Yorkiemom,
I've had Hashimoto's thyroiditis for ~12yrs now and for the 1st 6yrs I had fine needle aspiration biopsies of my ever enlarging thyroid done every 6mos. The doc was an endocrinologist who did them in his office w/out a local. He was very skilled and took 4-6 aspirations each time. All I ever felt was a little pin prick. The bloody thryoid exam where here squeezed my throat while swallowing was much more unpleasant to me. Kept telling me that this was worse for him but he never gave me the chance to give him an exam either!
Since I have PN too I can echo Dahlek's comments that there is no comparison between the pains. The biopsy pain was brief and minimal by comparison.
By all means if a little anesthetic will take the edge off for you, go for it, but the 12 procedures I had were not that bad.
Hope all goes well for you and that the results will be good ones.
Alkymst