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 a Cold Thyroid Nodule in a Pregnant Woman at 14 Weeks

The next best option for a 33-year-old pregnant woman at 14 weeks with a painless thyroid mass identified as a cold nodule on scan is to perform fine-needle aspiration cytology (FNAC) and proceed with total thyroidectomy only if FNAC shows malignancy (option C). 1

Diagnostic Approach

• All thyroid nodules in pregnant women should be evaluated thoroughly, as up to 40% may be malignant 1
• Fine-needle aspiration cytology (FNAC) is the most reliable diagnostic tool for thyroid nodules during pregnancy and should be performed in any thyroid nodule >1 cm or in those <1 cm with suspicious features 1
• Ultrasound features that suggest malignancy include hypoechogenicity, microcalcifications, absence of peripheral halo, irregular borders, solid aspect, and intranodular blood flow 1
• A "cold" nodule on thyroid scan has higher risk of malignancy, though most cold nodules are still benign 1, 2

Management Algorithm

1. First step: Fine-needle aspiration cytology (FNAC)

   • FNAC has high sensitivity (80%) and specificity (97.7%) for diagnosing thyroid malignancy 2
   • FNAC is safe during pregnancy and standard diagnostic criteria can be used 3

2. If FNAC shows malignancy:

   • Proceed with total thyroidectomy preferably during the second trimester 1, 4
   • Second trimester is optimal for surgery as organogenesis is complete and risk of spontaneous abortion is lower than first trimester 4

3. If FNAC shows suspicious for follicular neoplasm:

   • Surgery can be deferred to the postpartum period 4
   • This is because most follicular neoplasms are benign adenomas 4

4. If FNAC shows benign cytology:

   • Observation is appropriate with no immediate intervention needed 4, 5

Important Considerations

• Thyroid cancer detected during pregnancy generally does not grow significantly or pose substantial risk during gestation 5
• Thyroid surgery in pregnant women carries higher risks than in non-pregnant women 5
• Radiation therapy (I-131) is absolutely contraindicated during pregnancy 1
• Thyroxine suppression therapy (option A) is not indicated as first-line treatment for a cold nodule without confirmed diagnosis 1
• Propylthiouracil (PTU) (option B) is only indicated for hyperthyroidism, not for cold nodules 1
• Hemithyroidectomy (option D) would be insufficient if malignancy is confirmed, as total thyroidectomy is the standard of care for thyroid cancer 1

Pitfalls to Avoid

• Do not proceed directly to surgery without FNAC confirmation of malignancy 4, 5
• Do not delay evaluation of thyroid nodules during pregnancy, as proper diagnosis guides management 1
• Do not use radioactive iodine for diagnostic or therapeutic purposes during pregnancy 1
• Do not assume all cold nodules are malignant; FNAC is essential for accurate diagnosis 2

By following this evidence-based approach, optimal outcomes can be achieved for both mother and fetus while appropriately managing the thyroid nodule.