O23.591 Infection of other part of genital tract in pregnancy, first trimester

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

Applies from O23 Infections of genitourinary tract in pregnancy

Excludes2 (not included here)

• gonococcal infections complicating pregnancy, childbirth and the puerperium (O98.2)
• infections with a predominantly sexual mode of transmission NOS complicating pregnancy, childbirth and the puerperium (O98.3)
• syphilis complicating pregnancy, childbirth and the puerperium (O98.1)
• tuberculosis of genitourinary system complicating pregnancy, childbirth and the puerperium (O98.0)
• venereal disease NOS complicating pregnancy, childbirth and the puerperium (O98.3)

Use additional code

• code to identify organism (B95.-, B96.-)

MS-DRG index

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

Approximate ICD-9-CM (GEMs)

• 646.61 Infections of genitourinary tract in pregnancy, delivered, with or without mention of antepartum condition (approximate)
• 646.63 Infections of genitourinary tract in pregnancy, 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 O23.591

Back-references to O23

• Type 2 Excludes: O99.8 Other specified diseases and conditions complicating pregnancy, childbirth and the puerperium ("genitourinary infections in pregnancy (O23.-)")

Nearby codes

• O23.521 Salpingo-oophoritis in pregnancy, first trimester
• O23.522 Salpingo-oophoritis in pregnancy, second trimester
• O23.523 Salpingo-oophoritis in pregnancy, third trimester
• O23.529 Salpingo-oophoritis in pregnancy, unspecified trimester
• O23.59 Infection of other part of genital tract in pregnancy
• O23.591 Infection of other part of genital tract in pregnancy, first trimester (this code)
• O23.592 Infection of other part of genital tract in pregnancy, second trimester
• O23.593 Infection of other part of genital tract in pregnancy, third trimester
• O23.599 Infection of other part of genital tract in pregnancy, unspecified trimester
• O23.9 Unspecified genitourinary tract infection in pregnancy
• O23.90 Unspecified genitourinary tract infection in pregnancy, unspecified trimester