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What are Diagnostic Tests for Gastrointestinal Disorders?

Diagnostic tests for gastrointestinal disorders are laboratory studies or procedures performed to confirm or rule out a disorder of the gastrointestinal system. Before making a treatment plan, your physician needs crucial information for a precise diagnosis, which a diagnostic test can provide.

The gastrointestinal (GI) tract, also known as the alimentary canal or digestive tract, is a pathway or route through which food enters the body and solid wastes are expelled. The GI tract includes the mouth, throat, oesophagus, stomach, small intestine, large intestine, and anus.

Gastrointestinal disorders can range from common digestive problems such as diarrhoea, nausea, and abdominal cramps to chronic disorders including Crohn’s disease, celiac disease, acid reflux, gallstones, irritable bowel syndrome (IBS), colitis, or cancer.

Diagnostic Tests for Gastrointestinal Disorders

In order to arrive at a diagnosis for a gastrointestinal disorder, your physician will usually begin with a review of your symptoms and medical history, followed by a thorough physical examination of the abdomen. To help assess the problem more thoroughly, your physician may recommend additional diagnostic evaluation, such as imaging tests, laboratory tests, endoscopic procedures, and other procedures. These diagnostic tests may include the following:

  • Stool culture: In this test, a patient’s faecal or stool sample is collected and sent for laboratory analysis to look for the presence of abnormal bacteria in the gastrointestinal tract that may cause diarrhoea or other problems.
  • Faecal occult blood test: This is a test to detect the presence of occult or hidden blood in the stool that is not visible to the naked eye. During the test, a very small sample of your stool is taken and placed on a special test card and examined under a microscope. A faecal occult blood test is utilised as an early screening test for colorectal cancer and to diagnose other conditions that may cause bleeding in the GI tract.
  • Magnetic resonance imaging (MRI): This diagnostic procedure utilises a combination of powerful magnets, radiofrequency, and a computer interface to provide detailed images of soft tissue structures and organs in the body, including the digestive system. During the test, you will lie on a bed that moves into a cylindrical cavity, and a series of images is captured. These images are then enhanced by a computer for detailed review.
  • Computed tomography scan (CT or CAT scan): This is a diagnostic test that provides more detailed images of the digestive system than a traditional X-ray. A CAT scan utilises a combination of computer technology and X-rays to produce cross-sectional images of the digestive system and surrounding structures.
  • Ultrasound: Ultrasound imaging is a common diagnostic procedure that uses high-frequency sound waves to produce dynamic images (sonograms) of organs, tissues, or blood flow within the body. It can be used to evaluate the different parts of the digestive system. During ultrasound imaging, a hand-held probe called a transducer is placed directly on the region to be analyzed, and images are projected on a monitor for evaluation by your physician.
  • Lower GI series/barium enema: This is a diagnostic procedure to examine the sections of the lower GI: the lower part of the small intestine, the large intestine, and the rectum. During this test, a fluid called barium (a white liquid that coats the inside of the organs and clearly shows up on an x-ray) is inserted into the rectum via an enema and a series of X-rays are taken. These images help to detect problems such as obstructions (blockages), strictures (narrowed areas), and other issues.
  • Upper GI series and small bowel follow-through series/Barium swallow study: An upper GI series is a diagnostic procedure to inspect the organs of the upper section of the digestive system, namely the oesophagus, stomach, duodenum (the first section of the small intestine), and the small bowel. It involves swallowing a solution containing barium (a water-soluble contrast medium) and capturing a series of images as the barium moves through the digestive system. When only the mouth, throat, and oesophagus are examined, the procedure is called a barium swallow study.
  • Defecography: This is a test in which an X-ray of the anorectal (anus and rectum) area is taken to detect abnormalities, assess rectal muscle contractions and relaxation, and evaluate completeness of stool elimination. During this examination, your rectum is filled with a soft paste that is of similar consistency to stool. You will then be asked to sit on a toilet that has been placed inside an x-ray machine, and squeeze and relax the anus to discharge the paste. Your physician evaluates the x-rays to find out if any anorectal issues occurred while you were expelling the paste from the rectum.
  • Colorectal transit study: This is a diagnostic test to inspect how well food passes through the colon. During this test, you will be asked to swallow capsules containing small markers that can be seen on an X-ray. You will follow a high-fibre diet during the course of the test and the movement of the markers through the large intestine is tracked with a series of abdominal x-rays taken several times 3 to 7 days after taking the capsule.
  • Radioisotope gastric-emptying scan: Prior to this study, you will be asked to consume food containing a radioisotope, a radioactive substance that shows up on a scan. Then you will lie under a CT scan machine for 3 to 5 hours as your radiologist measures the speed at which the food leaves your stomach.
  • Sigmoidoscopy and Proctoscopy: Sigmoidoscopy and proctoscopy are diagnostic procedures performed with lighted viewing tubes called endoscopes introduced through the anus to inspect the lower end of the large intestine (sigmoid colon) and the rectum (just above the anus) respectively. Each procedure uses a particular scope that permits the doctor to inspect for any signs of disease or abnormalities such as tumours, polyps, ulcers, haemorrhoids, inflammation, or bleeding.
  • Colonoscopy: Colonoscopy is an endoscopic procedure used to view the large intestine (colon and rectum) using an instrument called a colonoscope (a flexible tube with a small camera and lens attached at one end). The procedure can detect inflamed tissue, ulcers, and abnormal growths. It is used to diagnose GI disorders such as early colorectal cancer, bowel disorders, abdominal pain, muscle spasms, inflamed tissue, ulcers, and anal bleeding.
  • Anorectal or rectal manometry: This is a test that evaluates how well the anal sphincter and rectum are functioning. It involves inserting a balloon-tipped catheter (a small flexible tube) through the opening of the anus into the rectum, while the other end of the catheter remains outside. The balloon is then gradually inflated, causing the muscles and nerves in the anus and rectum to become squeezed. The catheter is connected to a machine that records the contractions and relaxations of the anal sphincter and rectum.

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