The rates of inadequate material for palpation-guided FNAB (32.3%) and ultrasound-guided FNAB (21.4%) were significantly different, (p=0.004).
The nodules were divided arbitrarily into two groups. There were 157 (55.1%) small-sized nodules (10 - 15 mm) and 128 (44.9%) large-sized nodules (16 - 25 mm).
With palpation-guided FNAB, the rate of inadequate material was 59 (37.6%) for the small-sized group and 33 (25.8%) for the large-sized group, (p=0.03).
With ultrasound-guided FNAB, the rate of inadequate material was 38 (24.2%) for the small-sized group and 23 (18%) for the large-sized group, (p=0.02).
Comparing small- and large-sized groups with palpation-guided FNAB and ultrasound-guided FNAB revealed a statistically significant difference in small nodules only (37.6% versus 24.2%, p=0.009).
There was no statistically significant difference in large nodules (25.8% versus 18.0%, p=0.154).
In the sub-group of 26 nodules that underwent histology, the results for palpation-guided FNAB versus ultrasound-guided FNAB were as follows:
sensitivity, 57.1% versus 85.7%;
specificity, 84.2% versus 89.5%;
PPV, 57.1% versus 75%;
NPV, 84.2% versus 94.4%;
accuracy, 76.9% versus FNAB 88.5%;
false positives, 33.3% versus 25%; and
false negatives, 15.8% versus 5.6%.
No statistical analysis of these findings was performed.