[Blood transfusion audit methodology: the auditors, reference systems and audit guidelines].

The audit has become an essential aspect of the blood transfusion sector, and is a management tool that should be used judiciously. The main types of audit that can be envisaged in blood transfusion are the following: operational audit concerning a predetermined activity; systems quality audit; competence audit, combining the operational audit on a specific activity with quality management, e.g., laboratory accreditation; audit of the environmental management system; and social audit involving the organization of an activity and the management of human resources. However, the main type of audit considered in this article is the conformity audit, which in this context does not refer to internal control but to conformity with an internal guideline issued by the French National Blood Service. All audits are carried out on the basis of a predescribed method (contained in ISO 10 011). The audit is a system of investigation, evaluation and measurement, and also a means of continuous assessment and therefore improvement. The audit is based on set guidelines, but in fact consists of determining the difference between the directions given and what has actually been done. Auditing requires operational rigor and integrity, and has now become a profession in its own right.