Different risk of acute feto-fetal transfusion in basic clinical subtypes of monochorionic twins.

Analysis of the potential risk of acute feto-fetal transfusion (aFFT) in different clinical types of monochorionic twins using an in vitro placental simulation model. The prospective study analyzed 157 fresh MC placentas from 2014 to 2020, excluding those with intrauterine intervention. A specially designed protocol was used for their preparation and analysis. The study included 108 placentas with an uncomplicated course, 31 cases of selective fetal growth restriction (sFGR), and 18 cases of twin-to-twin transfusion syndrome (TTTS). The number and types of anastomoses, umbilical cord insertion distances (UCID), and placental areas for each fetus were statistically analyzed. The primary objective was to assess differences in aFFT among various MC twin subtypes. The secondary objectives were to identify risk factors associated with the development of aFFT. 76/157 (48.4 %) cases of aFFT were confirmed, with an average transfusion time of 1 mL in 50 s (8-240 s). The occurrence of aFFT in uncomplicated, sFGR, and TTTS placentas was 62,5 %, 50,9 %, and 5,9 %, respectively (p < 0.001). The representation of AA anastomoses was significantly higher in the sFGR and uncomplicated groups compared to TTTS (84.4 % and 80.6 % vs. 11.8 %; p < 0.001). Besides the presence of AA anastomosis, the main independent risk factor for the development of aFFT is its diameter (p < 0.001). The potential risk of aFFT differs significantly among individual clinical subtypes of MC twins, depending on the presence and size of AA anastomosis.