Correlation between abnormal placental appearance at routine 2nd trimester ultrasound scan and histological examination of the placenta after birth.

Ultrasound imaging of the placenta and its relationship to poor perinatal outcome has been studied since 1973. Studies have predominantly focussed on placental morphology in the third trimester or in high-risk pregnancies. We aimed to correlate abnormal placental appearances identified in the second trimester with histological appearances. We present four cases of abnormal placental morphology detected at the 20 week routine ultrasound scan in low-risk women and relate them to histological origins, which often involved areas of villous infarction. Abnormal placental appearances at routine second trimester anomaly ultrasound scans might identify women with placental dysfunction who merit increased fetal surveillance in the third trimester.