Circumvallate placenta, first trimester

This code signifies a condition where the chorionic plate of the placenta is smaller than the basal plate, resulting in the fetal membranes folding back on themselves and forming a thick, raised ring around the placental margin. This anatomical anomaly is identified during the first trimester of pregnancy.

Use this code when documentation explicitly states a diagnosis of circumvallate placenta identified during the first trimester. This diagnosis is typically made via ultrasound imaging. Supporting documentation should include sonographic findings detailing the characteristic placental morphology.

• Ensure the documentation specifies "circumvallate placenta" and not a similar condition like circummarginate placenta.
• Verify the trimester of diagnosis; this code is specific to the first trimester.
• Code any associated complications or maternal conditions separately.