Circumvallate placenta, unspecified trimester

This code describes a condition where the fetal membranes (chorion and amnion) fold back on themselves around the edges of the placenta, forming a thick, raised ring. This abnormal placental morphology can lead to various obstetric complications.

Use this code when documentation confirms the presence of a circumvallate placenta without specifying the trimester of pregnancy. This diagnosis is typically made during ultrasound examination or upon gross examination of the placenta after delivery.

• Ensure documentation explicitly states "circumvallate placenta" and does not specify a trimester.
• If the trimester is documented, use the more specific O43.11- codes (e.g., O43.111, O43.112, O43.113).
• Code any associated maternal or fetal complications separately, such as preterm labor, placental abruption, or fetal growth restriction.