His doctor sent him to do an IVP - an X-Ray using dye material to make sure his kidney is functioning fine. The kidney looks fine on picture but the gallbladder shown some shadows. So the doctor sent him to do an ultrasound for the gallbladder - the outcome is there is a good size stone! So the primary doctor scheduled him to see a surgeon.
Because he has not felt anything at all, such is called "silent stone" - usually discovered by accident.
Since our trip is a long one and out of the country, we would prefer to have it done before hand.
It is not an invasive operation from what I googled - usually an overnight stay at hospital and about a week restricted movement afterward.