Along the same lines as Ajit;
Post-market activities can be divided in two categories:
1. Proactive - Post Market Surveillance
2. Reactive - Vigilance
Post-Market Surveillance is defined as: "the pro-active collection of information on quality, safety or performance of Medical Devices after they have been placed on the market."
Regulatory authorities allow medical devices to be placed on the market based on data supporting the reasonable assurance that the proposed device is both safe and effective. These data comprise prospective premarket information generated by using ideal devices under ideal conditions. Retrospective post-market data derived from devices and conditions may differ from the premarket testing in ways both obvious and subtle. An effective post-market surveillance program monitors the performance of the full range of actual devices under all actual usage conditions, to ensure that the assumptions and estimates applied during the product development process were accurate and remain so throughout the total product lifecycle.
Conversely, Post-Market Vigilance refers to incidents that can occur with medical devices when they do not perform as intended, thereby leading in the worst case to injury or death. The medical device directives require timely, coordinated action and provision of information between the manufacturer and the regulatory authorities in relation to (near) incidents that are related to the device.
The purpose of medical device vigilance is to protect the health and safety of patients; evaluate incidents to prevent recurrence; determine the effectiveness of corrective actions and preventive actions; and monitor and learn from experience.