What is the next best option for a 33-year-old pregnant woman at 14 weeks gestation with a painless thyroid mass identified as a cold nodule on scan?

Management of Cold Thyroid Nodule in Pregnancy

The next best option for a 33-year-old pregnant woman at 14 weeks gestation with a painless thyroid mass identified as a cold nodule on scan is to perform a fine-needle aspiration biopsy (FNAB) before considering any treatment option. 1

Diagnostic Approach

1. Fine-needle aspiration biopsy (FNAB) is mandatory first step

   • FNAB is the most accurate technique for assessing malignancy potential 2
   • Can be safely performed during pregnancy 1, 3
   • Accuracy of cytologic diagnosis approaches 95% 4
   • Should be ultrasound-guided for optimal results 5

2. Management based on FNAB results:

   • If FNAB shows benign cytology:

     • Observation is appropriate during pregnancy
     • No immediate intervention needed 1

   • If FNAB shows malignancy/highly suspicious for papillary cancer:

     • Surgery during second trimester (lowest risk period)
     • Hemithyroidectomy for localized disease
     • Total thyroidectomy only for extensive disease 1

   • If FNAB shows follicular neoplasm:

     • Surgery can be deferred to postpartum period 1

Why the listed options are not appropriate without FNAB:

• Thyroxine oral (Option A):

  • Not indicated for management of thyroid nodules without confirmed diagnosis
  • Only used for hypothyroidism, which has not been established in this case 1

• PTU (Option B):

  • Only used for hyperthyroidism, not for management of thyroid nodules
  • No indication of hyperthyroidism in this patient 1

• Total Thyroidectomy (Option C):

  • Extremely aggressive without cytologic confirmation of malignancy
  • Carries higher risks during pregnancy 1

• Hemi thyroidectomy (Option D):

  • Only appropriate if FNAB confirms malignancy
  • Should be performed in second trimester if necessary 1

Important Considerations

• Cold nodules have higher malignancy risk than other nodules (34.6% for solid cold nodules) but still majority are benign 1
• Rushing to treatment without diagnosis is not recommended 1
• Unnecessary surgery during pregnancy should be avoided 1
• Most thyroid cancers discovered during pregnancy are differentiated thyroid cancers with excellent prognosis 1
• No characteristic cytologic features ascribable to pregnancy have been identified in thyroid nodules 3

Clinical Pearls

• Ultrasound characteristics should be evaluated to determine risk of malignancy (size, microcalcifications, hypoechogenicity, irregular borders, solid composition) 1
• For optimal FNAB results, 2-4 aspirations should be attempted from different areas of the nodule 2
• Molecular testing for somatic mutations (e.g., BRAF) can improve diagnostic accuracy in indeterminate cases 6
• Second trimester is optimal for thyroid surgery if required 1