Delta MCA-PSV MoM in detecting TAPS

Objectives:

To evaluate the relationship between inter-twin differences in hemoglobin concentrations at birth and fetal inter-twin differences in middle cerebral artery peak systolic velocities (MCA-PSV) in monochorionic diamniotic twins (MCDA).

Methods:

This was a retrospective cohort study of MCDA twin pregnancies delivered between January 2012 and January 2018. All pregnancies with measurements of MCA-PSV within seven days of delivery and where neonatal Hb concentrations were available were included. We investigated the correlation between fetal inter-twin differences of MCA-PSV expressed in multiples of the median (MoM) and neonatal hemoglobin differences.

Results:

A total of 154 out of 256 MC twin pregnancies fulfilled the inclusion criteria. The fetal inter-twin MCA-PSV MoM differences correlated positively with the neonatal inter-twin hemoglobin differences (r = 0.79; P < 0.001). The 90th centile for hemoglobin differences was 7.25 g/dl. There were 15 (9.7%) cases with a Hb difference ≥7.25 g/dl at birth. Receiver-operating characteristic (ROC) curve was constructed and showed a high accuracy of fetal inter-twin MCA-PSV MoM differences for the prediction of neonatal inter-twin Hb difference ≥7.25 g/dl at birth (area under the curve (AUC), 0.976; 95% CI, 0.935 – 0.993; P = 0.012). The optimal cut off for MCA-PSV MoM difference was 0.373 with a sensitivity of 93% and a specificity of 96%. The false positive and false negative rates were 4.3% (6/139) and 6.7% (1/15), respectively.

Conclusion:

Our findings show that fetal inter-twin MCA-PSV MoM difference is a good predictor of neonatal inter-twin hemoglobin difference.