Fig 1.
MC: monochorionic.
Table 1.
Characteristics and outcome of the study population.
Table 2.
Transformation applied to normalize the variable, fractional polynomial chosen to estimate the median, and Interclass Correlation Coefficient (ICC).
Fig 2.
Left panels: umbilical artery pulsatility index (UA-PI), middle cerebral artery pulsatility index (MCA-PI), middle cerebral artery peak systolic velocity (MCA-PSV) and ductus venosus pulsatility index (DV-PI) values in 300 uncomplicated monochorionic twin fetuses between 20 and 37 weeks of gestation; the lines indicate the estimated 3rd, 5th, 10th, 50th, 90th, 95th,97th centiles. Right panels: comparison of the 5th, 50th and 95th estimated centiles curves of MC twins (present study, black lines) and singleton reference values by Acharya et al.[5] for UA-PI, Ebbing et al.[6] for MCA-PI and PSV, and Kessler et al.[7] for DV-PI (grey lines).
Table 3.
Gestational age (GA)-specific longitudinal reference centiles for umbilical artery pulsatility index (UA-PI).
Table 4.
Gestational age (GA)-specific longitudinal reference centiles for middle cerebral artery pulsatility index (MCA-PI).
Table 5.
Gestational age (GA)-specific longitudinal reference centiles for middle cerebral artery peak systolic velocity (MCA-PSV).
Table 6.
Gestational age (GA)-specific longitudinal reference centiles for ductus venosus pulsatility index (DV-PI).
Fig 3.
Middle cerebral artery peak systolic velocity (MCA-PSV) multiples of the median (0.8, 1.0, 1.5) derived from the present study (continuous lines), and comparison of MCA-PSV 1.5 MoM derived from the present study and from the MC twin studies of Klarisch et al. [21] and Mulcahy et al. [12], and the singleton cohort of Ebbing et al. [6].
Table 7.
Middle cerebral artery peak systolic velocity multiples of the median (MCA-PSV MoM) (0.8, 1.0, 1.5, 1.7) derived from 300 uncomplicated monochorionic twin foetuses from 20 to 37 weeks of gestation.