Questions on Cleaning Validation Swab Area

The Question posed on LinkedIn: (seems to be a dead conversation now).

In a cleaning validation program, Which swab area is preferred ?

In any cleaning validation program, two common sample methods usually used.
One is rinse sampling and the other is swab sampling.
For swab sampling, some companies choose to use a 25 cm² swab area, others are using a 100 cm².
As per my limited info, no regulation ask to use a specific swab area.
But since you choose to use one of them, there must be a scientific rational/ justification, right ?

is it because, the larger is your swab area, the greater residues you can swab and recover ?

practically, some factors affect and effected by determining a swab surface area, Like ; recovery, the swabbed equipment part, residue limit..etc.

so, what is yours ?

My reply was this:

“Hi Ahmed.

This might help you in broad terms – the discussion is from 2005. Here there is a discussion of how a larger sample size does not lead to a larger recovery (past a certain point) so I’d want to see your recovery levels are validated and justification for your sample size. eg, xx cm squared gave the best recovery with xx brand swabs so that is why that was chosen for xx validation.

There is quite some emphasis placed on risk assessment these days so your validation should show how what you do represents the least amount of risk with regards to cleaning residues remaining on the sampled surfaces and how they might impact the product efficacy. So, best case recovery equals least risk to residues remaining.