To assess the application value of ultrasonic Doppler in evaluating the therapeutic effects of radiofrequency ablation (RFA) and fetal reduction for twin-to-twin transfusion syndrome (TTTS).

Twenty-five monochorionic twins who underwent RFA at our hospital from August 2020 to February 2022 were retrospectively selected. Ultrasonographic Doppler measurements of the umbilical artery (UA), ductus venosus (DV), middle cerebral artery (MCA), and umbilical vein were performed before surgery and 1, 2, and 7 days after surgery. The retained fetuses were divided into the recipient group (13 cases) and the donor group (12 cases), and the differences in the parameters among the groups of fetuses before and at 1, 2, and 7 days after RFA were compared by repetitive measure analysis of variance (ANOVA), followed by pairwise comparison using the Bonferroni method. The Fisher exact probability method was used to compare the difference in the proportion of abnormal DV and the difference of preserved fetal survival between groups. All postoperative fetal clinical outcomes were followed up.

Among all the TTTS cases included, 5 were Quintero stage Ⅳ, 12 stage Ⅲ, 6 stage Ⅱ, and 2 stage Ⅰ; 7 were complicated with selective intrauterine growth restriction (sIUGR), 3 were twin anemia-polycythemia sequence (TAPS), and 1 was structural malformation in one twin. Doppler evaluations showed that: (1) UA: the differences of peak systolic velocity/peak diastolic velocity (S/D) and pulsatility index (PI) were statistically significant at different time points before and after surgery (P＜0.05 for all). Compared with the values at 1 day postoperatively, preoperative S/D (4.49±1.35 vs 3.88±1.13) and PI (1.45±0.30 vs 1.31±0.25) of the recipident group, and PI (1.58±0.38 vs 1.27±0.20) of the donor group showed significant differences (P=0.004, 0.010, and 0.003, respectively); (2) MCA: there were significant differences in fetal PSV, PI and cerebroplacental ratio before and after surgery between the two groups (P＜0.05 for all); (3) DV: the proportion of cases with DV abnormality before surgery was 38.5% (5/13) in the recipient group and 8.3% (1/12) in the donor group, and there was no significant difference between the two groups at different time points before and after surgery (P＞0.05 for both). A total of 20 preserved fetuses survived, and the overall survival rate was 80.0% (20/25). There was no significant difference in the survival rate between the donor and recipient groups [75% (9/12) vs 84.6% (11/13), P＞0.05].

Most TTTS fetuses have abnormal hemodynamics. The application of ultrasound Doppler can dynamically evaluate the status of the retained fetuses' systemic blood circulation and intuitively judge whether the fetuses have anemia and abnormal cardiac function, which is of great value in the postoperative evaluation of the therapeutic effects of RFA.