Factors affecting inadequate sampling of ultrasound-guided fine-needle aspiration biopsy of thyroid nodules.

PURPOSE

The aim of this study was to evaluate the overall ultrasonographic features and clinical factors that contribute to inadequate sampling in ultrasound-guided fine-needle aspiration biopsy (US-FNAB) of thyroid nodules.

MATERIALS AND METHODS

From April 2008 to December 2008, 4077 US-FNABs in 3767 consecutive patients were reviewed. We evaluated the clinical, ultrasound and pathological features of patients and analysed the association between these features and inadequate samples. We also compared inadequate sample rates according to the experience of the performing doctor.

RESULTS

The inadequate sample rate was 16·1% (654/4077). Univariate analysis revealed an association between inadequate samples and cyst dominancy, macrocalcification and benign pathology of the nodule. The inadequate sample rate was also higher in the inexperienced group than in the experienced group. In multivariate analysis, cyst dominancy and macrocalcification of a nodule were significantly associated with inadequate samples in the experienced group.

CONCLUSION

Cyst dominancy and macrocalcifications in thyroid nodules, inexperience of the performing doctor and benign pathology were factors associated with high inadequate sample rates of US-FNAB in thyroid nodules.