Context: Recently published guidelines are discordant regarding diagnostic approaches to small (10–14 mm) thyroid nodules.

Objective: To explore the relative desirability of alternative diagnostic approaches to small thyroid nodules using decision analysis.

Design: Four diagnostic approaches to a 10–14 mm thyroid nodule are modeled: (1) observation only, consistent with American Thyroid Association (ATA) guidelines; (2) routine fine needle aspiration biopsy (FNAB), an approach traditionally chosen by many endocrinologists and consistent with ATA guidelines; (3) FNAB only when microcalcifications are present, as recommended by Society of Radiologists in Ultrasound (SRU) guidelines; and (4) FNAB only when the nodule is hypoechoic and has at least one other ultrasonographic risk factor, as endorsed by American Association of Clinical Endocrinologists (AACE) guidelines.

Main Outcome Measures: Expected values; a priori likelihoods of prespecified outcomes; and two-way sensitivity analyses based on the utility of (1) observation only in the setting of thyroid cancer and (2) thyroid surgery for benign, asymptomatic thyroid disease.

Results: Expected values (EVs) were similar among decision alternatives modeling SRU guidelines, AACE guidelines, and routine observation (EVs from 0.912 to 0.927). Routine FNAB had the lowest EV (0.757 to 0.861), primarily related to a high a priori likelihood of having surgery for a benign nodule.

Conclusions: As a general approach to 10–14 mm thyroid nodules, routine FNAB appears to be the least desirable. This analysis offers additional data that physicians can use when choosing diagnostic approaches to small thyroid nodules based on perceived risks of delayed cancer diagnosis and unnecessary thyroid surgery.