O30.021 Conjoined twin pregnancy, first trimester

Billable ICD-10-CM code, FY2026.

Applies from O30 Multiple gestation

Code also

• any complications specific to multiple gestation

MS-DRG index

Defines the logic of DRG(s) 817-819 in MDC 14.

Approximate ICD-9-CM (GEMs)

• 678.11 Fetal conjoined twins, delivered, with or without mention of antepartum condition (approximate)
• 678.13 Fetal conjoined twins, antepartum condition or complication (approximate)

Medicare Code Edits (MCE v43.1 (April 2026))

• Maternity diagnoses (age 9 through 64): Age conflict edit. These diagnoses are clinically expected only in patients age 9 through 64.

Code annotations containing back-references to O30.021

Back-references to O30.02

• Type 1 Excludes: O30.01 Twin pregnancy, monochorionic/monoamniotic ("conjoined twins (O30.02-)")

Nearby codes

• O30.011 Twin pregnancy, monochorionic/monoamniotic, first trimester
• O30.012 Twin pregnancy, monochorionic/monoamniotic, second trimester
• O30.013 Twin pregnancy, monochorionic/monoamniotic, third trimester
• O30.019 Twin pregnancy, monochorionic/monoamniotic, unspecified trimester
• O30.02 Conjoined twin pregnancy
• O30.021 Conjoined twin pregnancy, first trimester (this code)
• O30.022 Conjoined twin pregnancy, second trimester
• O30.023 Conjoined twin pregnancy, third trimester
• O30.029 Conjoined twin pregnancy, unspecified trimester
• O30.03 Twin pregnancy, monochorionic/diamniotic
• O30.031 Twin pregnancy, monochorionic/diamniotic, first trimester