Common Types of Diagnostic Medical Devices

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Diagnostic medical equipment and supplies help clinicians to measure and observe various aspects of a patient's health so that they can form a diagnosis. Once a diagnosis is made, the clinician can then prescribe an appropriate treatment plan.

Diagnostic medical equipment are found in outpatient care centers for adult and pediatrics, in emergency rooms, as well as inpatient hospital rooms and intensive care units.

The following list is not exhaustive, but it provides an overview of some of the most commonly used diagnostic tools.


Stethoscopes are probably the most recognizable of all medical diagnostic tools. They are used to listen to heart sounds, the lungs, and even blood flow in the arteries and veins.

Stethoscopes help diagnose:

Stethoscopes are also used along with a sphygmomanometer to measure blood pressure.

Electronic Stethoscopes improve sound quality when listening to the low-pitched heart sounds and the high-pitched pulmonary sounds. They can be connected to a computer to record and save the sounds. They can be hooked up to distributors that allow multiple people to listen on adjoining stethoscopes. This last feature is important when training interns, residents, and fellows.


Evidence-based medicine has proven that the measure of blood pressure is important in determining the overall health of a person.

The sphygmomanometer can help diagnose:

High blood pressure has been linked to several diseases. There are a few products that are used to measure blood pressure.

Manual sphygmomanometers are considered the most reliable. Mercury manometers don't require routine calibration and therefore are used in high-risk scenarios.

Aneroid sphygmomanometers are a little less reliable because they can lose their calibration when bumped, which can be a common occurrence in health care settings. Wall-mounted styles can reduce this possibility, but should still have calibration checks to be sure. The aneroid style is easily identified as a mechanical unit with a dial for the readings, as well as a bulb and air valve.

Digital finger blood pressure monitors are the smallest and most portable. While easy to operate, they are a bit less accurate.

Digital sphygmomanometers, like the digital finger blood pressure monitors, are also electronic. They can be inflated either manually or automatically. They are easy to use, but derive blood pressure in an indirect way. Digital units measure mean arterial pressure, which basically translates into an average of the systolic and diastolic pressure. The digital sphygmomanometer then must derive what the systolic and diastolic readings would be. These are helpful in noisy areas where the manual mercury manometers would prove ineffective because of the need for the clinician to hear the Korotkoff sounds.


Ophthalmoscopes are handheld tools that allow a physician to see into the fundus of a patient's eye. This type of diagnostic tool is commonly used in physical or outpatient exams.

Ophthalmoscopes can help diagnose:

There are two types of ophthalmoscopes.

Direct ophthalmoscopes produce an upright image of approximately 15 times magnification. These tools are held as close to the patient's eye as possible.

Indirect ophthalmoscopes produce an inverted image of 2 to 5 times magnification. Indirect ophthalmoscopes are held 24 to 30 inches from the patient's eye. Indirects also have a more powerful light so they are more effective than directs when used in patients with cataracts.


Otoscopes are handheld devices that allow physicians to look into the ear canal and view the tympanic membrane through the magnification lens. 

Otoscopes help diagnose:

The head of the otoscope also has a light. The light, together with the magnifying lens, make it possible to view the outer and middle ear. The portion that the physician inserts into the ear canal is called the disposable speculum. Disposable specula are stored in a dispenser in the exam room so that a new, clean one can be attached to the otoscopes for each patient.


Electrocardiographs measure the electrical activity of the heart. During this examination, heart rate can be recorded, as well as the regularity of the beats. These are two key indicators of any issues in the heart. Physicians can even read an electrocardiograph to determine the size and position of each heart chamber. And finally, a major use for the electrocardiograph is to diagnose damage to the heart, and the impact and efficacy of drug treatment or device implant.


Thermometers are used in all areas and levels of care, from routine physical exams to emergency department triage to inpatient care. There are now electronic thermometers that shorten the time necessary to measure a patient's temperature. The electronic ones can be set for the specific part of the body being measured, such as the mouth, under the armpit, rectally, or the ear.

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