Right ventricular outflow tract abnormalities in monochorionic twin pregnancies without twin-to-twin transfusion syndrome: Prenatal course and postnatal long-term outcomes.

Objectives: Right ventricular outflow tract abnormalities (RVOTA) have been mostly reported in recipient twins (RT) of monochorionic/diamniotic (MC/DA) twin pregnancies with twin-to-twin transfusion syndrome (TTTS). Aim of the study was to describe RVOTA detected in MC/DA pregnancies without TTTS.

Methods: Cases of RVOTA were retrieved from our database among all MC/DA pregnancies without TTTS from 2009 to 2018.

Results: Out of 891 MC/DA twin pregnancies without TTTS, 14 (1.6%) were associated with RVOTA: 10 pulmonary stenosis (PS), one steno-insufficiency, one insufficiency and two atresia (PA). In 93% of cases (13/14), pregnancy was complicated either by amniotic fluid discrepancy (AFD) or by TAPS or mostly by selective fetal growth restriction (sFGR) (11/13: 85%), involving predominantly (10/11: 91%) the large twin, with high incidence (9/11: 82%) of sFGR and AFD coexistence. Eight out of 14 (57%) survived after the perinatal period (7 PS, 1 PA). Five (62%) underwent pulmonary balloon valvuloplasty, whereas 3 children still showed persistent mild PS at cardiac follow up after 1 year of life.

Conclusions: RVOTA can occur in MC/DA pregnancies without TTTS, particularly when other complications coexist. In complicated cases specialized fetal echocardiographic evaluation is recommended during pregnancy; RVOTA cases should be delivered in a tertiary level center, where cardiologists are available.