But if they are going to go with the blanket invite approach, they should probably record someone's inferred-sex-at-birth rather than just their current gender.*
Well if they're currently using the gender someone has ticked on a from to determine which letters they send then the NHS clearly doesn't have this information to hand at the moment.
So to do this, presumably, they'd have to re-design^^ and re-distribute the form they currently use so it also asks for sex-at-birth as well as current gender? This would presumable have to be back-dated so basically everyone in the U.K. would need to be sent the form, and complete and return it.
Then re-design the database so this data can be stored. Then this data would have to be added to the database somehow.
Then there would have to be developments made to the output from the database - so the new 'sex-at-birth' fields are used for the letter generation instead.
Then the accompanying leaflets would have to be re-designed and re-printed.
Then there's the cost of training for those maintaining the database, making staff in GPs aware of the changes and the impact etc.
When realistically how many people are we talking about here? - Even if someone identifies as male but they know they have a cervix the chances are they'll know they should get a cervical cancer screening. And if they don't they'll probably see a doctor/nurse at some point about something and it could be mentioned to them then. And even if they don't, what are the odds of them getting cancer?
The costs of the cancer treatment for the few who do slip thorough will be minuscule compared to the costs of changing the NHS databases. It's a numbers game.
The same applies to the statistics of those not attending. Compared to the millions of people in the UK the number of people not attending because they have been sent a letter inviting them to make an appointment for a smear test, but they don't have a cervix, will be so small it will be negligible.
A better approach would be to run awareness campaigns to remind people that whatever gender they identify as being if they have a cervix - get it checked, if they have a prostate - get it checked etc. But even that costs money that the NHS doesn't have!!!