OP22.06: Monochorionic twin pregnancies complicated by an anomalous co-twin: fetal magnetic resonance imaging after radiofrequency ablation

Abstract

To examine the fetal brain of the surviving co-twin with magnetic resonance imaging (MRI) after radiofrequency ablation (RFA) in monochorionic diamniotic twin gestations and to determine if selective reduction by RFA is associated with intracranial injury. This is a retrospective case series of all monochorionic diamniotic twin gestations complicated by an anomalous co-twin that underwent selective reduction via RFA and had follow-up fetal MRI studies between March 2002 and March 2009. Subjects were identified through our center's database, which included corresponding fetal MRI results that were reviewed by a neuroradiologist. Fetal MRI intracranial findings were compared to prenatal ultrasound and, when available, judged against postnatal imaging. Eleven fetal MRI studies were performed after RFA to assess for evidence of neurological injury in the surviving co-twin. RFA was performed for monochorionic diamniotic twin pregnancies discordant for fetal anomalies including: anencephaly (n = 3, 27%), twin-twin transfusion syndrome (n = 2, 18%), severe intrauterine growth restriction (n = 2, 18%), twin-reversed arterial perfusion (TRAP) sequence (n = 1, 9%), limb-body wall defect (n = 1, 9%), cystic hygroma/hydrops (n = 1, 9%), and renal anomalies (n = 1, 9%). Fetal karyotyping was obtained in 7 cases (64%), all of which were euploid. The mean gestational age at the time of RFA was 19.0 weeks (range 16.6 to 22.3). The mean interval between RFA and fetal MRI was 3.2 weeks (range 1.9 to 5.3). Fetal MRI demonstrated normal intracranial anatomy in 100% of cases (11/11). All subsequent antenatal ultrasound studies of the viable co-twin demonstrated normal fetal intracranial anatomy. Postnatal imaging was available in 6 cases (55.5%) of cases, which were all normal. Preliminary data suggest the selective reduction of an anomalous twin of a monochorionic diamniotic gestation via RFA is not associated with intracranial injury in the surviving co-twin.