Brain injury in twin anemia-polycythemia sequence: prevalence, severity and long-term neurodevelopmental outcome.

objectivesThe primary objective of this study was to evaluate the prevalence, type and severity of pre- and postnatal brain injury in monochorionic twins with twin anemia-polycythemia sequence (TAPS). Secondary objectives were to conduct within-pair comparisons between donor and recipient twins of structural cranial ultrasound (cUS) measurements and to evaluate the association between brain injury and neurodevelopmental outcome in TAPS.

methodsThis was a single-center retrospective cohort study including cases of spontaneous and postlaser TAPS delivered at the Leiden University Medical Center, Leiden, The Netherlands, between May 2002 and December 2024. We evaluated all available pre- and postnatal neuroimaging, including ultrasound and magnetic resonance imaging, to identify brain injury. Structural measurements were obtained from cUS performed within 3 days after birth, and were included only if high-quality images were available for both cotwins. Neurodevelopmental outcome was evaluated using standardized age-appropriate assessments for cognitive and motor development.

resultsA total of 256 infants were included from 132 pregnancies (124 twin pairs and eight single survivors). Brain injury was observed in 16.8% (43/256) of infants, of which 93.0% (40/43) had a postnatal origin. There was no significant difference in the prevalence of brain injury between cases of spontaneous TAPS (13.5% (20/148)) and postlaser TAPS (21.3% (23/108)) (P = 0.1). Severe brain injury was observed in 7.4% (19/256) of the infants, with no significant difference between donor twins (6.5% (8/124)) and recipient twins (8.3% (11/132)) (P = 0.54). Lower gestational age at birth was an independent risk factor for brain injury (odds ratio, 1.31 (95% CI, 1.15-1.50); P < 0.01). Among infants with moderate-to-severe neurodevelopmental impairment (NDI), 57.1% (8/14) had evidence of brain injury. Brain injury alone did not account for the impairment in 71.4% (10/14) of cases with moderate-to-severe NDI.

conclusionsBrain injury was observed in approximately one-fifth of infants with TAPS, was primarily postnatal in origin and was strongly associated with preterm birth. In the majority of infants with moderate-to-severe NDI, the impairment could not be explained by the observed severe brain injury alone, emphasizing its probable multifactorial origin. © 2026 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.