Important Role of Ultrasonography Immediately After Fine-Needle Aspiration Biopsy of Thyroid Nodules to Detect Acute Transient Thyroid Swelling.

OBJECTIVE

We aimed to determine whether early detection of acute transient thyroid swelling (ATTS) is possible using ultrasonography (US) surveillance immediately after fine-needle aspiration biopsy (FNAB) and discuss the usefulness of routine US after FNAB.

METHODS

We retrospectively evaluated the incidence, clinical features, and US and computed tomography findings of ATTS in patients with thyroid nodules who underwent FNABs at our hospital. The study period was divided into two time periods: only symptomatic patients after FNAB were examined using US in the first period (period A: January 2016 to November 2020), whereas all patients were routinely examined using US shortly after FNAB in the second period (period B: December 2020 to December 2022).

RESULTS

We found that the frequency of ATTS increased from 0.18% (10/5,685) in period A to 1.58% (31/1,958) in period B because the majority of ATTS cases in period B were asymptomatic. Follow-up US performed 15 minutes to 3 hours later confirmed no exacerbation of thyroid swelling in patients diagnosed with ATTS during period B. Routine US examinations, shortly after FNAB, significantly reduced the number of return visits after discharge (from 5/10 to 2/31, p=0.006). Furthermore, the incidence of unilateral swelling was higher than previously reported.

CONCLUSION

Routine US examinations shortly after FNAB may be useful in identifying ATTS regardless of the presence of symptoms; moreover, they may reduce patients' return visits after leaving the hospital. It is also important to inform patients that delayed complications are possible and that severe cases, although rare, do exist.