The usual approach for selection of samples would be to test instruments grouped into "families". For example, families could be determined as follows:

• Simple one piece instruments (e.g. dissecting forceps)
• Jointed instruments (e.g. needleholders)
• Complex instruments (e.g. cusco)
• Linen
• Laryngeal masks

One example from each family would be sent to the laboratory on a regular basis for bioburden testing post wash-disinfect but pre-sterilisation. The bioburden levels for each product should be consistent. This would prove that the cleaning process is in control and that routine sterilisation should be effective.