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 Pregnancy

Fine-needle aspiration biopsy (FNAB) 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. 1

Diagnostic Approach for Thyroid Nodules in Pregnancy

The management of thyroid nodules during pregnancy should follow a systematic approach similar to non-pregnant patients, with special considerations for the gestational state:

1. Initial Evaluation: A cold nodule on scan requires further evaluation to determine if it is benign or malignant before any treatment decisions are made 1

2. FNAB as First-Line Diagnostic Tool:

   • FNAB has replaced imaging studies as the routine initial procedure for differentiating benign from malignant nodules 2
   • It provides reliable and cost-effective cytologic diagnosis with high concordance rates 3
   • Should be performed in any thyroid nodule >1 cm or in smaller nodules with suspicious features 4

3. Timing of FNAB:

   • For patients who present before 20 weeks of gestation (as in this case), FNAB should be performed, especially with:
     • Solid nodules larger than 2 cm
     • Rapidly enlarging nodules
     • Nodules associated with cervical lymphadenopathy 5

Why Other Options Are Not Appropriate

• Thyroxine oral (Option A): Not indicated without first determining if the nodule is benign or malignant. Recent reports cast doubt on the efficacy of suppressive therapy for benign nodules 2, and it should not be used without clear indication based on thyroid function tests 1

• PTU (Option B): Propylthiouracil is used for treating hyperthyroidism, not for managing cold nodules. There is no indication of hyperthyroidism in this case 1

• Total Thyroidectomy (Option C): Surgery without cytologic diagnosis is inappropriate. If surgery becomes necessary, it should be performed during the second trimester for confirmed malignancy 1, 3

• Hemithyroidectomy (Option D): Like total thyroidectomy, this surgical approach should only be considered after FNAB confirms or strongly suggests malignancy 1

Management Algorithm Based on FNAB Results

1. If FNAB shows benign cytology:

   • Observation is appropriate during pregnancy
   • High concordance rate (100%) between benign cytology and final histological diagnosis 3

2. If FNAB shows malignancy or is highly suspicious for papillary cancer:

   • Surgery (hemithyroidectomy or total thyroidectomy depending on extent) during the second trimester 3
   • The second trimester carries the lowest risk for surgical intervention during pregnancy 1

3. If FNAB shows follicular neoplasm:

   • Surgery can be deferred to the postpartum period 3

Important Considerations

• The incidence of malignancy in solid cold nodules has been reported to be around 34.6% 6, highlighting the importance of proper evaluation
• Proper risk stratification can avoid unnecessary procedures during pregnancy 1
• Radionuclide scanning should not be repeated during pregnancy due to radiation concerns 1
• Ultrasound can provide additional information about nodule characteristics if needed 1

Remember that rushing to treatment without proper diagnosis is not recommended, and the primary goal is to identify potential malignancy while minimizing risk to both mother and fetus.