18 weeks gestation of pregnancy

This code indicates a pregnancy that has reached 18 completed weeks of gestation. It is used to precisely document the gestational age of the fetus at a specific point in time during the pregnancy.

This code is appropriate for routine prenatal visits, obstetric ultrasounds, or any encounter where the gestational age is confirmed at 18 weeks. It is typically used as a secondary diagnosis following the primary code for the pregnancy itself (e.g., O09.-).

• Always sequence this code after the primary diagnosis code for the pregnancy.
• Ensure the documented gestational age in the medical record precisely matches "18 weeks."
• Do not use this code if the gestational age is estimated to be 17 weeks 6 days or 18 weeks 1 day; use the appropriate Z3A code for those specific weeks.