Objective

Monochorionic pregnancies are at increased risk of single intrauterine death (sIUD) and subsequent brain injury in the survivor due to shared placentation. We assessed the association between middle cerebral artery peak systolic velocity (MCA PSV) and cerebral injury on magnetic resonance imaging (MRI) and characterized the association between cerebral findings on diffusion weighted imaging (DWI) and T2-weighted imaging following spontaneous sIUD.

Methods

Retrospective cohort of monochorionic pregnancies complicated by spontaneous sIUD followed at a tertiary center between 1/2008 and 1/2020. Pregnancies with sIUD post laser, selective feticide, double IUD occurring on the same day, and sIUD < 14 weeks were excluded, as were cases in which MCA PSV was not measured or DWI MRI was not performed. MCA PSV Dopplers were compared with MRI findings to predict subsequent cerebral injury, and DWI findings were analyzed and compared to susceptibility-weighted imaging (SWI) and T2 MRI for diagnostic accuracy.

Results

We assessed 64 monochorionic pregnancies complicated by spontaneous sIUD. Of these, 47 (73.4%) pregnancies underwent fetal brain MRI and met inclusion criteria. Sixteen (34.0%) fetuses demonstrated cerebral injury on MRI done at a median interval of seven days from demise diagnosis to MRI. Fetuses with an increased MCA PSV>1.5 MoM following sIUD were significantly more likely to demonstrate cerebral injury on MRI than those with a normal MCA PSV (39.1% versus 13.0%, p=0.04). The sensitivity and specificity of MCA PSV>1.5 MoM for cerebral injury on MRI were 68.8% (95%, CI 41.3% – 88.9%) and 61.3% (95% CI, 42.2% - 78.2%), respectively. Patterns of early cerebral injury on T2 MRI included acute or subacute tissue swelling (n=6), parenchymal atrophy (n=7), loss of cortical ribbon (n=1), and hemorrhage (n=8). Early MRI within ~ two weeks of demise diagnosis demonstrated abnormal DWI along with coexisting SWI and T2 sequelae in 56% (9/16) of the cases. When DWI was normal and a second later MRI was performed (n=7) there were no ischemic changes evident on T2.

Conclusion

Increased MCA PSV is associated with but poorly predicts cerebral injury after sIUD. Early MRI with DWI within approximately two weeks of demise diagnosis is valuable in identifying any cerebral injury.

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