SRU guidelines for assessment of thyroid nodules

Last revised by Henry Knipe on 20 May 2020

The Society of Radiologists in Ultrasound (SRU) guidelines for the assessment of thyroid nodules were defined in a consensus conference statement published in 2005 focused on which thyroid nodules detected on ultrasonography should undergo fine needle aspiration.


The recommendations apply to thyroid nodules ≥1 cm in maximal diameter, evaluated by ultrasonography, in adult patients without a history of thyroid cancer 1. The language of the recommendations leave room for physician discretion based on the individual patient scenario. The biopsy technique of choice is ultrasound-guided fine needle aspiration. 

Solitary nodule

The risk of malignancy, and therefore management recommendation, depends on the presence of the following sonographic features and size thresholds:

  • microcalcifications: strongly consider biopsy if ≥1 cm
  • coarse calcifications: strongly consider biopsy if ≥1.5 cm
  • solid or mainly solid: strongly consider biopsy if ≥1.5 cm
  • mixed solid and cystic or mainly cystic with solid mural component: consider biopsy if ≥2.0 cm
  • substantial growth since prior ultrasound: consider biopsy
  • almost entirely cystic with none of the above features: biopsy probably unnecessary
Multiple nodules
  • multiple nodules: consider biopsy of one or more nodules prioritized by the criteria for solitary nodules in the order listed above
  • diffusely enlarged gland with multiple similar-appearing nodules without intervening parenchyma: biopsy is likely unnecessary
  • presence of abnormal lymph nodes: biopsy lymph node and/or ipsilateral nodule (this finding overrides thyroid nodule features)
Nondiagnostic biopsy

If the initial fine needle aspiration is nondiagnostic, a repeat fine needle aspiration should be considered for nodules meeting the original criteria above.

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