can u still have stones even though scan didnt show them up?

i had a scan today didnt show up Gallstones i did test through genova a comprehensive stool tests which tests for everything including candida to Gallstones it showed up that i had obstruction in my gallbladder but no candida the nutropth said she def thinks i have Gallstones because of this could u still have gallstones even if they dont show up on scan??