Success rate of repeated fine needle aspiration biopsy of clinically suspicious thyroid nodules

In this study we evaluated the success rate of double fine needle aspiration biopsy (FNAB) of clinically suspicious thyroid nodules in one session.

The success rate of FNAB in clinical setting is quite low. There were several attempts made to improve the success rate of this method. It is anticipated that a double FNAB in one session would increase the success rate of FNAB.

176 consecutive patients (130 women, 46 men; mean age 56 years ± 11) with at least one clinically suspicious nodule were included in this study. Each individual nodule was biopsied twice (20G- and 21G-needle). In 33 patients, two suspicious nodules were biopsied, accounting for a total of 209 biopsied thyroid nodules. To evaluate the success rate the number of cell formations and the total number of cells in each cell formation were counted.

The biopsy with the 20G needle provided in mean 40 cell cluster with a mean of 830 cells whereas the 21G needle provided in mean 41 cell cluster with a mean of 1010 cells. With the 20G needle the success rate was 73%, with the 21G needle 78% and the combination of the both biopsies provided a success rate of 87% (p = 0.01). Based on the number of cell formations and the total number of cells, the difference between the two needle sizes was not significant (p = 0.5 for cell formations and p = 0.9 for the total number of cells, respectively).

A double FNAB of suspicious thyroid nodules in one session provides a higher success rate, and a 21G needle is sufficient enough.