The Most Common Medical Diagnostic Tests

The Most Common Medical Diagnostic Tests

Doctors use a variety of tools to identify illnesses, injuries, and other medical conditions that may require specific treatment. Many things, from the basic thermometer and blood pressure cuff to sophisticated laboratory processes, can reveal what ails a patient. The most common medical diagnostic tests may take place in the doctor’s office or in a specialized department with sophisticated testing equipment.

Remember, if you don’t feel well, call your doctor to seek medical advice about your next steps.

Physical Exam

The basic physical exam is itself a kind of diagnostic test. The doctor examines a patient’s body for signs of injury or disease that aren’t readily apparent. The annual physical exam most adults undertake can alert doctors to conditions that indicate the possible presence of disorders requiring treatment, even when the patient feels just fine. Most patients recognize the routine from their earliest experiences of wellness checks. Looking into eyes and ears, saying “aaaahh” so the doctor can look at the throat, and that little rubber hammer that tests reflexes all perform common medical diagnostic tests.

Blood and Urine Tests

These tests can identify the presence or absence of infections or imbalances in blood gasses and chemicals that could indicate disease. That “CBC” you hear on medical dramas on television refers to “complete blood count.” The CBC test is a common diagnostic tool to check on the status of components of the blood—red and white cells and platelets for clotting. A medical professional takes a sample of blood (or the patient provides a sample of urine), and these go to the lab for analysis. Tests like these are called “in vitro diagnostic” or IVD tests. Although the term “in vitro” has become associated primarily with reproductive health, many diagnostic tests performed outside the body are called IVDs. The design and manufacture of these kinds of tests are regulated for public health and safety.


Technology that helps doctors look inside the body has been around for a long time, but it has advanced rapidly in recent decades. X-rays that use radiation to get a picture of the area of interest are common medical tests to identify injuries or the presence of tumors or abnormalities, such as with mammography. On the other hand, newer types of imaging use magnetic resonance imaging (MRI scans) and radio waves to get a better picture of structures within the body, particularly soft tissues. Positron emission tomography (PET scan) looks at how organs are functioning. PET scans help in determining blood flow and metabolism.

Other imaging tests use cameras that are inserted into the body to examine the upper and lower intestinal tracts or look for signs of disease, as in the colonoscopy to check for signs of colon cancer. Sound is another way to create an image of what is within the body, as many expectant parents know from ultrasound tests that produce an image of their baby in the womb.

These are just a few of the most common types of diagnostic tests. When doctors suspect serious conditions, they may order additional, more involved blood tests or biopsies to take a tissue sample and check for cancerous conditions.

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