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What Does 'Non-invasive' Mean?

Non-invasive simply means the body is not invaded or cut open as during surgical investigations or therapeutic surgery. Until the last several decades, exploratory surgery was routinely performed when a patient was critically ill and the source of illness was not known. In dire cases, the patient's thorax, for instance, was surgically opened and examined to try to determine the source of illness. Diagnostic imaging was first performed in 1895 with the discovery of the x-ray. For the first time, physicians could see inside the body without having to perform exploratory surgery. Thus diagnostic imaging is a "non-invasive" way to look at internal organs and structures.

Using Non-invasive Imaging to Guide Minimally Invasive Therapy

Many therapeutic methods still require fully invasive surgery. Some spinal surgery, for instance, still requires the physician to open the patient's back and remove diseased spinal disks with a scalpel. However, diagnostic imaging is now being used in conjunction with new types of minimally invasive surgery to achieve the same therapeutic goal. CT (CAT) scanning can be used to guide the execution of minimally invasive back surgery (e.g. thoracic sympathectomy). The outcome is positive therapy while minimizing potentially detrimental surgical trauma to a patient.

X-ray Angiography has progressed over the years as a diagnostic tool to image the blood vessels and heart. In recent years diagnostic angiography is being performed more often with MR (MRI), CT or Ultrasound angiography techniques while x-ray angiography isbeing used as an interventional tool to perform minimally invasive vascular and cardiac surgery. Using angiography to see inside, doctors can repair blood vessels without the use of fully invasive methods. Advances in the design and use of catheters (small tubes that are guided into the blood vessels via tiny incisions in the groin area or arm) allow physicians to perform very complex therapeutic procedures from within the blood vessel.

Replacing Coronary Bypass with Coronary Angioplasty

Coronary bypass surgery is a common, but invasive surgical procedure in the U.S. and is performed over 200,000 times per year at an average cost of about $25,000. During bypass surgery, synthetic blood vessels or vessels grafted from other parts of the body are used to create an alternative passage. This new vessel or "bypass" functions in place of the clogged blood vessel to feed the heart's tissue with blood, nutrients and oxygen. However, a new technique called coronary artery angioplasty can be performed without invasive surgery. In this method, angiography is used to guide surgical stents (small cylindrical supports) into place in order to re-open clogged blood vessels.

Traditionally, invasive or open surgery required inpatient hospital admission at an acute care hospital. However, many invasive surgery procedures that were done on an inpatient basis have been replaced by outpatient techniques. What is the difference between outpatient and inpatient medicine?

Updated: September 13, 2007