Thyroid nodules and cancer in women with positive thyroid screening in pregnancy: a double-centric, retrospective study.

OBJECTIVE: Thyroid nodules are a common finding in the general population. The primary aim of the study was to determine the prevalence of thyroid nodules and cancer found by ultrasound in women who underwent screening for thyroid dysfunction during pregnancy.

DESIGN: A double-centric, retrospective, cohort study.

PATIENTS AND METHODS: We searched through medical records, including thyroid ultrasonography, of pregnant women positively screened for thyroid disorders (using TSH and thyroid antibodies) from unselected population ("universal screening group", N=690), and of women who underwent the testing based on the presence of clinical risk factors defined by American Thyroid Association ("case-finding group", N=249).

RESULTS: Prevalence of benign and malignant thyroid nodules was lower in the "universal screening group" than in the "case-finding group" (9.9% vs. 17.7%, P=0.002, and 0.9% vs. 7.2%, P<0.001, respectively). Consistently, the thyroid cancer rate was lower among the nodules in the "universal screening group" than in the "case-finding group'' (8.1% vs. 29.0%, P=0.003). Ultrasound EU-TIRADS category ≥4 had a 95.8% sensitivity for thyroid cancer. In palpable nodules, the prevalence of cancer was significantly higher than in the non-palpable ones (44.0% vs. 2.2%, P <0.001). In a multivariate regression analysis, thyroid nodules were associated with a history of infertility and parity.

CONCLUSIONS: Compared to the data from cancer registries, universal screening allowed detecting thyroid cancer in pregnancy 3 to 5 times more frequently, but the cancer rate among nodules (8.1%) did not differ from the common population. Ultrasound had very good sensitivity for thyroid cancer in pregnancy.