O12.21 Gestational edema with proteinuria, first trimester

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

MS-DRG index

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

Approximate ICD-9-CM (GEMs)

• 646.11 Edema or excessive weight gain in pregnancy, without mention of hypertension, delivered, with or without mention of antepartum complication (approximate)
• 646.13 Edema or excessive weight gain in pregnancy, without mention of hypertension, antepartum condition or complication (approximate)
• 646.21 Unspecified renal disease in pregnancy, without mention of hypertension, delivered, with or without mention of antepartum condition (approximate)
• 646.23 Unspecified renal disease in pregnancy, without mention of hypertension, 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 O12.21

Back-references to O12.2

• Type 2 Excludes: O26.0 Excessive weight gain in pregnancy ("gestational edema (O12.0, O12.2)")

Back-references to O12

• Type 2 Excludes: O99.4 Diseases of the circulatory system complicating pregnancy, childbirth and the puerperium ("hypertensive disorders (O10-O16)")

Nearby codes

• O12.13 Gestational proteinuria, third trimester
• O12.14 Gestational proteinuria, complicating childbirth
• O12.15 Gestational proteinuria, complicating the puerperium
• O12.2 Gestational edema with proteinuria
• O12.20 Gestational edema with proteinuria, unspecified trimester
• O12.21 Gestational edema with proteinuria, first trimester (this code)
• O12.22 Gestational edema with proteinuria, second trimester
• O12.23 Gestational edema with proteinuria, third trimester
• O12.24 Gestational edema with proteinuria, complicating childbirth
• O12.25 Gestational edema with proteinuria, complicating the puerperium