6 Common Types of Diagnostic Medical Devices

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 is found in outpatient care centers for adult and pediatrics, in emergency rooms, as well as inpatient hospital rooms and intensive care units.

blood pressure cuff on patient
Joe Raedle / Getty Images News / Getty Images

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 to adjoining stethoscopes. This last feature is important when training interns, residents, and fellows.


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

The sphygmomanometer can help diagnose:

  • Diabetes
  • High or low blood pressure
  • Artery hardening
  • Arterial plaque
  • Hypotension

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 healthcare 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:

  • Bacterial infections
  • Detached retinas
  • Glaucoma

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, makes 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.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. MedlinePlus. Breath sounds.

  2. Handler J. The importance of accurate blood pressure measurementPerm J. 2009;13(3):51-54. doi:10.7812/tpp/09-054

  3. Shahbabu B, Dasgupta A, Sarkar K, Sahoo SK. Which is more accurate in measuring the blood pressure? A digital or an aneroid sphygmomanometer. J Clin Diagn Res. 2016;10(3):LC11-4. doi:10.7860/JCDR/2016/14351.7458

  4. Kang HK, Luff AJ. Management of retinal detachment: a guide for non-ophthalmologistsBMJ. 2008;336(7655):1235-1240. doi:10.1136/bmj.39581.525532.47

  5. MedlinePlus. Otoscope examination.

  6. American Heart Association. Electrocardiogram (ECG or EKG).

By Brian Carmody
Brian Carmody was a Lieutenant and Captain in the U.S. Army Medical Service Corps, Brian trained for the delivery of medical care and supplies within the chaos of a battlefield, as well as within the structured organization of a military medical center. After his Active Duty service ended, Brian moved to the pharmaceutical industry and in the healthcare furniture, equipment, and supply distribution industry.