Placenta increta, third trimester

This code signifies a severe obstetric complication where the placental villi invade the myometrium, but do not penetrate the uterine serosa, occurring during the third trimester of pregnancy. This condition is a form of abnormally invasive placenta, characterized by the absence of a decidual layer between the placenta and the uterine wall.

Assign this code when documentation explicitly states "placenta increta" and specifies the "third trimester." This diagnosis is typically made via ultrasound, MRI, or confirmed pathologically after delivery. Supporting documentation should include imaging reports and physician notes detailing the depth of placental invasion.

• Differentiate from placenta accreta (invasion to the myometrium) and percreta (invasion through the serosa).
• Ensure the trimester is clearly documented; other codes exist for different trimesters.
• Always sequence this code as a secondary diagnosis following the primary reason for the encounter, such as routine pregnancy care or complications of pregnancy.