Nondiagnostic Test Result Rates Following Thyroid Extra-Fine-Needle Aspiration

Area of Science:

• Endocrinology
• Pathology
• Surgical Oncology

Background:

• The Bethesda classification system categorizes thyroid fine-needle aspiration biopsy (FNAB) results.
• Nondiagnostic (ND) results, the first category, indicate inadequate cellularity for accurate evaluation.
• Needle diameter is a potential factor influencing FNAB specimen adequacy.

Purpose of the Study:

• To investigate the impact of different needle diameters (23-, 25-, and 27-gauge) on nondiagnostic (ND) rates in thyroid FNAB.
• To compare the diagnostic outcomes of FNAB samples obtained using varying needle sizes.

Main Methods:

• Retrospective analysis of 699 thyroid FNAB procedures performed between 2018 and 2021.
• Samples were collected using 23-gauge (n=144), 25-gauge (n=335), and 27-gauge (n=220) needles.
• Statistical analysis compared ND rates across different needle gauges and correlated nodule size with ND rates.

Main Results:

• Nondiagnostic (ND) rates were significantly higher with 27-gauge needles compared to 23- and 25-gauge needles (P=.002).
• A significantly lower ND rate was observed with 25-gauge needles versus 27-gauge needles (P=.001).
• Larger thyroid nodule size was associated with a reduced ND rate (OR, 0.801; 95% CI, 0.691-0.929).

Conclusions:

• 25-gauge needles are more effective than 27-gauge needles in minimizing nondiagnostic (ND) rates for thyroid nodule FNAB specimens.
• The findings suggest that needle gauge selection can impact specimen adequacy.
• Further prospective studies are recommended to validate these results.