Limitations of tests
Karyotype
Different sample types yield chromosome preparations with different G band resolutions, with blood samples giving the best resolution. An abnormality could, be detected in a blood sample but not in a prenatal or abortus sample from the same patient. Since the expected resolution varies between sample types, a case may be reported as substandard on a blood sample and still have been analysed at a higher resolution than a different sample type from the same patient. We aim to meet the minimum banding resolution recommended by National Professional standards. Where this has not been achieved this will be stated in the report.
Chromosome analysis cannot fully exclude mosaicism, or very small structural chromosome abnormalities. If mosaicism is suspected, the number of cells examined will be increased to improve the chances of detecting it.
Blood samples from parents or other family members (collected in lithium heparin tubes) or an additional sample from the same patient may occasionally be required to interpret the cytogenetic result. If required, these will be requested in the written report or, where the test is urgent, in discussions with the referring department.
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Page last updated 10/04/2024 by MC. Please note that if printed, the information is only valid on the day of printing.