non-invasive in medicine has two meanings:
For centuries, physicians have employed many simple non-invasive methods based on physical parameters in order to assess body function in health and disease (
physical examination and inspection), such as pulse-taking, the auscultation of heart sounds and lung sounds (using the stethoscope), temperature examination (using thermometers), respiratory examination, peripheral vascular examination, oral examination, abdominal examination, external percussion and palpation, blood pressure measurement (using the sphygmomanometer), change in body volumes (using plethysmograph), audiometry, eye examination and many others.
However, since the discovery of the first modern non-invasive techniques based on physical methods,
electrocardiography and x-rays, at the end of the 19th century, medical technology has advanced more and more towards non-invasive methods for diagnosis and therapy, such as:
Additional recommended knowledge
A recent advance is the substitution of
invasive medical tests, such as colonoscopy by computer-based 3D reconstructions, such as virtual colonoscopy.
Radiation therapy and radiosurgery, procedures that uses external atomic particles (protons, neutrons, photons, alpha particles, etc.) or gamma rays to destroy pathological tissue within the body
Lithotripsy, a procedure that uses ultrasound shock waves to break urinary calculus
Defibrillation, a procedure to block heart fibrillation and start normal rhythm
Mechanical ventilation, such as the iron lung.
Transdermal patches, used to deliver drugs applied to the skin.
CPAP (Continuous Positive Airway Pressure) used to treat sleep apnea
Biphasic Cuirass Ventilation (BCV, eg. Hayek RTX)
Extracorporeal thermal ablation
Extracorporeal magnetic innervation 
Photo-infrared pulsed bio-modulation 
Transcranial magnetic stimulation
In some cases, non-invasive methods will not work for the intended purpose, so medical technology has developed
minimally-invasive methods, such as hypodermic injection (using the syringe), endoscopy, percutaneous surgery, laparoscopic surgery, coronary catheterization, angioplasty, stereotactic surgery and many others.
The benefits for the patient are self-evident.
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