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

A Gram stain is a quick laboratory test that checks a sample from a suspected infection for bacteria, and sometimes fungi. Dyes color bacteria purple (gram-positive) or pink to red (gram-negative) depending on their cell walls. Results come back faster than a culture and help your provider choose an antibiotic while waiting for the culture to grow.

The O'Brien test, also called the active compression test, is a physical exam for shoulder pain. You hold your arm out and push up against the provider's hand, first with the thumb down and then palm up. Pain with the thumb down that eases with the palm up points to a SLAP tear or an AC joint problem.

A fetal fibronectin (fFN) test checks a swab of vaginal fluid for fetal fibronectin, a protein that helps hold the amniotic sac to the uterus. It's done between 22 and 34 weeks of pregnancy when there are signs of preterm labor. A negative result means you're very unlikely to deliver in the next one to two weeks.

A biophysical profile (BPP) is a prenatal test that checks a fetus's health, usually after 32 weeks. It combines an ultrasound that scores body movement, muscle tone, breathing movements and amniotic fluid with a nonstress test of the fetal heart rate, for a maximum score of 10. It takes 30 to 40 minutes and carries no risk.

A bone scan is a nuclear medicine test that checks the bones for damage or unusual activity. A small amount of radioactive tracer is injected into a vein, collects in areas of changing bone and shows up as bright hot spots on images. It's used most often to check whether cancer has spread to the bones.

Body plethysmography is a noninvasive pulmonary function test done inside a sealed, see-through booth. As you breathe through a mouthpiece, sensors calculate your total lung capacity, the air left in the lungs after breathing out and airway resistance. It takes about 15 minutes, is painless and helps diagnose and monitor asthma, COPD and pulmonary fibrosis.

A Weber test is a hearing check that uses a tuning fork placed on the middle of the forehead or the top of the head. If the sound is louder in the ear with hearing loss, that points to conductive hearing loss; if it's quieter there, that points to sensorineural hearing loss. It's often paired with a Rinne test.

The Thompson test, also called the calf squeeze test, is an in-office exam for a torn (ruptured) Achilles tendon. You lie face down while the provider squeezes your calf. If the foot moves, the tendon is likely intact; if it doesn't, the tendon may be torn. You'll usually still need an ultrasound or MRI to confirm the diagnosis.

Optical coherence tomography (OCT) is a quick, noninvasive scan that uses reflected infrared light to create cross-section images of the back of the eye, including the retina and optic nerve. It helps diagnose and track glaucoma, diabetes-related retinopathy and macular degeneration. The scan takes a few minutes, nothing touches the eye, and it has no known risks.

A dexamethasone suppression test (DST) measures how the cortisol level responds after you take dexamethasone, a man-made version of cortisol. In Cushing syndrome the level stays high. In the overnight test, you take a 1 mg pill at 11 p.m. and have blood drawn at 8 a.m. Below 1.8 mcg/dL is normal.

Cervical cancer screening checks for early cervical cancer and precancerous cell changes before you have symptoms. People at average risk should be screened from age 21 to 65: a Pap test every 3 years from 21 to 29, then a Pap test every 3 years or an HPV test or cotest every 5 years.

A venogram (venography) is an X-ray test that uses contrast dye and live imaging to show blood flowing through the veins, most often in the legs, pelvis and upper arms. Providers use it to find blood clots such as deep vein thrombosis when ultrasound can't give a clear answer. It takes 30 to 90 minutes, and you stay awake.

A hand X-ray (radiograph) is a fast, painless imaging test that makes a black-and-white picture of the inside of the hand. It helps providers find broken bones, foreign objects, arthritis, bone tumors and abnormal bone growth. The test takes 5 to 10 minutes, uses a very small dose of radiation, and results are ready within one to two days.

A sonohysterogram (SHG), also called saline infusion sonography, is a transvaginal ultrasound in which saline is passed through the cervix into the uterus so the provider can see the uterine cavity and lining clearly. It helps find the cause of abnormal bleeding, infertility and repeated miscarriages. It takes 30 to 45 minutes and causes mild to moderate cramping.

Vestibular testing is a set of tests that check how well the balance system in the inner ear works. It's ordered for dizziness, vertigo or feeling off balance and can show whether the cause is in the inner ear or the brain. The appointment lasts two hours, the tests are considered safe, and dizziness may linger briefly afterward.

Fine-needle aspiration (FNA), also called a fine-needle biopsy, uses a thin needle and syringe to remove cells, tissue or fluid from a suspicious lump or abnormal area. It's the least invasive type of biopsy and is most often used for new lumps in the breast, thyroid, lymph nodes and skin. Soreness or bruising fades within a couple of days.

A cerebral angiogram is a minimally invasive test that shows problems with the blood vessels in and around the brain. A specialist passes a catheter through an artery, injects contrast dye and takes X-rays. It can find brain aneurysms, arteriovenous malformations and narrowed or blocked arteries. Serious problems are rare; stroke happens in fewer than 1% of cases.

A mental status exam is a structured way for a provider to check how you think, feel and behave. Through observation and questions, the provider looks at your appearance, behavior, speech, mood, thoughts, judgment and cognition. The results can point toward mental health or neurological conditions, but a diagnosis also needs your history, a physical exam and other tests.

The Revised Cardiac Risk Index (RCRI) is a scoring tool used before non-heart surgery to estimate the chance of heart complications, such as a heart attack or cardiac arrest. You get one point for each of six risk factors. A score of 0 or 1 means a risk below 1%, while 3 or more points means about 11%.

An abdominal aortic aneurysm (AAA) screening is a painless ultrasound that checks for a bulge in the aorta in the belly. AAAs grow slowly with no symptoms until they burst, which is often fatal. A one-time screening is recommended for people aged 65 to 75 at highest risk, including those with a history of tobacco use.

An implantable loop recorder (ILR) is a small heart monitor that a cardiologist places under the skin of the chest. It watches the heart rate and rhythm around the clock, usually for up to three years. It helps diagnose arrhythmias, such as AFib, and causes of palpitations or fainting that an EKG or short-term monitor could not catch.

Tympanometry is a painless test that checks how well the middle ear works. A probe in the ear changes the air pressure and plays a tone while a device measures how the eardrum moves. It helps find causes of hearing loss such as fluid behind the eardrum, ear infections or blocked eustachian tubes. It takes a few minutes.

A CT urogram is a type of CT scan that uses contrast dye, X-rays and a computer to make detailed 3D images of the urinary system: the kidneys, ureters and bladder. It helps diagnose stones, infections, cysts and tumors. The scan is painless, the visit takes about an hour, and most people get results within a few days.

An ACTH stimulation test, also called a cosyntropin stimulation test, checks how well your adrenal glands make cortisol when they are signaled to. You get a shot of synthetic ACTH (cosyntropin), and blood samples taken before and after, usually at 30 and 60 minutes, measure your cortisol. It is the main test used to diagnose adrenal insufficiency.