What are the most common first-trimester ultrasound findings in cases of Turner syndrome?

Objectives: To identify the most common first-trimester ultrasound findings in Turner syndrome (TS). To evaluate which first-trimester findings can be best used to predict the likelihood of TS. Methods: This was a prospective study, based on singleton pregnancies. The referrals included 6210 patients. Scan protocol covered a review of the early fetal anatomy and markers of aneuploidy. Results: Study population comprised 5644 pregnancies: 5613 with a normal karyotype and 31 cases of TS. Statistically significant differences (p < 0.05) were found between euploidy and TS groups in terms of nuchal translucency (NT; 1.7 mm versus 8.8 mm) and fetal heart rate (FHR; 160 versus 171 beats per minute). None of the TS cases demonstrated absent markers of aneuploidy as opposed to 5133 (91.4%) cases of euploidy. NT and abnormal DV flow (aDV or revDV) were the most common markers found in combination in TS cases (n = 17; 54.8%). 27 (0.5%) cases of euploidy and 17 (54.8%) cases of TS revealed congenital heart defects. Fetal hydrops was observed in 14 cases of TS (43.8%) and in 5 of euploidy (0.1%). In backward regression model, NT > 3.5 mm and right dominant heart (RDH) augmented the risk of TS risk by 991 and 314 times, respectively. Conclusions: First-trimester sonography is a feasible method to identify the most characteristic features of TS fenotype. When the first-trimester pattern of TS is considered, a highly thickened NT, FHR above the 95th percentile, abnormal ductus venosus velocimetry, fetal hydrops, and RDH should be specifically searched for.