Early identification of umbilical blood flow restriction and maternal placental hypoperfusion with photoacoustic imaging.

In clinical practice, the prompt and accurate identification of acute fetal distress (AFD) is critical. Although cardiotocography and ultrasonography are the cornerstone clinical tools for fetal monitoring, they cannot quantitatively assess fetal cerebral hypoxia and carry inherent risks of underdiagnosis or false-positive interpretations. This study evaluates photoacoustic imaging (PAI) for early AFD detection. In mouse models, oxygen saturation (sO2) in the fetal brain and placenta was measured using PAI, demonstrating a significant sO2 decrease following placental blood flow obstruction - with more pronounced reductions observed in complete versus partial restriction cases. Crucially, a novel two-step PAI approach differentiated placental hypoperfusion from umbilical cord obstruction by analyzing distinct sO2 patterns in both placenta and fetal brain tissues. This distinction is clinically vital, as placental and cord-related AFD require different urgent interventions. PAI's ability to pinpoint the underlying cause highlights its potential for guiding precise treatment decisions.