September 12, 2023
September 12, 2023

Screening vs Diagnostic Tests: What You Need to Know

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Screening vs Diagnostic Tests: What You Need to Know

Editor’s note: This blog post was medically reviewed by Carol DerSarkissian, MD.

Ever wondered about the difference between a screening and a diagnostic test?

Screening tests such as a full-body MRI scan help find problems early on when they may be easier to treat and possibly improve outcomes.

For example, cancer screening for at-risk patients helps in the early detection of potential abnormalities before they become advanced, aiding medical professionals in offering timely treatment and potentially saving lives.

On the other hand, diagnostic tests often come after screening tests and either confirm or eliminate the findings from screening results.

In this guide, we’ll cover what screening and diagnostic tests are, provide examples, and detail the differences between the two.  

Table of Contents

What Is a Diagnostic Test?  

Diagnostic tests help health professionals determine the causes of illness or injury in their patients, confirm a diagnosis, or monitor changes in a disease after treatment. These tests are used to examine possible root causes of particular symptoms or a specific health concern, such as cancer.

The purpose of diagnostic tests is to detect the presence or absence of disease. It is only warranted if the results of a diagnostic test can provide meaningful clinical information for doctors on the patient’s response to treatment, status, and prognosis.

As an example, a healthcare provider may request a diagnostic mammogram to examine a breast lump found after a screening mammogram, and check the abnormal lump for possible breast cancer.

Multiple techniques may be used for diagnostic testing, including blood work, biopsy, and other imaging scans.

Examples of Diagnostic Tests

Here are some examples of the most commonly performed diagnostic tests.


A diagnostic technique performed by examining a sample of tissue taken from a patient’s body, a biopsy is used to determine whether an area of abnormal tissue is benign or malignant (cancerous).

Blood tests

Blood tests, also known as blood work,  involve taking a sample of blood from a person’s body. The blood sample will be checked for specific proteins, chemicals, cells, and other substances.

As one of the most common types of tests, a blood test is used to diagnose certain conditions like leukemia, infection, and bleeding disorders.


This type of digital diagnostic testing shows real-time X-ray scans of internal body structures, highlighting any signs of irregularities as medical professionals examine the movement of body systems.

Ultrasound (Sonography)

This type of test allows health professionals to see inside the human body using high-frequency sound waves.

Other imaging tests like an MRI and a CT scan are both diagnostic and screening in nature. You will learn more about these tests below.

See more examples of diagnostic tests by the National Library of Medicine.

What About a Screening Test?

Screening programs, on the other hand, are often conducted on asymptomatic patients. These tests are performed on people who have not shown any signs of disease or health issues requiring further examination or diagnosis.

Health screening tests are used primarily to evaluate the likelihood of a patient having or developing particular diseases, such as cancer. These screenings aid in identifying asymptomatic individuals at risk for particular health issues. Risk factors for cancer include family history, genetics, and the general wellness of the individual.

Preventative health screenings provide patients with direction for either follow-up testing to reach a confirmed diagnosis, specific treatment or a change in lifestyle habits that further promote wellbeing.

Repeat screenings, such as the Ezra full-body MRI, can help monitor your body across time and flag any abnormalities early, which can have significant and sometimes life saving consequences.

Repeat screenings, such as the Ezra full-body MRI, can help monitor your body across time and flag any abnormalities early, which can have significant and sometimes life saving consequences.

Examples of Screening Tests

Here are some examples of preventative screening tests a medical professional may recommend.

It’s worth noting that there are certain screening tests that can also be used to help diagnose a condition.  For example, a mammogram can be done either for diagnostic or screening purposes. The same goes for MRI and CT scans.


Magnetic resonance imaging (MRI) tests utilize radio waves and magnetic waves to create detailed, cross-sectional pictures of a patient’s body.

A 2019 review pointed to MRI as the most important modality in the imaging of soft tissue tumors. The review described how MRI allows a more detailed classification of the tumor and, in many cases, a differentiation between benign and malignant masses.

A 2019 review pointed to MRI as the most important modality in the imaging of soft tissue tumors. The review described how MRI allows a more detailed classification of the tumor and, in many cases, a differentiation between benign and malignant masses.

CT Scans

Similar to an MRI, computed tomography (CT) scans use X-rays to take images of body tissues and organs from various angles. As a medical diagnostic tool, CT scans can help determine causes of cancer, as well as monitor tumor growth after treatment.

As outlined in a 2020 trial study, CT scans seem to be linked to a lower mortality rate for patients at high-risk for lung cancer.

Learn moreElective CT Scan vs. MRI: Which Should You Choose?


A colonoscopy screens a patient for rectal and colon cancer, and alerts healthcare providers to the presence of swollen tissue, polyps, and cancerous tumors.


Specific to breast cancer screening, a mammogram diagnostic test is powerful for examining and monitoring individuals for breast cancer.

Learn moreMammogram vs. Ultrasound for Early Breast Cancer Detection

When is a Screening Test Helpful?

Doctor helping patient

Screening tests can be a valuable tool in detecting potential health issues early on. However, it’s important to note that they aren’t always accurate and further testing may be required.

As a general rule, follow your healthcare provider’s guidance on when to schedule these tests to make the most of their benefits.

In some cases, such as for individuals not at high risk for a certain disease or very rare conditions, undergoing screening tests can cause more problems than it solves.

Screening vs Diagnostic Tests: The Differences

What’s the difference between preventative screening and diagnostic imaging?

The answer is found in the words themselves (“screening” and “diagnostic”) and the purpose of the two types of medical imaging:

  • Preventative screening can identify the potential progression of diseases before symptoms occur. However, it’s important to note that the screening itself does not prevent the disease – it only highlights the need for further steps to be taken.
  • Diagnostic tests aid in diagnosing a medical issue that already exists

Screening and diagnostic testing are often done together. A preventative screening test checks to see if your health and well-being are optimal, and a diagnostic test is performed to confirm or learn more about the abnormalities that were detected.

Here’s a quick comparison of the two tests and what to expect with each.

ComparisonScreening TestsDiagnostic Tests
Who is it for?For patient without symptoms
  • For patients who do experience symptoms
  • For patients whose screening results shows abnormalities
What is it for?Used to detect possible disease before they become serious health issuesUsed to diagnose already existing medical concerns
When to considerOften used as routine testing for disease preventionPerformed as soon as a screening detects abnormalities
When is it recommended? May be recommended for individuals at risk for particular diseases, such as cancerUsed as a tool to determine root causes of existing symptoms, or monitor treatment or changes in a disease

While diagnostic tests are crucial for accurate medical treatment, screening tests are valuable because they help healthcare providers detect potential problems.

With the rise of direct screening options open to the public, such as full-body MRI scans, patients can access medical screening themselves, and take better control of their health.

What Conditions May Require Screening and Diagnostic Testing?

Screening tests are often performed on individuals who are at risk for chronic diseases, such as cancer, heart diseases, or diabetes. Diagnostic tests are ordered by doctors when symptoms or health issues arise that require more examination before a clear prognosis can be made. Medical interventions will also depend on diagnostic test results.

Screening tests help detect abnormalities before any diagnosis is made. Once abnormalities have been detected, a diagnostic test may be required to determine proper future treatment.

Health professionals may screen for the following medical conditions:

  • Breast cancer and cervical cancer in women
  • Colorectal cancer
  • Osteoporosis (loss of bone density)
  • Prostate cancer in men
  • Heart disease
  • Carotid artery disease
  • Lung cancer
Did you know?

In less than an hour, Ezra’s full-body MRI screens up to 13 organs for potential cancers or other abnormalities.

The Ezra Full-Body Scan: Which Is It?

Doctor helping patient in MRI machine

Our full-body MRI scan is a screening test that helps you stay ahead of potential health concerns by screening for potential abnormalities.

Ezra’s full-body scan falls under the preventative screening category. This means that the imaging results can guide you toward further diagnosis, medical treatment (when needed), and assist you in establishing healthy lifestyle habits that ensure your wellbeing.

Learn more: Cancer warnings that may appear on an Ezra screening.

Our modern MRI equipment, well-trained MRI technologists, and Care Advisors will guide you through the process of signing up and getting your scan.

In addition, a board-certified radiologist will provide you with a report of your MRI results and our Medical Providers will provide you with an Ezra Report, which translates your findings into straight-forward language and discusses next steps and recommendations.

Take the next step in your health journey and be proactive with our routine MRI screening scans. Give the gift of a full-body MRI scan to a loved one today, or book an appointment for yourself.

Not yet ready for a scan? Calculate your cancer risk in 5 minutes or less.