“The number of thyroid ultrasounds performed in the United States has increased fivefold since 2002. This substantial increase produces a significant strain on healthcare resources and leads to over-detection and overtreatment of benign thyroid nodules and small, indolent cancers with questionable clinical relevance,” wrote Elena Kennedy, MD, then a medical student in the department of surgery at the University of Wisconsin School of Medicine and Public Health, Madison, and colleagues.
The data, published online in Thyroid, come from a retrospective chart analysis of more than 1700 people who underwent dedicated (ie, specifically to look for a nodule) thyroid ultrasounds at a tertiary academic center. The rates of detecting both nodules and biopsy-recommended nodules were highest when the indication was a nodule seen incidentally on other imaging (aka “incidentaloma”) and lowest when the ultrasound was ordered because the patient had either metabolic or compressive symptoms.
And for the most commonly listed indication, a suspected palpable nodule, nearly half of the ultrasounds found no nodule, and only one in five detected a nodule that warranted a biopsy.
The principal investigator of the study David O. Francis, MD, an otolaryngologist at the University of Wisconsin, Madison, said in an interview, “Thyroid cancer has grown in incidence three to four times over the last 30 years without a good explanation for why…It seems to be that we’re detecting smaller and smaller nodules…Why are people being referred for all these ultrasounds? We looked for the upstream factors.”
One clear clinical implication of the new data, Dr. Francis noted, is that “if someone has compressive symptoms including dysphagia, swallowing problems, voice change, or globus sensation, ultrasound should not be the first way to work them up…It would be smarter to have someone evaluate their voice or their swallowing to see if there’s another reason besides the thyroid. The thyroid would have to get pretty big to cause dysphagia or swallowing problems.”
No Current Guidelines Advise When not to Order a Thyroid Ultrasound
Problematically, while there are professional society guidelines for what to do when a thyroid “incidentaloma” is found and other specific situations, there are no overall guidelines addressing when it’s appropriate to order a thyroid ultrasound, Dr. Kennedy, now an otolaryngology resident at the Indiana University of Indianapolis, and colleagues, point out.
According to Dr. Francis, “Ultrasounds are low cost and low risk. Those two factors result in people ordering more tests…The problem with that is we find things, and then we have to figure out what to do with them. That leads to incidentalomas, the surveillance, worry and anxiety, and costs…It’s tricky. We don’t want to discourage people from ever ordering ultrasounds, but there need to be some guidelines around when it’s appropriate to order.”
Asked to comment, Trevor E. Angell, MD, associate medical director of Thyroid Center at Keck School of Medicine of the University of Southern California, Los Angeles, said that the study is “clinically very important.”
Dr. Angell pointed out that the current American Thyroid Association (ATA) guidelines on thyroid nodule management, of which he is an author, recommend ultrasound for a known or suspected nodule. But he added, “there certainly should be a message that obtaining ultrasound for these other reasons are less likely to identify a nodule or anything causative. Whether it’s gastroesophageal reflux or allergic rhinitis or vocal cord dysfunction, an ultrasound isn’t a good test for those either.”
Dr. Angell said that the next ATA thyroid nodule guidelines, expected out in 2024, will address this topic more fully, but he couldn’t provide more specific information because the document is still in development. He did say, however, “Addressing when not to do an ultrasound will be an important consideration in the next guidelines.”