Objective: This study was undertaken to evaluate intracranial magnetic resonance imaging abnormalities in the surviving fetus after a cotwin demise.
Study design: This is a retrospective observational study evaluating the intracranial findings of surviving twins after demise of a monochorionic cotwin. A total of 47 cases of cotwin demise were identified from an magnetic resonance imaging database consisting of all fetal magnetic resonance imagings performed at the University of California San Francisco. Twenty-one of these cases were monochorionic twins who had not undergone an intervention (fetal radiofrequency ablation and placental laser ablation) and these comprised the study group. The magnetic resonance imagings were reviewed by a pediatric neuroradiologist who was blinded to the ultrasound and clinical findings.
Results: The mean gestational age at the time of cotwin demise was 19(6/7) weeks (range 12(4/7) weeks-26(5/7) weeks) with an average interval of 4(3/7) weeks between the time of cotwin demise and fetal magnetic resonance imaging (range 0-12(1/7) weeks). Nine cases (41%) were associated with diagnosed twin-twin transfusion syndrome. Abnormal findings, including polymicrogyria, germinolytic cysts, intracranial hemorrhage, ventriculomegaly, and delayed sulcation were identified by fetal magnetic resonance imaging in 7 (33%) cases, the majority of which had a normal ultrasound.
Conclusion: Prenatal magnetic resonance imaging is a valuable tool in evaluating the fetal brain after a cotwin demise.