OP30.05: Can middle cerebral artery peak systolic velocity predict polycythemia in monochorionic diamniotic twins? Evidence from a longitudinal study

Abstract

Objectives: Antenatal diagnosis of twin anemia-polycythemia sequence (TAPS) in monochorionic diamniotic (MCDA) twin pregnancies is based on elevated peak systolic velocity in the middle cerebral artery (MCA-PSV) in the donor twin and decreased MCA-PSV in the recipient twin. However, the association between these parameters and neonatal polycythemia has not been established. The aim of this study was to determine whether MCA-PSV can predict polycythemia in MCDA pregnancies. Methods: Prospective cohort study of 69 MCDA pregnancies, recruited at 14-16 weeks of gestation. Fetal MCA Doppler waveforms were recorded every 1-2 weeks from 14-16 weeks of gestation till delivery. Neonatal hematocrit level was determined in all twins. Polycythemia was defined as hematocrit ≥ 65%. Results: Thirteen (9.4%) neonates were diagnosed with polycythemia and 7 pregnancies (10.1%) met the criteria of TAPS. In pooled analysis, MCA-PSV was negatively correlated with neonatal hematocrit (p = 0.017; r = -.215) and was significantly higher among anemic fetuses compared to controls (1.14 MOM vs 1 MOM, p = 0.009). While MCA-PSV was similar among polycythemic and normal twins (0.95 MOM vs 1 MOM, p = 0.35), intertwin difference in MCA-PSV (Delta MCA-PSV) was positively correlated with intertwin hematocrit difference (p = 0.002; r = .394). Moreover, twin pregnancies with intertwin hematocrit discordance of more than 24% had significantly higher Delta MCA-PSV compared to twin pregnancies with intertwin hematocrit discordance of less than 24% (12 vs 5, p = 0.008). Conclusions: MCA-PSV is not significantly decreased among polycythemic monochorionic twins. However, Delta MCA-PSV is associated with large intertwin hemoglobin difference and may be superior to the conventional methods in the risk assessment of TAPS.

Uncommon complications of monochorionic twin pregnancies: Twin anaemia-polycythaemia sequence

“…had a Delta MCA‐PSV >0.7, which suggests that this criterion may be more effective at identifying TAPS than specified cut‐offs. This supports the conclusions of Fishel‐Bartal et al . and Lucewicz et al .…”

“…had been adopted for this study, 4/14 TAPS cases would have been excluded from diagnosis. Delta MCA‐PSV MoM was calculated for this study, as suggested by Fishel‐Bartal et al ., with an average of 0.83 between the polycythaemic and anaemic fetuses. Two of the four cases excluded by the diagnostic criteria proposed by Robyr et al .…”

“…Robyr et al ., however, define the cut‐off for the polycythaemic twin as <0.8 MoM. Additionally, Fishel‐Bartal et al . suggest that Delta MCA‐PSV measurements are more effective than specified cut‐offs.…”

Review of the correlation between blood flow velocity and polycythemia in the fetus, neonate and adult: appropriate diagnostic levels need to be determined for twin anemia-polycythemia sequence

“…Alternatively this could be achieved with a retrospective multicenter evaluation matching neonatal hemoglobin level with recent antenatal MCA‐Vmax. In addition to defining a cut‐off to diagnose the polycythemic fetus, it may also be beneficial to evaluate the intertwin discordance of MCA‐PSV, as suggested recently.…”