Novel data on needle technique at EBUS TBNA shows as few as 3 agitations of the needle is enough for adequate DNA on smears along with avoiding erythrocyte contamination of the smears.
D. Fielding*a (Dr), A. Dalleyb (Dr), P. Simpsonb (Dr), K. Nonesc (Dr), V. Lakisc (Dr), S. Sharmac (Dr)
a RBWH, Brisbane, AUSTRALIA ; b University of Queensland Centre for Clinical Research, Brisbane, AUSTRALIA ; c Queensland Institute for Medical Research Berghofer, Brisbane, AUSTRALIA
Optimising the EBUS TBNA needling technique is important to maintain procedural simplicity and maximise sample quality. The number of agitations of the needle within the lymph node has not been studied for lung cancer, nor has which component of the content is placed on the smear- the first or the last drops out of the needle. Fewer agitations might mean less trauma to the node, but it would be important to confirm adequate DNA was available.
We prospectively explored three versus 10 agitations of the needle in sequential passes into the lymph node using separate needles in EBUS TBNA for malignant nodes. Resulting Diff-Quik cytology smears were quantitatively assessed using microscopic (tumour cell cellularity, abundance scores, erythrocyte contamination) and DNA yields.
In 86 patients (45M, 41F), a mean of 5.3 smears were made per patient with a total of 459 smears scored by pathologists, and 168 paired smears extracted for DNA. There was significantly less contamination by erythrocytes from three agitations (X2 p=0.008) as judged by microscopy. There was no significant difference between three versus 10 agitations for smear microscopy cellularity (p= 0.29) however there was significantly higher cellularity in smears made from the last drops out of the needle compared to the first drops (p= 0.01) . Overall there was no difference in DNA yield (469ng vs 488 ng, P=0.84) or DNA integrity (p=0.20). However there was significantly more DNA in the first pass into the node using three agitations than with other passes and with 10 agitations (Pass * Agitations interaction, p=0.031).
Three agitations is non-inferior to 10 agitations for overall abundance of malignant cells and DNA content on smears. A smear with adequate DNA for panel sequencing could almost always be made with the first needle pass using three agitations.
Disclosure of funding source(s):
Cancer Council Queensland