Twenty-one-gauge needles provide more cellular samples than twenty-five-gauge needles in fine-needle aspiration biopsy of the thyroid but may not provide increased diagnostic accuracy

The technique of fine-needle aspiration (FNA) biopsy of the thyroid is impo rtant to evaluate malignancy in thyroid nodules. Eighty-five percent of thy roid INA procedures lead to sufficient cellular material for diagnosis. Wit h more cells aspirated, the chance of sufficiency for diagnosis increases. Large-bore needles lead to more cellular material being aspirated but blood ier specimens that may interfere with cytologic interpretation. Small-bore needles may result in too few cells for diagnosis. We conducted a randomize d prospective study contrasting 21-gauge and 25-gauge needles in the evalua tion of 50 consecutively enrolled nodules at our institution. In our invest igation, 21-gauge needles more frequently provided superior biopsy specimen s (50%) than did 25-gauge needles (18%). In the remaining specimens (32%), the 21-gauge and 25-gauge needles provided similar cellular material. The r ate of sufficient samples was the same. We conclude that use of 21-gauge ne edles results in more cellular specimens but may not result in increased di agnostic accuracy.