Longitudinal reference ranges for serial measurements of myocardial performance index (MPI) by conventional and tissue Doppler in monochorionic diamniotic pregnancies at 17–26 weeks of gestation

Objectives To establish longitudinal reference ranges for fetal MPI measured by conventional Doppler (MPI) and by tissue Doppler (MPI') based on a prospective cohort of uncomplicated MCDA twin. Methods Single-centre observational study. We measured MPI and MPI' on the right and left ventricles three times between 17and 26 weeks of gestation. Second-degree fractional polynomials were used to obtain the best fitting curves in relation to gestational age (weeks) for each parameter. Multilevel modelling was used to estimate the reference percentiles. Appropriate back transformations were performed to obtain the gestational age-specific reference values. Results Eighty-three uncomplicated MCDA pregnancies were included in our study with a total of 249 observations. Fetal cardiac function was measured as MPI RV and LV, MPI' RV and LV at a mean gestational age of 18.3 (range 17.1-19.2), 22.3 (21.1-23.5) and 24.3 (22.6-26.2) weeks. The reference ranges for MPI LV, MPI RV, MPI' LV, MPI' RV at 18–24 weeks were constructed. Conclusions The present study provides additional data on fetal cardiac function in uncomplicated MCDA twin gestations, describing the evolution of novel parameters in both ventricles.