What is the next best management option for a 14-week pregnant woman with a painless thyroid mass diagnosed as a cold nodule on scan?

Management of Cold Thyroid Nodule in Pregnancy

The next best option for a 14-week pregnant woman with a painless thyroid mass diagnosed as a cold nodule on scan is to perform a fine-needle aspiration biopsy (FNAB) first, followed by hemithyroidectomy during the second trimester if malignancy is confirmed or highly suspected.

Diagnostic Approach

Before deciding on any treatment option, proper diagnosis is essential:

1. Fine-needle aspiration biopsy (FNAB) is the critical first step:

   • FNAB should be performed for all thyroid nodules >1 cm or smaller nodules with suspicious features 1
   • FNAB has high concordance rates with final histological diagnosis 2
   • FNAB is safe during pregnancy and should be performed especially before 20 weeks gestation 1

2. Ultrasound characteristics to evaluate:

   • Hypoechogenicity, microcalcifications, absence of peripheral halo, irregular borders, solid aspect, and intranodular blood flow suggest malignancy 3
   • ACR TI-RADS risk stratification system helps guide management 1

Management Algorithm Based on FNAB Results

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

• Hemithyroidectomy during the second trimester is recommended 1, 2
• This timing carries the lowest risk for surgical intervention during pregnancy
• For well-differentiated thyroid cancers confined to one lobe, hemithyroidectomy may be appropriate 1

If FNAB shows follicular neoplasm:

• Surgery can be safely deferred to the postpartum period 1, 2
• All 3 nodules with cytological findings suspicious for follicular neoplasm were benign adenomas histologically in one study 2

If FNAB shows benign cytology:

• Observation is appropriate during pregnancy 1
• High concordance rate (100%) between benign cytology and final histological diagnosis 2

Why Total Thyroidectomy is Not First-Line

Total thyroidectomy (option C) would be excessive without first confirming malignancy through FNAB. According to guidelines:

• Total thyroidectomy would only be considered for more extensive disease after diagnosis 1
• Unnecessary surgery during pregnancy should be avoided 1
• The American College of Radiology emphasizes not rushing to treatment without proper diagnosis 1

Why Medication Options Are Not Appropriate

• Thyroxine (option A) is not indicated for cold nodules without confirmation of thyroid function status 1
• PTU (option B) is only used for hyperthyroidism, not for management of thyroid nodules 3, 1

Timing of Surgery if Needed

• Second trimester is optimal for thyroid surgery if required 1, 2
• For nodules discovered later in pregnancy, work-up and treatment can be safely delayed until after delivery 4

Important Considerations

• Most thyroid cancers discovered during pregnancy are differentiated thyroid cancers with excellent prognosis 4
• Thyroid cancer during pregnancy rarely grows rapidly or poses significant risk during gestation 5
• Thyroid surgery in pregnant women carries higher risks than in non-pregnant women 5

Between options C (Total Thyroidectomy) and D (Hemithyroidectomy), hemithyroidectomy would be more appropriate if surgery is needed after FNAB confirms malignancy, as it is less invasive while still addressing the nodule, especially for well-differentiated thyroid cancers confined to one lobe.