The Impact of Ultrasound-Guided Fine-Needle Aspiration Cytology in the Management of Thyroid Nodule

Abstract

Fine-needle aspiration cytology (FNAC) is the gold standard for evaluating thyroid nodules, which groups thyroid nodules into six categories based on The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). Further management will depend upon the category. Ultrasound-guided fine needle aspiration cytology (USG-FNAC) has revolutionized the sample yield in FNAC. The palpatory method is being used in many developing countries due to the non-availability of suitable ultrasound resources and trained radiologists or surgeons. This paper intends to compare both methods of FNACs with respect to sample yield. This was a 456-patient mixed cohort analysis that included prospectively collected data from 256 patients with USG-FNAC, over 1 year, compared with a historical control of 200 patients who had palpation-guided FNAC(P-FNAC). The influence of the method of FNAC on TBSRTC classification and changes in the surgical intervention were studied. Univariate and multivariate analyses were performed to predict the factors that influenced the adequacy of FNAC. The mean age of the study population was 42.6 ± 12.7 years and 75% were women. FNAC was inadequate in 17.5% of the USG-FNAC group and 24.6% of P-FNAC, after excluding cystic nodules. Performing USG-FNAC increased the adequacy of FNA by 7.2% (p = 0.046) and increased the chance of detecting benign nodules by 17.3% (p < 0.001) compared to the palpation method. There was a reduction in the number of surgeries performed in the USG-FNAC group by 10.9% (p = 0.01). On multivariate analysis, USG-FNAC was associated with decreased sample inadequacy (OR 0.23; 95% CI 0.09-0.59; p < 0.002), presence of cystic component (OR 11.20; 95% CI 1.74-72.04; p = 0.011), or solid-cystic component in the tumor in USG (OR 2.82; 95% CI 1.04-7.62; p = 0.041) and had a negative impact on adequacy of the FNAC sample. USG-FNAC-guided procedures not only helped in improving sample adequacy, but also improved benign categorisation of thyroid nodules. It eventually reduced the number of unnecessary surgical procedures performed. Consistency of the nodule had a significant impact on FNAC adequacy.

Supplementary information: The online version contains supplementary material available at 10.1007/s13193-024-02158-8.

Keywords: Cytodiagnosis; Image-guided biopsy; Interventional; Thyroid nodule; Ultrasonography.