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Limitations of tests


Different sample types yield chromosome preparations with different G band resolutions, blood samples in general give the best resolution. An abnormality could, therefore, be detected in a blood sample which was not apparent in a prenatal sample or abortus material 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 analyse samples to meet the minimum banding resolution recommended by National Professional standards. Where this has not been achieved this will be stated in our reports.

Chromosome analysis cannot guarantee to exclude the presence of 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 specimen from the same patient may occasionally be required in order to interpret the cytogenetic result. If required, these will be requested either in the written report or, where the test is urgent, in discussions with the referring department.

Please click below for sample specific limitations

Page last updated 22/02/2021 by MC. Please note that if printed, the information is only valid on the day of printing.