Calibration is the most necessary thing that helps in minimizing the uncertainity in measurements. Because of that there are less chances for errors.Especially when it comes to medical devices safety is the priority for FDA so precision and accuracy is most important.Precision and Accuracy states that how close the instrument will work as per the standards. This is utmost important factors as wrong values would affect the diagnosis and would be hazardous for patients. As time goes by there are some differences in measurements of instrument so for this FDA has safety standards for calibration for maintenance of original standards. FDA might recall for drift in precision and accuracy.