Use of the Foetal Myocardial Performance Index in monochorionic, diamniotic twin pregnancy: a prospective cohort and nested case-control study.

Aims: Assess clinical utility of the foetal Myocardial Performance Index (MPI) in evaluation and management of monochorionic, diamniotic twin (MCDA) pregnancies.

Methods: Prospective cohort of (a) initially uncomplicated MCDA (b) Complicated MCDA, including twin-twin transfusion syndrome (TTTS), selective intrauterine growth restriction (sIUGR), and liquor and/or growth discordance (L/GD) not meeting TTTS or sIUGR criteria. TTTS and sIUGR were case-control matched. Routine Dopplers and MPI were taken and correlated to diagnosis and final outcome.

Results: Twenty-six always uncomplicated pairs, 51 always complicated pairs, and seven uncomplicated to pathological pairs were included. TTTS recipient (n = 25) left and right MPI and intertwin difference (ITD) were significantly elevated, however, were already elevated in Stage I (n = 10), and did not predict progression or pregnancy outcome. sIUGR MPI (n = 11) did not differ significantly from control. Of 15-L/GD pairs, two that progressed to TTTS had significantly higher left and right MPI values in the future recipient (0.61 and 0.72) versus future sIUGR larger twins (0.48 and 0.51) or stable L/GD (0.47 and 0.52): p < .01 for all comparisons.

Conclusions: In this cohort, MPI did not add substantial diagnostic/prognostic information to current routine evaluation in established TTTS or sIUGR though potentially differentiated L/GD cases progressing to TTTS.