What is the next best step 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 Thyroid Nodule in a Pregnant Woman

Fine needle aspiration cytology (FNAC) is the next best option for a 33-year-old pregnant woman at 14 weeks gestation with a painless thyroid cold nodule. 1

Diagnostic Approach for Cold Thyroid Nodules in Pregnancy

Cold nodules have a higher risk of malignancy (approximately 20-30% in solid cold nodules) and require proper evaluation to rule out cancer. The management approach should be systematic:

1. FNAC is the critical first step to determine if the nodule is benign or malignant

   • Can be safely performed during pregnancy with high sensitivity for malignancy detection 1
   • Should be performed for any thyroid nodule >1 cm or smaller nodules with suspicious features 2
   • Provides reliable cytological diagnosis to guide further management

2. Ultrasound characteristics should be carefully evaluated for suspicious features:

   • Hypoechogenicity
   • Microcalcifications
   • Irregular borders
   • Absence of peripheral halo
   • Solid composition 1

Management Based on FNAC Results

If FNAC shows malignancy (Option C):

• Total thyroidectomy during the second trimester is recommended for confirmed malignancy 1, 3
• Second trimester carries the lowest risk for surgical intervention during pregnancy
• Allows for complete removal of cancer and facilitates follow-up treatment

If FNAC shows BIRAD IV/suspicious findings (Option D):

• Hemithyroidectomy may be appropriate for well-differentiated thyroid cancers confined to one lobe 1
• However, total thyroidectomy would be preferred for more extensive disease
• The concordance rate between suspicious cytology and final histological diagnosis varies:
  • 100% for definitive papillary cancer
  • 50% for findings suspicious for papillary cancer 3

If FNAC shows benign findings:

• Clinical follow-up with repeat ultrasound is recommended
• Surgery can be safely delayed until after delivery 1

Why Other Options Are Not Appropriate

• Thyroxine oral (Option A): Not indicated for cold nodules without confirmed benign status and hypothyroidism. Recent reports cast doubt on the efficacy of suppressive therapy for thyroid nodules 1, 4

• PTU (Option B): Only indicated for hyperthyroidism, not for cold nodules which are typically not hyperfunctioning 1

Common Pitfalls to Avoid

• Delaying diagnosis of a suspicious nodule
• Assuming benign nature without cytologic evaluation
• Starting medication therapy without clear indication based on thyroid function tests
• Performing surgery without cytological confirmation of malignancy 1

Follow-Up Considerations

• For nodules with benign cytology, clinical follow-up with repeat ultrasound is appropriate
• Non-diagnostic FNA results require repeat FNA, possibly ultrasound-guided
• If surgery is delayed until after delivery, close monitoring throughout pregnancy is essential 1

The high concordance rate between cytological findings and final histological diagnosis (100% for benign and malignant lesions) supports FNAC as the most appropriate next step to guide further management decisions 3.