Accurate neurosonographic prediction of brain injury in the surviving fetus after the death of a monochorionic cotwin

Objective: To assess the feasibility of the prenatal diagnosis using fetal neurosonography of brain injuries in the surviving fetus after the demise of a monochorionic cotwin. Methods: This was a retrospective observational study in the period 1990-2004 of monochorionic twin pregnancies with a single fetal demise. A detailed sonographic evaluation of the intracranial anatomy of the surviving twin had been performed whenever possible using a multiplanar approach and from 1999, fetal magnetic resonance imaging was offered as well. Postnatal follow-up was obtained in all cases. Results: In six of nine cases, abnormal neurosonographic findings were identified including intracranial hemorrhage, brain atrophy, porencephaly and periventricular echogenicities evolving into polymicrogyria. Prenatal diagnosis of brain lesions was confirmed postnatally and all affected infants who survived had severe neurological sequelae. Two fetuses had normal cerebral structures both on the prenatal neurosonogram and on postnatal imaging and were following normal developmental milestones, one at 1 and the other at S years of age. In one case the neurosonographic examination was suboptimal and the infant was found at birth to have a porencephalic cyst. Fetal magnetic resonance imaging was performed in two cases and confirmed the ultrasound diagnosis. Conclusions: Prenatal neurosonography is a valuable tool for the prediction of neurological outcome in fetuses surviving after the intrauterine death of a monochorionic cotwin. Although our experience is limited, we suggest that magnetic resonance imaging should also be offered.