Rq. Wharton et al., Venesection needle coring increases positive results with RT-PCR for detection of circulating cells expressing CEA mRNA, CLIN EXP M, 18(4), 2000, pp. 291-294
We assessed whether circulating cell positivity using RT-PCR for carcinoemb
ryonic antigen (CEA) cDNA was affected by venesection via a needle compared
/with a pre-aspirated venous cannula, and by increased PCR cycles. Systemic
blood was sampled by needle and pre-aspirated cannula in 101 healthy indiv
iduals with no cancer history. After erythrocyte removal, samples were subj
ected to RT-PCR using specific primers for CEA, with 29 or 35 RT-PCR cycles
. There was a significant difference between the number of subjects whose s
amples were negative when collected via needle venesection and positive whe
n collected via pre-aspirated cannula, compared with positive by needle ven
esection and negative by pre-aspirated cannula for both 29 (P=0.016) and 35
(P=0.011) RT-PCR cycles. Venesection technique (P=0.01) and number of cycl
es (P=0.003) were significant predictors of a positive result. Positive res
ults in healthy subjects were reduced to less than 3% when an aspirated can
nula was used for venesection and > 29 PCR cycles were avoided.