In simple words: This code indicates an ongoing pregnancy after a procedure to reduce the number of fetuses, specifically for fetus 1, at an unspecified trimester.

Continuing pregnancy after elective fetal reduction of one fetus or more, unspecified trimester, fetus 1.

Example 1: A pregnant woman carrying triplets undergoes an elective fetal reduction at 18 weeks (second trimester) to reduce the number of fetuses to twins.The code O31.30X1 is used to document the continuing pregnancy for the first remaining fetus. An additional code from category Z3A would be used to specify the current gestational week., A woman pregnant with quadruplets undergoes a fetal reduction procedure in her first trimester. The code O31.30X1 is used to indicate the ongoing pregnancy with the remaining fetuses.The specific week of gestation would also be coded with a Z3A code., A patient chooses to undergo multifetal pregnancy reduction in her third trimester due to complications. Following a successful reduction from twins to a singleton, O31.30X1 would be used in conjunction with a Z3A code.

Documentation should include details of the fetal reduction procedure, the number of fetuses reduced, the current gestational age, and the status of the remaining fetus/fetuses. The trimester of the fetal reduction should be documented.

** Code O31.30X1 is used specifically for the first remaining fetus after a reduction. If the patient is pregnant with twins following a reduction, codes O31.30X1 and O31.30X2 would be utilized. This code should be used in conjunction with a code from category Z3A to specify the gestational week if known.