Chorioamnionitis, unspecified trimester, fetus 4

This code signifies an infection of the chorion and amnion (the membranes surrounding the fetus) and the amniotic fluid, occurring at an unspecified point during the pregnancy. It specifically identifies this condition as affecting the fourth fetus in a multiple gestation.

Apply this code when documentation confirms chorioamnionitis in a multifetal pregnancy, and the specific trimester of onset is not documented. This code is appropriate when the medical record clearly identifies the affected fetus as the fourth in the sequence.

• Ensure documentation specifies "unspecified trimester" and clearly identifies the fourth fetus.
• Do not use this code if the trimester of chorioamnionitis onset is known; instead, use the trimester-specific codes (O41.121-O41.123).
• Always sequence this code after the primary obstetric code indicating the reason for the encounter, if applicable.