These three tests look at your chromosomes at different levels of detail, and geneticists often use them together rather than picking just one:

*Karyotype- a whole-genome overview. It shows the number and general structure of all 46 chromosomes and can catch large-scale changes (extra/missing chromosomes, big deletions or rearrangements), but it can’t see very small changes.
*Fluorescence In Situ Hybridization- a targeted test. A fluorescent probe is designed to bind to one specific region of interest, giving a fast, precise yes/no answer about that particular spot, but it only checks the region(s) you test for, not the whole genome. The results turn around time is faster compared to karyotyping.
*Chromosomal Microarray (CMA)- a genome-wide scan for small gains or losses of genetic material, at a resolution far beyond standard karyotyping, though it generally can’t detect balanced rearrangements (where material is rearranged but nothing is gained or lost).