Superb Micro-Vascular Imaging in Prenatal Ultrasound Diagnosis of Placental Infarction: A Case Report.

Background: Placental infarction refers to a localized area of ischemic villous necrosis resulting from the interruption of maternal blood flow to the intervillous space, which can be attributed to spasm, stenosis, or occlusion of the decidual spiral artery caused by systemic or localized maternal vascular disease. The presence of large placental infarcts may pose significant risks to fetal well-being, including intrauterine growth retardation, fetal distress, and even fetal demise. Although placental infarction is commonly identified during postnatal pathological examinations, its prenatal diagnosis through ultrasound remains challenging and has been rarely reported.

Case Presentation: This report presents a case of acute placental infarction diagnosed by prenatal ultrasound using Superb Micro-vascular Imaging (SMI) technology. At 23 weeks' gestation, the ultrasound revealed that the placenta was attached to the left lateral and posterior walls of the uterus, showing localized thickening. Within this area of thickening, there were observed inhomogeneous hypoechoic regions. Superb Micro-vascular Imaging (SMI) revealed an abnormal echogenic region within the thickened placental tissue that lacked microvascular blood flow signals, but showed surrounding vascularity. Visually, this elliptical-shaped echogenic region enveloped by microvascular blood flow. From the 29th weeks of gestation onward, ultrasound suggested that the fetus was small for gestational age. A live baby weighing 2360g was delivered by cesarean section at 37 weeks' gestation. The placenta was approximately 20×18 × 3 cm with large grayish-yellow infarcts.

Conclusion: SMI allows rapid screening of large placental infarcts and easy detection of regions without normal vessel trees, thereby reducing missed diagnoses. Infarct area is easily measured by measuring the area surrounded by small blood vessels, especially in acute placental infarction, which is very helpful in accurately determining infarct size.