What is the classification of contrast venography in terms of invasiveness?

Contrast venography is classified as invasive because it involves the introduction of a contrast agent directly into the venous system through a catheter. This procedure typically requires the use of needles or catheters which penetrate the skin and enter the vascular system. As a result, it carries some risks, such as bleeding, infection, or allergic reactions to the contrast material.

In contrast, non-invasive procedures generally do not involve any penetration of the skin or entry into the vascular system, relying instead on external imaging techniques. Minimally invasive procedures might require small incisions or punctures, but they often focus on reducing recovery time and discomfort compared to traditional surgeries, which is not the primary characteristic of contrast venography. Finally, while contrast venography can be diagnostic, the terminology of "diagnostic only" does not categorize its invasiveness, as the focus is on the method's technique and its direct implications for patient safety and procedure implementation.