BACKGROUND
Thyroid nodules are very common and are found in anywhere from 30-50% of individuals in the United States. Thyroid ultrasound is the main imaging study used to evaluate thyroid nodules. Based on the appearance of the nodule on ultrasound as well as the size of the nodule, further evaluation such as a biopsy is determined. The concern about a thyroid nodule is whether it is a thyroid cancer. Overall, only 5-6% of nodules are cancerous. Further, up to half of the cases of thyroid cancer are small papillary thyroid cancers that likely will never become a significant concern or cause death. This high incidence and low death rate have been interpreted to be a result of overdiagnosis (i.e., the detection of small cancers that will never progress to cause harm). This overdiagnosis seems to be mainly due to widespread use of ultrasound that identifies small nodules and, as a result, small thyroid cancers. Indeed, thyroid microcarcinomas are more likely to be detected by ultrasound than by other imaging methods.

The American Thyroid Association has published guidelines as to the appropriate use of thyroid ultrasound, as do several other national organizations. This study aimed to evaluate the frequency of thyroid ultrasound studies that are deemed “unnecessary” by clinical practice guidelines and/or expert recommendations.

THE FULL ARTICLE TITLE
Edwards MK et al 2021 Inappropriate use of thyroid ultrasound: A systematic review and meta-analysis. Endocrine 74:263–269. PMID: 34379311.

SUMMARY OF THE STUDY
This study was done to look at the use of thyroid ultrasound in the management of patients suspected to have thyroid nodules. Seven studies were included in the final analysis and ~1,500 patient charts were studied. The concept of “inappropriate” was variably defined, using clinical practice guidelines, authors’ opinions, or third-party expert reviewers.

Overall, the frequency of “unnecessary” thyroid ultrasound examinations was 46% and decreased to 34% when including only studies using guideline-based definitions for ordering the study. The frequency of ultrasound examinations due to other nonspecific symptoms without a palpable mass in the thyroid was 11%.

WHAT ARE THE IMPLICATIONS OF THIS STUDY?
Thyroid ultrasound is a commonly used imaging technique. A better definition of clinical need for doing this procedure is of great importance. This will avoid unnecessary over-use and diagnosis of thyroid nodules which may often lead to further testing and procedures. This will reduce cost of care and patient anxiety. Better clinical guidelines and provider education may help reduce the unnecessary use of thyroid ultrasound.

— Vibhavasu Sharma, MD

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