Role of ultrasound markers in the first trimester for predicting twin-to-twin transfusion syndrome in monochorionic twins

Aim: to evaluate the relevance of ultrasound markers in the first trimester of pregnancy for predicting twin-to-twin transfusion syndrome (TTTS) in monochorionic twins. Patients and Methods: this prospective study was conducted from January 2016 to September 2022 and involved 178 women with monochorionic diamniotic twins in the first trimester (11+0–14+0 weeks) who underwent ultrasound once every 2 weeks. Group 1 included women who were later diagnosed with TTTS (n=68). Group 2 included women without TTTS (n=110). Results: in women who later developed TTTS, a significant increase in the discordance of the nuchal translucency (NT) thickness (p=0.036), increase in the pulsatile index (PI) of blood flow in the ductus venosus in one fetus higher than normative (p=0.036), a significant difference in the difference in the crown-rump length (CRL) (p=0.046), large arterial anastomosis in the placenta with predominant signal on one side of the isoline, and chorion previa (CP) (p=0.012) were reported. The difference in isovolumic relaxation time (IVRT) in the first trimester was more than 9 (6–11) ms in the TTTS group and 5 (4–9) ms in the non-TTTS group. However, this difference was insignificant (p=0.06). A prognostic model of TTTS was built based on ultrasound signs (NT thickness, CRL, IVRT, ductus venosus PI) using logistic regression. Conclusion: our study revealed risk factors for TTTS at the end of the first trimester in monochorionic twins. However, these risk factors require further evaluation in a large prospective case series of monochorionic twins. A method for predicting severe complications of monochorionic twins during early pregnancy provides an additional option for stratifying patients. KEYWORDS: multiple pregnancy, monochorionic twins, twin-to-twin transfusion syndrome, first trimester ultrasound markers, nuchal translucency thickness, crown rump length, ductus venosus pulsatility index, placental anastomosis, isovolumic relaxation time. FOR CITATION: Markova T.V., Kosovtsova N.V., Shumakov S.Yu., Chumarnaya T.V., Ermak E.M., Pospelova Ya.Yu. Role of ultrasound markers in the first trimester for predicting twin-to-twin transfusion syndrome in monochorionic twins. Russian Journal of Woman and Child Health. 2023;6(3):226–232 (in Russ.). DOI: 10.32364/2618-8430-2023-6-3-2.