What is a screening test?

A screening test is done to find possible health problems or diseases in people who don't have any symptoms of disease. The goal is to find a problem early enough to lower the risk for the disease . Or to find it early enough to treat it before it gets worse.

Healthcare providers don’t use screening tests to diagnose disease. But screening tests help to see if someone may need more testing to find out if they have a disease or other health problem.

When is a screening test helpful?

A screening test is helpful when it can clearly find a possible problem. A screening test works when the results clearly show that there is or isn’t a problem. Screening tests are not 100% accurate in all cases. But having them as advised by your healthcare provider is better than not having them at all. Some screening tests can cause more problems than they help if used in people who aren’t at high risk for disease, or for very rare diseases. This is one of the reasons recommended screening tests are not the same for every person.

Some common screening tests

Talk with your healthcare provider about when to get screening tests. Your provider will base the schedule on your age, overall health, family health history, and personal health history. Below are some examples of common screening tests.

Cholesterol screening

Cholesterol is a waxy, fatlike substance. It can be found in all parts of the body. It helps your body make cell membranes, some hormones, and vitamin D. The cholesterol in your blood comes from two sources: from the food you eat and from your liver. Your liver makes all the cholesterol your body needs.

Cholesterol and other fats are carried in the bloodstream as spherical particles. They are called lipoproteins. The 2 most commonly known lipoproteins are low-density lipoproteins (LDL), or "bad" cholesterol, and high-density lipoproteins (HDL), or "good" cholesterol.

Cholesterol screening is done with a blood test. If your cholesterol results are high, you may have a higher risk for cardiovascular disease than people with cholesterol in the normal range. You may lower your risk for heart disease by lowering your cholesterol. But keep in mind that you can still have heart disease even with cholesterol levels in the normal range.

Fecal occult blood test

Fecal occult blood is found by looking for it with a microscope or by using chemical tests for blood (hemoglobin) in the stool. People with blood in their stool may have a growth that may be colorectal cancer. For the test, you collect 3 stool samples. The samples are looked at under a microscope for blood.

Blood in the stool may be caused by things other than cancer. It may be caused by certain medicines or foods, bleeding in your digestive tract, or hemorrhoids. The American Cancer Society recommends starting this test at age 45 if you are at average risk for colorectal cancer.

Pap test

Pap tests, or Pap smears, are samples of cells taken from your cervix. The sample is looked at under a microscope. They check for any changes that might mean cervical cancer. The Pap test is an important screening test in sexually active females younger than 65. It can find cancer at a stage when there are often no symptoms. Even if your Pap results are abnormal, that may not mean you have cervical cancer. Some expert groups also recommend screening for HPV (human papillomavirus) at the same time as the Pap test is done. 

Prostate-specific antigen (PSA) test

This blood test measures the prostate-specific antigen (PSA) levels in the blood. Antigens are any substances that make your immune system react. PSA levels can be higher than normal if you have prostate cancer. But other problems can cause a high PSA level. These include benign prostatic hyperplasia (BPH). BPH is not cancer. It is when your prostate is enlarged. The PSA test is not recommended for all males. Expert groups disagree on whether the PSA test is needed. Some groups, such as the U.S. Preventive Services Task Force (USPSTF), now recommend against PSA screening for males 70 years of age or older. For ages 55 to 69, it is recommended that you discuss the pros and cons of PSA screening with your healthcare provider. Some of the cons include unneeded testing and procedures, extra costs, and anxiety.

Mammogram

Many expert groups, including the USPSTF, recommend mammograms for breast cancer every 2 years for ages 40 to 74 for those at average risk. This test is done along with a clinical breast exam. The American Cancer Society recommends females ages 45 to 54 at average risk for breast cancer get a mammogram every year.

Colonoscopy and other screenings for colon cancer

For people at average risk, the American Cancer Society and USPSTF recommend that colorectal screening start at age 45.

Multiple tests are available and are used at different times. They are:

• Flexible sigmoidoscopy every 5 years

• CT colonography (virtual colonoscopy) every 5 years

• Colonoscopy every 10 years

• Fecal occult blood test or fecal immunochemical test every year

• Stool DNA test every 3 years

You will need a follow-up colonoscopy if you choose any other test but colonoscopy and have an abnormal test result. Talk with your healthcare provider about which tests are best for you.

Some people should be screened using a different schedule because of their personal or family history. Talk with your healthcare provider about your health history.

Diabetes or prediabetes screening

The American Diabetes Association recommends that all adults be screened for diabetes or prediabetes starting at age 45. This is true no matter how much you weigh. You should also get screened if you are overweight or obese and have one or more other risk factors for diabetes. 

Talk with your healthcare provider about all these tests, as well as your family's health history and other types of screening tests. Not all providers agree on which screening tests should be done for different age groups.