of different health conditions.

On this page, we have information on a wide variety of diagnostic tests commonly used for diagnosing GI diseases and disorders. Click the name of the test you are interested in to expand the section.

Upper Gastrointestinal Tract

Why: If your physician suspects that you could have a disease or disorder in the esophagus, they might order a barium swallow. Some symptoms that might prompt this decision include difficulty or pain while swallowing, pain in the throat or esophagus, upper abdominal pain, or unexplained vomiting. If you have symptoms that occur lower than your esophagus, such as vomiting, abdominal pain, diarrhea, or bloody stools, then your physician might request a barium meal.

Preparing: Since this test involves taking X-rays, you will need to change into a hospital gown and remove any metal jewellery on your torso beforehand. Otherwise, these pieces of metal get in the way of a clear X-ray image. Your physician might also ask you to eat a low-fibre diet in the days leading up to your test, and tell you not to eat, drink, smoke, or chew gum after midnight the night before the procedure to ensure that food does not obstruct the imaging.

How: A technician will take X-ray images of your upper digestive tract while you drink a thick, chalky mixture of barium and water. This mixture coats the walls of the digestive tract and appears white on an X-ray, allowing your health care team to look for any abnormalities in the structure of your GI tract. For a barium swallow, they will take photos of your esophagus and upper stomach, whereas in a barium meal, they will follow the barium that you have swallowed as it travels through your esophagus, stomach, and the upper portion of your small intestine. This test allows health care professionals to see the shape of your gastrointestinal tract, and to measure whether the digestive system is moving food through too slowly, too quickly, or just right.

Complications: Constipation following an upper GI series is common, and you could end up with bowel movements that appear chalky and white for a few days. This is completely normal, but you can relieve some of the constipation by drinking plenty of fluids and eating high-fibre foods after the procedure. Although rare, some individuals can have an allergic reaction to the barium mixture.

Why: Gastroscopy involves your physician using a small camera attached to a long tube (endoscope) to see the inside of your upper gastrointestinal tract. This is useful if they suspect any sort of upper GI illness, including Crohn’s disease, GERD, gastric ulcers, hiatus hernia, celiac disease, and some cancers. Symptoms such as persistent nausea, heartburn, and unidentified stomach pain make you a candidate for gastroscopy.

Preparing: During gastroscopy, your physician needs to have a clear view of all the sections of your upper GI tract, and they will likely ask you to avoid consuming any food or liquids for six to eight hours before your procedure. It is important that you follow all preparation instructions carefully, because any food in your stomach or upper small intestine will block the image.

When you arrive for your appointment, your physician will provide you with a mild sedative to make the scope more comfortable. It is highly unlikely that you will require general anesthesia. The most commonly used type of sedative is conscious sedation, which involves combining a benzodiazepine, which induces relaxation, and an opioid, which reduces pain. A health care professional will administer the sedative via injection. It will make you very relaxed and might make you sleep lightly, and you will likely lose most memories of the procedure. The nurse might spray a topical anesthetic lightly into the back of your throat to reduce any pain or discomfort from the insertion of the endoscope. Your health care team will monitor your vitals during the sedation and procedure. Make sure you speak to your physician beforehand to find out if you should stop taking any of your medications in the days leading up to the scope, to avoid adverse interactions.

How: Your physician will insert a long, narrow tube with a tiny light and camera attached through your mouth and then into your esophagus, stomach, and upper portion of your small intestine. This device transmits to a screen for the team to view what the camera picks up. The physician will observe the tissue and structures of your upper GI tract for anything that appears abnormal and can also retrieve any suspicious-looking tissues (biopsy) to examine later under a microscope for signs of disease, such as inflammation or cancer. The procedure will only take about five minutes, but you will need to wait at the clinic or hospital for an additional 30 minutes following the test, to make sure that you are safely eliminating the sedative from your system. You are considered legally impaired for 24 hours after receiving conscious sedation. Arrange to have a responsible, adult family member or friend ready to pick you up after your appointment, because it isn’t safe to drive after the sedation, and you will be too tired and disoriented to take a taxi or public transit on your own.

Complications: Gastroscopies are generally safe, but there are some potential complications. Some individuals could have a poor reaction to the sedative, and tears to your digestive tissue from the scope are possible in very rare situations.

Why:  Health care professionals can use endoscopic retrograde cholangiopancreatography (ERCP) to examine bile and pancreatic ducts in your digestive system to find out if a blockage is present and can remove tissues to examine after the procedure. Reasons that your doctor might perform this test include pancreatitis, gallbladder disease, and tumours of the bile ducts or pancreas.

Preparing: Preparing for an ERCP involves ensuring you are ready for both the endoscopy and X-ray portions of the exam. Starting the night before an ERCP, you will need to abstain from eating or drinking any foods or beverages. You might also need to avoid high-fibre foods in the days leading up to the exam. Make sure you are not wearing any metal jewellery on your torso, as this interferes with the X-ray images.

How: ERCP uses a combination of endoscopy and X-ray to examine bile ducts and pancreatic ducts. Your physician will insert a flexible scoping device (endoscope) into your mouth and through your esophagus, stomach, and small intestine to view your liver, gallbladder, pancreas, and bile ducts. From there, a technician will take X-rays of the area for later inspection. The test will take approximately 30 minutes to an hour, but you will remain at the hospital for one to two hours following the procedure.

Complications: While an ERCP may help to diagnose conditions within the bile duct, if tissue becomes irritated then this can sometimes lead to acute pancreatitis.

Why: Physicians are increasingly using endoscopic ultrasound as an alternative for ERCP, to examine the digestive system for blockages or other physical complications in the esophagus, stomach, pancreas, gallbladder, and liver. Endoscopic ultrasound involves the same benefits of ERCP, such as a good view of the anatomy and the ability to take biopsies, but does not carry the risk of radiation from X-rays.

Preparing: Follow the same instructions for preparing for a gastroscopy. You will need to avoid consuming any foods or liquids for six to eight hours before the procedure. You will receive conscious sedation, which involves combining a benzodiazepine (induces relaxation) and an opioid (reduces pain) administered via injection. You will feel very relaxed and possibly sleepy, and you will lose most memories of the procedure. It is important to come to your appointment with a responsible adult who can make sure you get home safe, as the effects from the sedative won’t wear off completely until up to 24 hours after administration.

How: This procedure is similar to ERCP, in that it uses an endoscope, but instead of taking X-rays, endoscopic ultrasound uses a miniature ultrasound device attached to the endoscope. This allows for a much clearer view of structures in the intestinal tract than ultrasound from outside the body, as the scope can get much closer to the site of interest. The procedure typically takes about 20 minutes, and you will need to wait at the clinic or hospital for an additional 30 minutes for the sedative to begin wearing off.

Complications: Endoscopic ultrasound is a relatively safe diagnostic test. However, there are risks when taking any sedative, so it is important to follow all instructions your physician gives you, and to disclose if you are taking any other medications. In addition, there is a very small risk of tears in the esophagus or stomach tissue.

Why: Health care professionals use pH monitoring to test for signs of stomach acid in the esophagus. It can help to determine severity of symptoms related to the pH balance of your GI system, such as gastroesophageal reflux disease (GERD). This diagnostic test can help establish whether your current acid suppression or antacid therapy is working effectively or needs updating or modification. It you are experiencing chest pain, sore throat, cough, or hoarseness, this can help your physician figure out if it is due to heartburn or other causes.

Preparing: You won’t need to prepare much for this test. Follow any instructions your health care team provides you with but, generally, you will go about your day normally.

How: Your physician will guide a thin, plastic catheter, with a sensor at the end, down your nose and into your throat, and leave it there for the next 24 hours. They will also provide you with an accompanying monitor. You will need to record any symptoms you experience for the next 24 hours as the probe tests internal pH balances. Wireless pH monitoring is also sometimes available, which involves placing a small capsule with a transmitter in the esophagus. You will then record any symptoms, while the capsule transmits results to an externally attached receiver that you carry, and the capsule will eventually pass through your digestive system. At the end of the testing period for a wireless pH test, your physician will retrieve the equipment and your accompanying notes and review them to form a diagnosis.

Complications: You might experience some discomfort from the catheter, but pH monitoring is an otherwise safe procedure. Some individuals are uncomfortable with their appearance during this time, because part of the catheter is visible.

Why: Your physician will order an esophageal manometry to test movement and pressure in your esophagus, and a gastric manometry to test movement and pressure in your stomach. The most common symptoms that will make your physician recommend esophageal manometry are heartburn, difficulty swallowing, and painful swallowing. Gastric manometry is common if your physician suspects you could have gastric-emptying disorders, such as gastroparesis or dumping syndrome.

Preparing: Your health care team will likely request that you avoid certain medications, including prescription acid suppression medications (PPIs, H2RAs) or over-the-counter antacids (Tums®, Maalox®), as well as beta-blockers, calcium channel blockers, and caffeine. You will also need to avoid eating any food for eight hours leading up to the procedure.

How: You will be awake during the esophageal manometry. Your physician will take a long, slender tube and insert this through your nose, then pass it through your esophagus, and into your stomach. The tube picks up vibrations that occur when the muscles in your esophagus or stomach contract and relays this information to a machine that graphs the data. Your physician or a medical technician will ask you to swallow water at various points, which will help them understand what happens in your esophagus when you eat and drink. The process will take approximately 30 to 45 minutes. This test allows your physician to measure your swallowing strength and look for any anomalies in esophageal or stomach function. They can also check whether the lower esophageal sphincter is working properly.

Complications: While inserting the tube usually goes smoothly, in some individuals it can cause coughing or vomiting as the tube irritates the digestive tract. Your throat might also feel a bit sore right after the esophageal manometry. The insertion of the tube shouldn’t be too uncomfortable, because a health care professional will provide a local anesthetic in your nostril.

Lower Gastrointestinal Tract

The following diagnostic tests (except for anorectal manometry) are typically used for the same purposes, and involve similar preparation. Please read this section, then click on the specific diagnostic test for more information.


If you are experiencing any lower digestive symptoms, including diarrhea, constipation, abdominal pain or cramping, or rectal bleeding, the following diagnostic tests are a useful tool for your health care team to find out what is causing them. The majority of these diagnostic tests serve the same purpose: to look for disease in the large intestine. This can include IBD (such as Crohn’s disease and ulcerative colitis), polyps, colorectal cancer, and diverticular disease. Your physician might also use one of these tests to determine a cause of rectal bleeding or to look for any other abnormalities in the intestinal tract, such as inflammation.


You will need to take into account advance preparation for each of the following diagnostic tests and procedures. It is important for your physician to be able to get a clear view of the structures and tissues in the colon, which requires it to be empty. You must avoid food and opaque liquids (beverages you can’t see through, such as milk, many juices, smoothies, etc.) for at least 24 hours before the procedure, and consume a bowel preparation product according to the product’s instructions to clear out any remaining material in your large intestine. Bowel preparations typically involve combining a powdered product with a clear liquid (such as water or apple juice) and drinking it according to the package instructions. The bowel prep will cause you to use the toilet frequently, so don’t plan any outings away from toilets during this time! Talk to your health care team in advance, so you can complete everything required of you to have an effective and accurate procedure.

During a colonoscopy, you will undergo conscious sedation. This is typically a combination of two medications: a benzodiazepine to help you relax and an opioid to decrease pain. Your health care team will administer the medications intravenously. It will cause you to feel very relaxed and possibly sleepy, and you will likely forget the majority of the procedure. Once the medication has begun to take effect, your physician will insert a device called a colonoscope into your rectum. This allows your physician to view the inside of your bowel, sometimes as far as the location where the small and large intestine meet (terminal ileum). This is a common location for the formation of gastrointestinal conditions such as Crohn’s disease. During the test, your physician can painlessly remove samples from the inside of the colon to be tested later, a procedure known as a biopsy. A colonoscopy can last between 20 and 45 minutes, but you can expect to be at the hospital for 2 to 3 hours in order to get set up properly before and monitored after the procedure.

Colonoscopies are generally very safe. However, there is a small risk of tears or bleeding from the device, especially if your physician chooses to biopsy any tissue. In addition, conscious sedation can have risks, so speak to your physician about any concerns you have and be sure to fully disclose any medications or supplements that you take before the procedure.

Also known as a lower GI series or a colon X-ray, a barium enema is a common test. At the hospital or clinic, a health care professional will administer an enema containing barium, a harmless chemical that shows up bright white on X-ray images. A technician will then take a few X-rays of the region and will often require you to change positions a few times during the process. You will need to remove any metal jewellery or clothing with metal zippers or buttons during the procedure, because these interfere with the X-ray images. The images give your physician a clear view of the bowel contours and any abnormalities that could hint at disease, making diagnosis easier. A barium enema takes between 30 to 60 minutes.

The administration of the enema can be unpleasant; you might feel like you need to have a bowel movement, but you will need to remain still. Although quite rare, some individuals have an allergic reaction to the barium preparation.

While colonoscopy involves analyzing the entire length of the colon, the flexible sigmoidoscopy focuses only on the lower-most section of the colon, the sigmoid. During the procedure, your physician will insert a flexible, tube-like device that features a light and a camera called a sigmoidoscope into your colon. As is the case during a colonoscopy, your physician may biopsy any tissues during a sigmoidoscopy for later testing for diseases such as cancer. Unlike a colonoscopy, you will not need to undergo conscious sedation for this procedure. For most cases, this is the preferred procedure, because most signs of disease appear in the parts of the colon that can be reached with a flexible sigmoidoscope. However, a colonoscopy will allow for a better view of the entire bowel region. The procedure typically lasts about 20 minutes.

This is generally a safe procedure. However, there is a very small risk of damage to intestinal tissue from the scope.

A virtual colonoscopy is somewhat similar to a traditional colonoscopy. During the procedure, your physician will insert a thin tube into the rectum, which they will use to fill the bowel with air. Then, a health care technician will perform a computerized tomographic (CT) scan and use the images to construct a 3-dimensional view of the intestine rather than viewing it directly with a standard camera. Your physician can then examine the images to look for any cancers or malignant polyps. Virtual colonoscopy can sometimes be more effective than a standard colonoscopy, because the 3-dimensional images allow your physician to view parts of the intestine that might not be visible using a standard camera. However, it is less effective at detecting smaller polyps and flat polyps than standard colonoscopy. If your physician discovers any polyps or tissue that require biopsy upon examining the images, you will need to return for a standard colonoscopy in order for them to perform the biopsy.

It can be more difficult to access this test depending on your provincial or personal health care plan. Many plans only cover virtual colonoscopy if there is a reason you are unable to get a standard colonoscopy.

This diagnostic test is useful for detecting illness in any part of the digestive tract, as it involves all areas from gum to bum. Your physician might recommend capsule endoscopy if they suspect you have injury or illness in an area of the intestinal tract that they cannot access easily with standard colonoscopies or endoscopies. It involves swallowing a pill with a tiny video camera (or two cameras, one on either end), a light, batteries, and a radio transmitter. While there is a lot of technology inside this capsule, it is still quite small; about the size of large vitamin pill. As the pill travels through your digestive tract, it takes a series of images, and then it wirelessly transmits the information to a data recording device, which you will wear attached to a belt around your waist. Once the capsule passes through your digestive system (it is fully disposable), you will give the data recording device to your health care team so that they can look over the recorded images. If your physician finds any suspicious tissue, they will likely request a follow-up colonoscopy for a better look at the area and to take a biopsy.

This test can be quite cumbersome for your health care team, as the average capsule endoscopy results in 144,000 images for them to sort through. If you have any strictures, scarring, or inflammation in your intestinal tract, it is possible for the capsule to become stuck. While not immediately dangerous, if you have a tight narrowing of the bowel (stricture) you might require surgery to have it removed, in this rare situation.

Why: Unlike many of the other tests mentioned above, your physician does not use anorectal manometry to look at the inside of your colon, but rather to test the health and strength of your gastrointestinal muscles. If you have been experiencing constipation or fecal incontinence, your physician can use anorectal manometry to analyze the strength of your anal sphincter muscles, to determine if this is the cause of your symptoms.

Preparing: Follow any instructions your physician provides you with before the procedure. This will likely include using an enema to empty your bowel shortly before the test. You also need to avoid any medications that modify gut motility for the 24 hours prior to the test but, in most cases, you can continue to eat or drink in the hours leading up to the procedure.

How: A health care professional will insert a small tube with an attached balloon into your rectum. They will then instruct you to exert your bowels, either pushing or squeezing the muscles at certain times, and will also ask you to relay any information about discomfort or bowel fullness that you feel. The inserted balloon measures pressure and will tell the health care technician if your muscles are functioning normally. The procedure takes about 30 minutes and requires no sedation or in-hospital recovery time.

Complications: This is generally a very safe test, but in some cases the balloon or catheter can irritate the rectum tissue, causing bleeding.