"an isolated nodule in men < 35 years old"
"U3 nodule over 1 cm without cytology (FNAC not indicated or performed): Consider at least 2 years of ultrasound follow‐up before discharge."
"U3 nodule over 1 cm with Thy2 cytology results: Repeat FNAC is not mandated when a single Thy2 result is supported by two stable ultrasounds or the patient has two consecutive Thy2 results. Discharge is appropriate if the nodule is stable on repeat ultrasound at 12 months. Repeat FNAC is, however, recommended in the presence of ipsilateral lymphadenopathy, vocal cord palsy, interval growth or change in sonographic appearance. Local protocols should guide the need for repeat FNAC or follow‐up imaging."
"U3 nodule over 1 cm with two consecutive Thy1 cytology results: Recommend at least 2 years of ultrasound follow‐up or consider diagnostic hemithyroidectomy following shared decision‐making."
"In 2026, the BTA updated the guidelines and introduced a set of size criteria to aid the decision as to whether to perform FNA and a set of follow-up recommendations both for those nodules which have not been subjected to FNA and for those with indeterminate cytology. The recommendations also removed doppler assessment of intranodular vascularity from the 'U' system, but did not otherwise alter the sonographic evaluation criteria 3."
"In 2026, the BTA updated the guidelines and introduced a set of size criteria to aid the decision as to whether to perform FNA and a set of follow-up recommendations both for those nodules which have not been subjected to FNA and for those with indeterminate cytology. The recommendations also removed doppler assessment of intranodular vascularity from the 'U' system, but did not otherwise alter the sonographic evaluation criteria 3."
"taller than wide axially (AP>ML)"
"Nodules of any size do not require FNA in the absence of concerning clinical features (as detailed below)"
"1−2 cm: May undergo either FNAC or follow‐up ultrasound, according to local protocols"
"Over 2 cm: Should be considered for FNAC"
"5−10 mm: May be considered for FNAC or follow‐up ultrasound based on local MDT policy and concerning clinical or sonographic features"
"Over 1 cm: Should be considered for FNAC"
"U2 nodule over 1 cm with high‐risk clinical risk factors: Consideration of further follow‐up and/or FNA should be made on an individual basis, depending on clinical risk factors. High‐risk clinical features include, but are not limited to:"
"U3 nodule over 1 cm without cytology (FNAC not indicated or performed): Consider at least 2 years of ultrasound follow‐up before discharge."
"U3 nodule over 1 cm with Thy2 cytology results: Repeat FNAC is not mandated when a single Thy2 result is supported by two stable ultrasounds or the patient has two consecutive Thy2 results. Discharge is appropriate if the nodule is stable on repeat ultrasound at 12 months. Repeat FNAC is, however, recommended in the presence of ipsilateral lymphadenopathy, vocal cord palsy, interval growth or change in sonographic appearance. Local protocols should guide the need for repeat FNAC or follow‐up imaging."
"U3 nodule over 1 cm with Thy2 cytology results: Repeat FNAC is not mandated when a single Thy2 result is supported by two stable ultrasounds or the patient has two consecutive Thy2 results. Discharge is appropriate if the nodule is stable on repeat ultrasound at 12 months. Repeat FNAC is, however, recommended in the presence of ipsilateral lymphadenopathy, vocal cord palsy, interval growth or change in sonographic appearance. Local protocols should guide the need for repeat FNAC or follow‐up imaging."
"U3 nodule over 1 cm with Thy2 cytology results: Repeat FNAC is not mandated when a single Thy2 result is supported by two stable ultrasounds or the patient has two consecutive Thy2 results. Discharge is appropriate if the nodule is stable on repeat ultrasound at 12 months. Repeat FNAC is, however, recommended in the presence of ipsilateral lymphadenopathy, vocal cord palsy, interval growth or change in sonographic appearance. Local protocols should guide the need for repeat FNAC or follow‐up imaging."
"U4 or U5 nodule under 1 cm without cytology (FNAC not indicated or performed): Recommend at least 2 years of ultrasound follow‐up before considering discharge"
"American College of Radiology: ACR TI-RADS"
"American College of Radiology: ACR TI-RADS"
"European Thyroid Association: EU-TIRADS"
"Korean Society of Thyroid Radiology: K-TIRADS"
"SRU guidelines for assessment of thyroid nodules"
"ATA guidelines for assessment of thyroid nodules"
"solid homogenous markedly hyperechoic nodule with halo (follicular lesions)"
"Nodules of any size do not require FNA in the absence of concerning clinical features (as detailed below)"
"Under 1 cm: May be discharged if asymptomatic and without suspicious clinical features. Follow‐up ultrasound should be reserved for cases with significant clinical suspicion"
"Over 2 cm: Should be considered for FNAC"
"Over 1 cm: Should be considered for FNAC"
"Patients with benign (U2) thyroid nodules which do not cause compressive symptoms and do not require thermal ablation or surgery may be discharged without further follow‐up"
"The frequency and duration of follow‐up should be tailored based on ultrasonographic and/or cytological features of the nodule"
"Development of new symptoms or lymphadenopathy"
"Underlying clinical risk factors"
"Evidence of progression or growth on follow‐up imaging"
"The underlying health status of the patient and comorbidities"
"American College of Radiology: ACR TI-RADS"
"European Thyroid Association: EU-TIRADS"
"Korean Society of Thyroid Radiology: K-TIRADS"
"Under 1 cm: May be discharged if asymptomatic and without suspicious clinical features. Follow‐up ultrasound should be reserved for cases with significant clinical suspicion"
"1−2 cm: May undergo either FNAC or follow‐up ultrasound, according to local protocols"
"Over 2 cm: Should be considered for FNAC"
"5−10 mm: May be considered for FNAC or follow‐up ultrasound based on local MDT policy and concerning clinical or sonographic features"
"Over 1 cm: Should be considered for FNAC"
"U2 nodule over 1 cm with high‐risk clinical risk factors: Consideration of further follow‐up and/or FNA should be made on an individual basis, depending on clinical risk factors. High‐risk clinical features include, but are not limited to:"
"U3 nodule over 1 cm with two consecutive Thy1 cytology results: Recommend at least 2 years of ultrasound follow‐up or consider diagnostic hemithyroidectomy following shared decision‐making."
"Thy3a, Thy3f, Thy4 or Thy5 cytology managed conservatively: Most of these nodules will undergo diagnostic or therapeutic surgery. If surgery is not performed, a minimum of 5 years of follow‐up is recommended, with annual ultrasound surveillance"
"If follow‐up is recommended for benign or low‐risk nodules, a repeat ultrasound should be performed at 12 months. Earlier scanning is not considered beneficial, given that most benign and malignant nodules remain stable during conservative management"
"U4/U5"
Expected headings
"U1 (normal)"
"U2 (benign)"
"U3 (indeterminate)"
"U4 (suspicious)"
"U5 (malignant)"
"Size criteria"
"Follow-up recommendations"
"General recommendations"
"Suggested follow‐up strategies by nodule type"
"U2"
"U3"
"U4/U5"
"Malignant or indeterminate cytology managed conservatively"
"This classification system allows for the stratification of thyroid nodules as benign, suspicious or malignant based on ultrasound appearances termed U1-U5 to aid further investigation and management."
"Thy3a, Thy3f, Thy4 or Thy5 cytology managed conservatively: Most of these nodules will undergo diagnostic or therapeutic surgery. If surgery is not performed, a minimum of 5 years of follow‐up is recommended, with annual ultrasound surveillance"