Chorioamnionitis, first trimester, fetus 5

This code describes an inflammatory condition of the fetal membranes (chorion and amnion) and amniotic fluid occurring during the first trimester of pregnancy, specifically affecting the fifth fetus in a multiple gestation. It is typically caused by bacterial infection ascending from the vagina or cervix.

Apply this code when documentation confirms chorioamnionitis in a pregnant patient during her first trimester, and it is explicitly noted as affecting the fifth fetus in a multifetal pregnancy. Supporting documentation includes clinical signs of infection (e.g., fever, uterine tenderness, foul-smelling amniotic fluid), laboratory findings (e.g., elevated white blood cell count), and ultrasound findings.

• Ensure the documentation clearly specifies "first trimester" and identifies the affected fetus as the "fifth."
• Do not confuse with chorioamnionitis occurring in later trimesters (O41.12x codes with different last digits).
• Always sequence this code after the primary obstetric complication code, if applicable, and consider additional codes for the infectious agent if identified.