O22.21 Superficial thrombophlebitis in pregnancy, first trimester

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

Applies from O22 Venous complications and hemorrhoids in pregnancy

Excludes1 (never code together)

• venous complications of:
• abortion NOS (O03.9)
• ectopic or molar pregnancy (O08.7)
• failed attempted abortion (O07.35)
• induced abortion (O04.85)
• spontaneous abortion (O03.89)

Excludes2 (not included here)

• obstetric pulmonary embolism (O88.-)
• venous complications and hemorrhoids of childbirth and the puerperium (O87.-)

Applies from O22.2 Superficial thrombophlebitis in pregnancy

Applicable to

• Phlebitis in pregnancy NOS
• Thrombophlebitis of legs in pregnancy
• Thrombosis in pregnancy NOS

Use additional code

• code to identify the superficial thrombophlebitis (I80.0-)

MS-DRG index

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

Approximate ICD-9-CM (GEMs)

• 671.21 Superficial thrombophlebitis complicating pregnancy and the puerperium, delivered, with or without mention of antepartum condition (approximate)
• 671.23 Superficial thrombophlebitis complicating pregnancy and the puerperium, 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 O22.21

Back-references to O22

• Code First: I80 Phlebitis and thrombophlebitis ("phlebitis and thrombophlebitis complicating pregnancy, childbirth and the puerperium (O22.-, O87.-)")
• Code First: I82 Other venous embolism and thrombosis ("pregnancy, childbirth and the puerperium (O22.-, O87.-)")
• Type 2 Excludes: O87 Venous complications and hemorrhoids in the puerperium ("venous complications in pregnancy (O22.-)")
• Type 2 Excludes: O99.4 Diseases of the circulatory system complicating pregnancy, childbirth and the puerperium ("venous complications and cerebrovenous sinus thrombosis in pregnancy (O22.-)")

Nearby codes

• O22.11 Genital varices in pregnancy, first trimester
• O22.12 Genital varices in pregnancy, second trimester
• O22.13 Genital varices in pregnancy, third trimester
• O22.2 Superficial thrombophlebitis in pregnancy
• O22.20 Superficial thrombophlebitis in pregnancy, unspecified trimester
• O22.21 Superficial thrombophlebitis in pregnancy, first trimester (this code)
• O22.22 Superficial thrombophlebitis in pregnancy, second trimester
• O22.23 Superficial thrombophlebitis in pregnancy, third trimester
• O22.3 Deep phlebothrombosis in pregnancy
• O22.30 Deep phlebothrombosis in pregnancy, unspecified trimester
• O22.31 Deep phlebothrombosis in pregnancy, first trimester