2021 ICD-10-CM Diagnosis Code O41.121

Chorioamnionitis, first trimester

    2016 2017 2018 2019 2020 2021 Non-Billable/Non-Specific Code 1st Trimester (< 14 weeks)
  • O41.121 should not be used for reimbursement purposes as there are multiple codes below it that contain a greater level of detail.
  • The 2021 edition of ICD-10-CM O41.121 became effective on October 1, 2020.
  • This is the American ICD-10-CM version of O41.121 - other international versions of ICD-10 O41.121 may differ.
ICD-10-CM Coding Rules
  • O41.121 is applicable to mothers in the first trimester of pregnancy, which is defined as less than 14 weeks since the first day of the last menstrual period.
The following code(s) above O41.121 contain annotation back-references
Annotation Back-References
In this context, annotation back-references refer to codes that contain:
  • Applicable To annotations, or
  • Code Also annotations, or
  • Code First annotations, or
  • Excludes1 annotations, or
  • Excludes2 annotations, or
  • Includes annotations, or
  • Note annotations, or
  • Use Additional annotations
that may be applicable to O41.121:
  • O00-O9A
    2021 ICD-10-CM Range O00-O9A

    Pregnancy, childbirth and the puerperium

    • 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
    Type 1 Excludes
    • supervision of normal pregnancy (Z34.-)
    Type 2 Excludes
    • 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
    • code from category Z3A, Weeks of gestation, to identify the specific week of the pregnancy, if known.
    Pregnancy, childbirth and the puerperium
  • O41
    ICD-10-CM Diagnosis Code O41

    Other disorders of amniotic fluid and membranes

      2016 2017 2018 2019 2020 2021 Non-Billable/Non-Specific Code
    Type 1 Excludes
    • encounter for suspected maternal and fetal conditions ruled out (Z03.7-)
    Other disorders of amniotic fluid and membranes
Code History
  • 2016 (effective 10/1/2015): New code (first year of non-draft ICD-10-CM)
  • 2017 (effective 10/1/2016): No change
  • 2018 (effective 10/1/2017): No change
  • 2019 (effective 10/1/2018): No change
  • 2020 (effective 10/1/2019): No change
  • 2021 (effective 10/1/2020): No change
ICD-10-CM Codes Adjacent To O41.121
O41.1039 …… other fetus
O41.109 Infection of amniotic sac and membranes, unspecified, unspecified trimester
O41.1090 …… not applicable or unspecified
O41.1091 …… fetus 1
O41.1092 …… fetus 2
O41.1093 …… fetus 3
O41.1094 …… fetus 4
O41.1095 …… fetus 5
O41.1099 …… other fetus
O41.12 Chorioamnionitis
O41.121 Chorioamnionitis, first trimester
O41.1210 …… not applicable or unspecified
O41.1211 …… fetus 1
O41.1212 …… fetus 2
O41.1213 …… fetus 3
O41.1214 …… fetus 4
O41.1215 …… fetus 5
O41.1219 …… other fetus
O41.122 Chorioamnionitis, second trimester
O41.1220 …… not applicable or unspecified
O41.1221 …… fetus 1

Reimbursement claims with a date of service on or after October 1, 2015 require the use of ICD-10-CM codes.