Chorioamnionitis, first trimester, other fetus

This code signifies an inflammatory condition of the fetal membranes (chorion and amnion) and amniotic fluid occurring in the first trimester of pregnancy, specifically affecting one of multiple fetuses. It indicates an infection of the sac surrounding the developing fetus, which can lead to various complications.

Use this code when documentation clearly indicates chorioamnionitis diagnosed in the first trimester (up to 13 weeks and 6 days gestation) in a multifetal pregnancy, and the condition is specified as affecting a fetus other than the one designated as the primary or index fetus. Supporting documentation would include ultrasound findings, amniocentesis results, or clinical signs of infection in the context of a multifetal pregnancy.

• Ensure the documentation specifies "first trimester" and "other fetus" in a multifetal gestation to accurately assign this code.
• Distinguish from O41.1210 (unspecified fetus) and O41.1211 (first fetus) when coding multifetal pregnancies.
• Always sequence this code after the primary obstetric code indicating the pregnancy itself (e.g., O30.0- for twin pregnancy).