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O41.121Non-billableSave

O41.121 - Chorioamnionitis, first trimester

ICD-10-CM Chapter 15: Pregnancy, childbirth and the puerperium · O30-O48 Maternal care related to the fetus and amniotic cavity and possible delivery problems (O30-O48) · Subcategory of O41.12 · FY2027

Coding Guidance

O41.121 requires a 7th character. Report the code below that matches the documentation, for example 0 for not applicable or unspecified, 1 for fetus 1, 2 for fetus 2.

7th Character

One of the following 7th characters is to be assigned to each code under category O41. 7th character 0 is for single gestations and multiple gestations where the fetus is unspecified. 7th characters 1 through 9 are for cases of multiple gestations to identify the fetus for which the code applies. The appropriate code from category O30, Multiple gestation, must also be assigned when assigning a code from category O41 that has a 7th character of 1 through 9.

Includes, Excludes and Coding Notes

Excludes 1 — Not Coded HereFrom O41

Mutually exclusive: these conditions are never reported together with this code.

  • encounter for suspected maternal and fetal conditions ruled out (Z03.7-)
Excludes 1 — Not Coded HereFrom Chapter O00-O9A

Mutually exclusive: these conditions are never reported together with this code.

  • supervision of normal pregnancy (Z34.-)
Excludes 2 — Not Included HereFrom Chapter O00-O9A

Not part of this code; report both codes when the patient has both conditions.

  • mental and behavioral disorders associated with the puerperium (F53.-)
  • obstetrical tetanus (A34)
  • postpartum necrosis of pituitary gland (E23.0)
  • puerperal osteomalacia (M83.0)
Use Additional CodeFrom Chapter O00-O9A

Add a secondary code to identify the associated condition or cause when it is documented.

  • code, if applicable, from category Z3A, Weeks of gestation, to identify the specific week of the pregnancy, if known.
NotesFrom Chapter O00-O9A

Instructional notes from the ICD-10-CM tabular list.

  • 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

More Specific Codes (7)

O41.1210Chorioamnionitis, first trimester, not applicable or unspecified→O41.1211Chorioamnionitis, first trimester, fetus 1→O41.1212Chorioamnionitis, first trimester, fetus 2→O41.1213Chorioamnionitis, first trimester, fetus 3→O41.1214Chorioamnionitis, first trimester, fetus 4→O41.1215Chorioamnionitis, first trimester, fetus 5→O41.1219Chorioamnionitis, first trimester, other fetus→

Related condition guides

Documentation requirements, coding pitfalls and FAQs for conditions coded with O41.121.