What Is the Purpose and Use of Diagnostic Testing?

The primary purpose of diagnostic testing is to detect a disease, its outlook, and its spread throughout the body.

Diagnostic tests are used widely over the world with the primary purpose of detection of disease, its outlook, and its spread in the body.

Diagnostic testing is used for the following purposes:

1. Identification
   • Once your doctor evaluates your signs and symptoms, takes your medical history, and performs a physical examination, they will want to know the cause of your symptoms—whether they are because of a specific disease or they are a byproduct of your disease process (e.g., a proinflammatory body state is often a byproduct of diabetes).
   • They will want to confirm a suspected condition or exclude other conditions by ordering diagnostic tests. Early detection with the help of diagnostic tests can help your doctor start prompt treatment and halt the progression of the disease. 
   • Even if no particular condition is causing your symptoms, your doctor can suggest following some prevention tips based on your lifestyle and risk factors. 
2. Monitoring
   • After you have been diagnosed with a particular medical condition/disease, your doctor may recommend a wait-and-watch approach. This kind of treatment approach is adopted for disorders such as fibroid and certain types of cancer such as prostate cancer.
   • Your doctor will monitor your condition by asking you to undergo testing such as ultrasound or computed tomography scan and calling you for regular follow-ups. They may also order diagnostic tests to know if a particular treatment is working effectively on your disease.
3. Screening
   • A screening test is done to detect potential disorders or diseases in people who do not have any symptoms of the disease. You can ask your doctor if you can undergo a screening test for conditions such as breast cancer.
   • Your doctor can tell you if you can go for one depending on whether you have risk factors for the disease. Screening tests allow for early detection of the disease so that it can be treated right away with treatments and lifestyle changes. 
4. Prognosis
   • A diagnostic test can also help your doctor check the progression of your disease and predict how long will you live.

1. X-rays
   • X-rays involve projecting electromagnetic waves, a type of radiation on specific areas of the body to create pictures of the inside of your body.
   • They are used most commonly for detecting broken bones (fractures), osteoarthritis, and chest infections such as pneumonia. 
2. Mammograms
   • A mammogram is a term used for an X-ray picture of the breast. It is used to look for early signs of breast cancer. Sometimes, it can detect breast cancer as early as three years before it can be felt.
   • To take a mammogram of your breast, your breasts will be placed on the flat surface of a mammogram machine and will be pressed by another flat surface of the same machine from above. This step is repeated to take side views of your breast. You may feel slight pain or discomfort that lasts for only a few moments during the procedure.
3. Bone density scan (DEXA scan)
   • A bone density scan is a type of low-dose X-ray test that helps show the strength and thickness (known as bone density or mass) of your bones. It is used to detect a condition known as osteoporosis.
   • Osteoporosis is the thinning and brittleness of bones that commonly occurs with aging and after menopause (particularly after age 65 years). People with osteoporosis are at greater risk for fractures, especially in their hips, spine, and wrists.
4. Magnetic resonance imaging
   • Magnetic resonance imaging (MRI) is an imaging test that uses high-energy magnetic and radio waves to create detailed images of the organs and tissues in your body.
   • It can also produce 3D images that can be viewed from different angles as well as cross-sectional images such as slices in a loaf of bread.
   • It is most commonly used for identifying problems in the ligaments, brain, and spinal cord.
   • It can detect conditions such as ligament tears, brain tumors, and narrowing of the spinal canal (spinal stenosis).
5. Computed tomography scan
   • A computerized tomography (CT) scan uses a machine that moves over a particular section of the body and takes a series of X-rays from different angles around your body. It helps create cross-sectional images (slices) of the various tissues such as bones, blood vessels, and soft tissues inside your body. CT scan images provide more detailed images than plain X-rays.
   • A CT scan can help your doctor diagnose conditions such as bone tumors, infections, internal injuries, bleeding, and blood clot. It is widely used for detecting and monitoring diseases and conditions such as cancer.
6. Ultrasound scan (sonography or diagnostic medical sonography)
   • Diagnostic ultrasound is an imaging method that uses high-frequency sound waves to generate images of organs and blood vessels of your body. It uses a small device known as a transducer that is moved over your body or sometimes by placing inside your body.
   • It is used for diagnosing or detecting various conditions such as:
     • Gall bladder disease
     • Appendicitis (inflammation of the appendix)
     • Kidney stone
     • Thyroid problems
     • Breast lumps
     • Prostate disorders
     • Varicose veins (engorgement of veins due to problems in the valves of the veins)
     • Pregnancy (monitoring fetal growth)
     • Lumps in the uterus such as fibroid
     • Ovarian cysts
7. Electrocardiogram
   • An electrocardiogram (ECG) involves placing sensors (electrodes) over your chest to check your heart's rhythm and electrical activity. The electrodes detect the electrical signals produced by your heart with every heartbeat. These signals are recorded by a machine and printed on a piece of paper, which can let your doctor know if you have irregular heartbeats.
   • It is used in emergency conditions for quick detection of heart problems such as heart attack (myocardial infection). It is also used as the primary imaging test to identify problems in your heart.
8. 2D-Echocardiography
   • 2D-Echocardiography (2D-Echo) is a test that uses sound waves to assess the heart's function and structures. It helps the doctor know if there are problems concerning the valves of your heart such as mitral stenosis, which is narrowing of the mitral valve.
   • It can detect blockages in the arteries of your heart and damage to the muscles of your heart.
   • It lets your doctor know how efficiently your heart can pump.
9. Blood tests
   • Blood tests are used routinely in clinical practice. They can be nonspecific such as complete blood count (CBC) or specific such as thyroid function tests that detect thyroid hormone levels in your blood.
   • Different types of blood tests include:
     • CBC which includes levels of
       • Hemoglobin
       • Red blood cells
       • White blood cells
       • Platelets
     • Liver function tests 
     • Kidney function tests
     • Blood sugar levels
     • Lipid profile test that includes levels of
       • Cholesterol 
       • Triglycerides
     • HIV test
     • Bleeding time and clotting time
10. Biopsy
    • A biopsy is a surgical procedure to remove a piece of tissue or a sample of cells from your body. The sample is then sent to the laboratory to analyze the cells under a microscope.
    • The cell can be identified as cancerous or noncancerous. Thus, the test is used as a confirmatory test for cancer. 
11. Endoscopy
    • Endoscopy is the procedure that involves using a long, thin, flexible tube that has a lighted camera at one end to view the inside of an organ. The tube is known as an endoscope, and it helps create images of the inside of your body to be shown on a television screen.
    • Endoscopes can be introduced into the body through the mouth and down the throat, through the bottom (e.g., the anus), or by creating a small cut in your abdomen.
    • Depending upon the organ that needs to be viewed, endoscopy is called by various names, including:
      • Gastroscopy (endoscopy of the esophagus, the stomach, and first part of the small intestine)
      • Colonoscopy (endoscopy of the colon)
      • Bronchoscopy (endoscopy of the airways)
      • Hysteroscopy (endoscopy of the uterus)
      • Cystoscopy (endoscopy of the bladder)
    • Endoscopy can detect problems such as inflammation of the stomach (gastritis), stomach ulcers, intestinal ulcers and blockages, or tumors in the organs.