O98.311 Other infections with a predominantly sexual mode of transmission complicating pregnancy, first trimester

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

Applies from O98 Maternal infectious and parasitic diseases classifiable elsewhere but complicating pregnancy, childbirth and the puerperium

Includes

• the listed conditions when complicating the pregnant state, when aggravated by the pregnancy, or as a reason for obstetric care

Excludes2 (not included here)

• herpes gestationis (O26.4-)
• infectious carrier state (O99.82-, O99.83-)
• obstetrical tetanus (A34)
• puerperal infection (O86.-)
• puerperal sepsis (O85)
• when the reason for maternal care is that the disease is known or suspected to have affected the fetus (O35-O36)

Use additional code

• code (Chapter 1), to identify specific infectious or parasitic disease

Applies from O98.3 Other infections with a predominantly sexual mode of transmission complicating pregnancy, childbirth and the puerperium

Applicable to

• Conditions in A55-A64

MS-DRG index

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

Approximate ICD-9-CM (GEMs)

• 647.21 Other venereal diseases of mother, complicating pregnancy, childbirth, or the puerperium, delivered, with or without mention of antepartum condition (approximate)
• 647.23 Other venereal diseases of mother, complicating pregnancy, childbirth, or 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 O98.311

Back-references to O98.3

• Type 2 Excludes: O23 Infections of genitourinary tract in pregnancy ("infections with a predominantly sexual mode of transmission NOS complicating pregnancy, childbirth and the puerperium (O98.3)")
• Type 2 Excludes: O23 Infections of genitourinary tract in pregnancy ("venereal disease NOS complicating pregnancy, childbirth and the puerperium (O98.3)")

Nearby codes

• O98.219 Gonorrhea complicating pregnancy, unspecified trimester
• O98.22 Gonorrhea complicating childbirth
• O98.23 Gonorrhea complicating the puerperium
• O98.3 Other infections with a predominantly sexual mode of transmission complicating pregnancy, childbirth and the puerperium
• O98.31 Other infections with a predominantly sexual mode of transmission complicating pregnancy
• O98.311 Other infections with a predominantly sexual mode of transmission complicating pregnancy, first trimester (this code)
• O98.312 Other infections with a predominantly sexual mode of transmission complicating pregnancy, second trimester
• O98.313 Other infections with a predominantly sexual mode of transmission complicating pregnancy, third trimester
• O98.319 Other infections with a predominantly sexual mode of transmission complicating pregnancy, unspecified trimester
• O98.32 Other infections with a predominantly sexual mode of transmission complicating childbirth
• O98.33 Other infections with a predominantly sexual mode of transmission complicating the puerperium