The foetus is technically a "deep compartment". In other words, it takes a little longer for anaesthetic drugs to reach effective concentrations in the foetal brain than in the woman's. However, they do diffuse across the placenta and will reach equilibrium. Leaving aside the question of whether there is anything in a foetus's head that can experience pain in a meaningful sense at 10-12 weeks, the nerves involved are in no condition to do so while the woman is anaesthetised.
Abortion is not a decision lightly reached or an operation lightly carried out, but to dwell on legendary (that is, half historical and half imaginary) horrors neither advances the argument nor lends credibility to the moral stance of absolutists against abortion.
As for a time-expired frozen embryo, there is too much fuss about something with fewer cells than an ant, and no neurones at all.
A K MIDGLEY
GP, lately anaesthetic registrar