True, Primary Hyperparathyroidism in itself is relatively rare 1 in 1,000 per head of population, yet the incidence of more than one tumour in that population is about 4 - 6%. The problem lies in the fact that in those 4 - 6% with more than one tumour - the radioactivity of the sestamibi tends to pool in the larger tumour and the smaller tumour does not 'show up'. Patients with more than one tumour often feel some benefit from having the larger one removed, but as the smaller one grows, they end up ill again. The focused surgery works for most, but not those unfortunate 4 - 6 %. In the practice of a skilled and experienced surgeon such as Dr. Norman, there is little difference in incision size, operating time, recovery and complications between 'focused' and a full exploration of all 4 glands, and so it makes sense for both surgeon and patient to have all 4 glands inspected whilst under the knife.
I would argue that the decision to go focused or full exploration would be a different matter if you were seeing an inexperienced surgeon who's focused surgery is something like a 2-3 inch scar and whose 'full exploration' is a 5 - 6inch scar with a week in hospital to recover. In that case I would probably go for the focused surgery and 'hope' I wasn't one of the unlucky 4 - 6 % who had more than one tumour. There are unfortunately, plenty of local NHS surgeons out there who do a 5 - 6 inch scar for a full exploration. This is one of the reasons I looked outside of my local PCT for parathyroid surgery.