Optimal Timing for a Repeat FNA Biopsy of Thyroid Nodule Following an Initial Non-Diagnostic FNA

Abstract Background In the case of a non-diagnostic thyroid fine-needle aspiration (FNA) biopsy result recent guidelines from the Bethesda System recommend repeat thyroid FNA after three months to prevent false-positive results. We aimed to examine our institutional data to determine whether the three-month period affects the diagnostic yield of repeat biopsies. Methods A retrospective review of patient records over a five-year period at our institution was performed. Patients who required repeat FNA due to non-diagnostic results were included. The time between the FNA biopsies, adequacy of the FNA specimens, as well as the surgical pathology diagnosis were analyzed. Results We identified 317 patients who required a repeat FNA. Of these, 96 (30.3%) patients had repeat FNAs less than three months after initial biopsy, while 221 (69.7%) patients had repeat FNAs in greater than three months. One hundred five of the patients were referred to our clinic with an initial non-diagnostic biopsy from an outside institution. Repeat FNA was non-diagnostic in 35 patients (11.04%) in the total study population. There was no difference in satisfactory diagnostic yield between repeat FNAs performed greater than three months (201 patients, 90.95%) or less than three months (81 patients, 84.38%) after the initial biopsy ( p =0.117). Of the 35 patients with repeat non-diagnostic biopsy, 17 patients underwent diagnostic lobectomy and 3 (17.6%) were found to have malignant disease. Conclusions Early (less than 3 months) repeat FNA does not affect diagnostic yield of the subsequent sample. Patients with suspicious thyroid nodules could therefore receive a repeat FNA as soon as needed, rather than waiting three months. The shortened biopsy interval would alleviate stress on patients with benign nodules and expedite surgical intervention in patients with malignancy.