The National Breast Implant Registry comprises a prospective registry and a retrospective registry. It covers both the private and the National Health sectors. The Medical Devices Agency funds the registry and owns the data but has no direct access to confidential information such as patient names.

 In the UK, there is no legislative basis for compulsory implant registries and the prospective and retrospective registries are therefore voluntary; reporting by clinicians is an aspect of good professional practice rather than a legal requirement. A consequence of voluntary registration is that entry of data onto the registry is dependent upon consent being given by the patient. Individual patients may refuse to be registered, but those that allow the information to be included have agreed to the use of their data in future analyses. The reporting centres supply details of the patient, implant and operation to the prospective registry. The name and any other classifying information on the surgeon performing the implantation is not currently collected. Registrations on the retrospective registry may come from any source, including patients. In both cases information is held on a database and is subject to the Data Protection Act.

 Initially, hospitals with an operating theatre department were identified and the Registry wrote to individual plastic surgeons. This approach continues with the identification of centres that are not reporting either by geographical targeting or by other information, such as surgeons from new centres requesting forms. There are around 280 centres reporting to the Registry in varying numbers each year. These cover a large proportion of the centres undertaking breast implantation in the UK, although around 80% of the work is done in about 30 centres. There are good relations between the Registry and the surgeons, administrators, theatre managers and nurses who supply information to it.

 The Registry collects demographic details about patients, identification of the type of implant, the anatomical location of the implant and the indications for the operation. The main registration form for the prospective register is designed to be used for implantation and/or explantation. However, based on the numbers received, the Registry may not be receiving notification of all explantations carried out. A number of reasons may explain this such as the incident being remote from the registration of the original implant or those involved being unaware that this is a registerable event. About 3% of the registrations are associated with repeat procedures of some sort.

 There is a potential problem with voluntary registration in that the denominator (the actual total number of implants) remains unknown. Furthermore, if there is any selection bias inherent in registration, then interpretation of the data that emerge, on complications (either local or of long-term health consequences) could be compromised. There are a number of limitations preventing simple measurement of the registration rate. Manufacturers' sales figures do not provide an accurate measure of compliance since most hospitals keep a stock of implants on a "sale or return" basis rather than ordering and using implants for individual patients. The recording of information within individual reporting centres may not allow identification of all breast implant recipients. In the Registry's own centre, compliance has been measured at about 90%. This has also been checked in studies involving another two collaborating units and the estimate from these exercises is in excess of 65% to 70% of the implant procedures are being recorded. This is believed to be a representative sample of procedures being carried out in this country.

 Details of the retrospective registry were circulated to interested patient groups and there were initially a number of retrospective implant registrations. These registrations have now decreased markedly, and registration rates were not affected by recent publicity about US litigation.

 The National Breast Implant Registry produces annual reports of its activities and in addition provides quarterly reports to reporting centres on their registration activities.