Doppler abnormalities in monochorionic diamniotic twin pregnancies with discordant growth.

OBJECTIVE: We studied whether abnormal umbilical artery (UA) Doppler flow velocity waveforms occur with higher frequency in monochorionic diamniotic (MCDA) twin gestations with discordant fetal growth and whether this impacted neonatal outcome.

STUDY DESIGN: We performed a retrospective study of MCDA twin pairs. We collected data from an electronic medical record. We classified pregnancies as discordant if there was at least 20% birth weight discordance. Abnormal UA Doppler velocity waveforms included absent or reversed end diastolic flow. We analyzed the data with chi square, Student's t-test and analysis of variance as appropriate.

RESULT: Seventy-three twin pairs met criteria for inclusion, including 16 with discordant growth. The discordant group was significantly more affected with twin-to-twin transfusion syndrome (TTTS) (P=0.02). The smaller fetuses in discordant pairs were more likely to display abnormal UA Doppler flow velocity waveforms (P<0.01). These neonates also had lower Apgar scores (P=0.03) and were more likely to require care in a neonatal intensive care unit. Our findings persisted after excluding pregnancies with TTTS.

CONCLUSION: In MCDA twin gestations complicated by discordant growth, there is an increased frequency of abnormal UA Doppler flow velocity waveforms in small fetuses, and these neonates face clinical challenges after birth.