2027 ICD-10-CM Diagnosis Code O98.911Unspecified maternal infectious and parasitic disease complicating pregnancy, first trimester
ICD-10-CM Codes›O00-O9A›O94-O9A›O98
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not Chronic
O98.911 is a billable ICD-10-CM diagnosis code for unspecified maternal infectious and parasitic disease complicating pregnancy, first trimester. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 817 through 819, 831 through 833. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 36 closely related codes. The code is restricted by the Medicare Code Editor to maternity cases (age 9 through 64). In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified complications in pregnancy.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for O98.911.
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to O98.911: its own notes plus those printed at O98 and Chapter 15. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- the listed conditions when complicating the pregnant state, when aggravated by the pregnancy, or as a reason for obstetric care
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- supervision of normal pregnancy (Z34.-)
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- code (Chapter 1), to identify specific infectious or parasitic disease
- code, if applicable, from category Z3A, Weeks of gestation, to identify the specific week of the pregnancy, if known.
Notes
General instructions on how these codes are used.
- CODES FROM THIS CHAPTER ARE FOR USE ONLY ON MATERNAL RECORDS, NEVER ON NEWBORN RECORDS
- Codes from this chapter are for use for conditions related to or aggravated by the pregnancy, childbirth, or by the puerperium (maternal causes or obstetric causes)
- Trimesters are counted from the first day of the last menstrual period. They are defined as follows:
- 1st trimester- less than 14 weeks 0 days
- 2nd trimester- 14 weeks 0 days to less than 28 weeks 0 days
- 3rd trimester- 28 weeks 0 days until delivery
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name O98.911, its category, or a range that includes it.
Excludes2 1
These codes carry an Excludes2 note naming O98.911: its condition is not part of those codes, and both may be reported when the patient has both.
- Chapter 1 (A00-B99) Certain infectious and parasitic diseasesinfectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-) names O98.-, which includes this code
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Infections and Pregnancy
During pregnancy, some common infections such as the common cold or a skin infection do not usually cause serious problems. Some infections, such as the flu, can be more severe when you're pregnant. But other infections can be harmful to you, your fetus, or both.
The full article covers:
- How can infections affect your pregnancy?
- What infections can be harmful during pregnancy?
- What are the symptoms of an infection during pregnancy?
- What are the treatments for infections during pregnancy?
- Can infections during pregnancy be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert O98.911 to ICD-9-CMHistory
Code HistoryHistory
Questions About O98.911Overview
Is O98.911 a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report unspecified maternal infectious and parasitic disease complicating pregnancy, first trimester on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does O98.911 group to?
When unspecified maternal infectious and parasitic disease complicating pregnancy, first trimester is the principal diagnosis on an inpatient stay, it groups to MS-DRG 833, 832, 831, 819, 818, 817, with relative weights from 0.5000 to 1.7586 depending on complications. Higher weights mean higher Medicare reimbursement.
Is O98.911 a CC or MCC?
CMS lists O98.911 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 36 closely related codes in its exclusion list.
Who can O98.911 be reported for?
The Medicare Code Editor checks unspecified maternal infectious and parasitic disease complicating pregnancy, first trimester against patient demographics: this code is intended for maternity cases (age 9 through 64). Claims outside these limits are flagged as inconsistent.
Does O98.911 need an additional code?
When the condition applies, yes. The Use Additional Code note at O98, which applies to O98.911, reads: code (Chapter 1), to identify specific infectious or parasitic disease. The additional code is reported after O98.911.
