Table 3.

FNAB recommendations according to ultrasonography and clinical findings (American Thyroid Association)

USG and clinical findings	Nodule size recommended for FNAB	Strength of recommendation
High risk in history
Existent suspicious USG findings	>5 mm	Strongly recommended (A)
Nonexistent suspicious USG findings	>5 mm	Controversial (I)
Abnormal cervical lymph node	All nodules	Strongly recommended (A)
Microcalcification in nodule	≥1 cm	Recommended (B)
Solid nodule
Hypoechoic	>1 cm	Recommended (B)
Iso- or hyperechoic	≥1–1.5 cm	Recommended (C)
Mixed cystic-solid nodule
Existent suspicious USG findings	≥1.5–2 cm	Recommended (B)
Nonexistent suspicious USG findings	≥2 cm	Recommended (C)
Spongioform nodule	≥2 cm	Recommended (C)
Pure cystic nodule	No FNAB indication (unless it is for therapeutic purpose)	Not recommended (E)

FNAB: fine-needle aspiration biopsy; USG: ultrasonography