Why is that microdeletions and microinsertions difficult to diagnosis using karotypes

Answer
             Karyotype is related to determine the size, shape and number of chromosomes in a single species of an organism.
Micro deletion is related to the deletion of any part of DNA in an organism, whereas microinsertion is the addition of extra DNA part in a particuar chromosomes.
In order to diagnose such abnormalities molecular level diagnosis should be studied using fluorescence in situ hybridization, irrespective of high-resolution chromosome results (Karyotyping).