Doctor-Reviewed Health Guides: Conditions, Procedures & Health News

A Doppler ultrasound is a painless imaging test that uses sound waves to show how blood moves through your arteries and veins. It measures the speed and direction of blood flow, so doctors can find blood clots, narrowed or blocked vessels and other circulation problems in the legs, arms, belly, neck and heart. It needs no needles, dye or radiation.

A chlamydia test checks for the bacteria that cause chlamydia, the most common bacterial sexually transmitted infection (STI). Most tests use a urine sample or a swab. Results are ready in about 24 hours. Because chlamydia often causes no symptoms, screening matters, especially if you are sexually active and under 25. Avoid sex while you wait for results.

A blood urea nitrogen (BUN) test measures how much urea nitrogen, a waste product made when the body breaks down protein, is in the blood. A high level can mean the kidneys are not working well. Normal ranges are 7 to 20 mg/dL in children, 6 to 21 in adult females and 8 to 24 in adult males.

A cystoscopy is a procedure in which a urologist slides a thin, lighted scope (cystoscope) through the urethra into the bladder to look at the lining of both. It's used to find the cause of symptoms such as blood in the urine or painful urination and to treat some problems. A diagnostic cystoscopy takes 5 to 10 minutes.

A positron emission tomography (PET) scan is an imaging test that shows how the organs and tissues are working. A radioactive tracer is injected into a vein, and a scanner detects cells that absorb large amounts of it, which can signal disease. PET scans help find and track cancer, heart disease and brain conditions. The visit takes 2 hours.

An endoscopy is a procedure that lets a provider look inside the body using an endoscope, a thin tube with a light and camera. The scope goes in through a natural opening, such as the mouth or anus, or a small incision. Providers use it to screen for, diagnose and treat conditions. Most people go home the same day.

An HPV test checks cells from the cervix for the high-risk strains of human papillomavirus (HPV) that can cause cervical cancer, including HPV 16 and HPV 18. People with a cervix aged 30 to 65 should be screened regularly, and a normal result means retesting in 5 years. A positive result does not mean you have cancer.

A CT (computed tomography) scan, also called a CAT scan, is a painless imaging test that takes many X-ray pictures from different angles and uses a computer to combine them into detailed images of the bones, organs and soft tissues. It helps diagnose cancer, injuries, infections and blood clots. The scan itself usually lasts less than 5 minutes.

An RDW (red cell distribution width) blood test measures how much your red blood cells vary in size and volume. It's reported as part of a complete blood count (CBC). A typical result falls around 12% to 15%, though ranges vary by lab, and a high RDW may point to anemia or a related condition.

An ALT blood test measures alanine transaminase, an enzyme found mostly in the liver. When liver cells are injured, ALT can leak into the bloodstream, so a high result can be an early sign of liver damage. One common normal range is 7 to 56 U/L, but ranges vary by lab, and one result alone is not a diagnosis.

An X-ray is a quick, painless imaging test that uses a small amount of radiation to make pictures of the inside of your body. It's used most often to check bones and joints, but it can also look at your chest, belly, spine, head and teeth. A radiologist reviews the pictures and sends a report to your provider.

An echocardiogram, often shortened to "echo" or called a heart ultrasound, is an imaging test that uses high-frequency sound waves to create pictures of your heart. It shows the heart's structure, how well it pumps and how blood flows through its chambers and valves. Most echoes are noninvasive and use no radiation.

An alkaline phosphatase (ALP) test is a simple blood test that measures how much of the ALP enzyme is in your blood. Most ALP comes from the liver and bones, so the test helps screen for, diagnose and monitor liver, bile duct and bone conditions. It cannot diagnose a condition on its own.

An MRI is a painless imaging test that uses a large magnet, radio waves and a computer to create detailed pictures of soft tissues such as the brain, nerves, muscles, ligaments and organs. It uses no radiation, takes about 30 to 60 minutes, and is low risk when safety screening for metal and implants is followed.

A color blind test, more accurately called a color vision test, checks whether you have color vision deficiency and, if so, which type and how severe it is. You look at colored plates, cards or screen images and say what you see, or arrange or match colors. It is quick and painless.

Pulmonary function tests (PFTs) are noninvasive breathing tests that show how well your lungs work. They measure how much air you move in and out, how well gas passes from your lungs into your blood and how your lungs cope with exercise. Most tests take 15 to 45 minutes, don't hurt, and results come back within a few days.

Your heart rate is the number of times your heart beats in one minute. For adults and teens, a normal resting heart rate is about 60 to 100 beats per minute (bpm), while babies and young children run faster. You can check it by counting your pulse at the wrist for one full minute.

A mammogram is an X-ray of your breast tissue. It is used both to screen people with no symptoms and to look more closely at a breast problem, and it can reveal early changes linked to breast cancer before you notice anything yourself. A mammogram cannot confirm cancer on its own, so an unusual finding leads to more imaging.

A comprehensive metabolic panel (CMP) is a common blood test that measures 14 substances in the blood, including proteins, enzymes, electrolytes and blood sugar. Together, these results give a snapshot of how the liver and kidneys are working, how fluid and acid balance looks and how the body handles glucose. It's often part of routine care.

A semen analysis is a lab test that looks at a semen sample under a microscope to check how many sperm there are, how well they move and what shape they are. It's one of the first tests used when a couple has trouble getting pregnant, and it also confirms whether a vasectomy has worked.

STD testing (also called STI testing) is a group of tests that check whether you have a sexually transmitted infection. Depending on the infection, your provider may use a blood sample, a urine sample, a swab or a physical exam. Many STIs cause no symptoms, so testing is often the only way to know your status and get treated early.

An eye exam is a painless, noninvasive check of how well you see and how healthy your eyes are, done by an optometrist or ophthalmologist. A comprehensive exam covers 13 areas, from reading a letter chart to looking at the retina and optic nerve. Most people should have one every one to two years, even with 20/20 vision.

An electrolyte panel is a routine blood test that measures the charged minerals that keep your body's fluids, pH, nerves and muscles working. The core panel checks sodium, potassium, chloride and bicarbonate. It is often part of a basic or comprehensive metabolic panel and helps find fluid and acid-base imbalances. [1, 2]

A DXA scan, often still called a DEXA scan, is a quick, painless imaging test that uses two low-level X-ray beams to measure how dense your bones are. It usually checks the hips and spine, and it helps diagnose osteoporosis and osteopenia, estimate fracture risk and track whether bone treatment is working.