# Does normal fetal brain imaging in monochorionic twins following co-twin fetal demise eliminate the risk of adverse neurodevelopmental outcome?

## TL;DR

Normal brain imaging in surviving monochorionic twins after co-twin death does not fully rule out developmental issues.

## Contribution

Shows that normal fetal brain imaging does not eliminate the risk of adverse neurodevelopmental outcomes in these twins.

## Key findings

- 45.4% of surviving twins with normal imaging had abnormal developmental evaluations.
- Two of 17 imaged fetuses showed CNS injury, with one showing mild speech delay.
- Urgent delivery due to fetal distress occurred in two cases, bypassing imaging.

## Abstract

To assess the residual risk of long-term adverse neurodevelopmental outcomes in monochorionic twins following co-twin fetal demise and normal fetal brain imaging.

All monochorionic twin pregnancies with co-twin fetal demise were included. Patients were identified through a search of inpatient medical records for co-twin fetal demise. Cases involving fetal demise following intrauterine procedures (e.g., laser ablation or termination of pregnancy following findings on fetal brain imaging) were excluded. Following co-twin demise, fetal brain imaging, including serial neurosonogram and fetal brain MRI, was performed on the surviving fetus. Neurodevelopmental outcomes were assessed postnatally using standardized age-appropriate developmental evaluation of personal–social, language, gross and fine motor skills, as well as hearing and vision screening. Additionally, parents completed a phone-based adaptive behavior questionnaire using the Vineland-II Adaptive Behavior Scales (VABS-II).

Nineteen patients met the inclusion criteria. Two patients underwent urgent cesarean delivery due to fetal distress following co-twin demise and did not undergo any imaging. Of the 17 patients who underwent fetal brain imaging, 2 had evidence of CNS injury, one of whom later presented with mild speech delay, and the other who achieved an adequate VABS-II score. Among the fetuses with normal brain imaging and available follow-up, 45.4% (5/11) had abnormal developmental evaluations including one global delay, one motor delay, one mild hypotonia, and two moderately low scores on VABS-II.

Normal fetal CNS imaging following co-twin fetal demise in monochorionic twins does not guarantee normal neurodevelopmental outcome. This residual risk should be clearly discussed with parents during counseling to aid clinical decision- making.

The online version contains supplementary material available at 10.1007/s00404-025-08149-6.