O02.1
Missed abortion
O02.1 (also written O021) is a billable ICD-10-CM diagnosis code for missed abortion. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 5 codes in category O02 (Other abnormal products of conception). The Alphabetic Index lists it under 12 entries. Its coding notes include a Use additional code instruction, 11 Excludes1 entries and 4 Excludes2 entries.
Guidelines tip
From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.
The trimester character comes from the provider's documentation for the current encounter. The unspecified trimester code should rarely be used.
Use additional code
Add the listed code as a secondary code, if known.
- code from category O08 to identify any associated complication.
Also from chapter/block level (1 note)
- code, if applicable, from category Z3A, Weeks of gestation, to identify the specific week of the pregnancy, if known.
Excludes1
Not coded here. The listed conditions generally should not be reported together.
- failed induced abortion (O07.-)
- fetal death (intrauterine) (late) (O36.4)
- missed abortion with blighted ovum (O02.0)
- missed abortion with hydatidiform mole (O01.-)
- missed abortion with nonhydatidiform (O02.0)
- missed abortion with other abnormal products of conception (O02.8-)
- missed delivery (O36.4)
- stillbirth (P95)
Also from chapter/block level (2 notes)
- supervision of normal pregnancy (Z34.-)
Excludes2
Not included here. Both codes may be reported if the patient has both conditions.
Also from chapter/block level (4 notes)
Care settings
How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.
Home Health Primary
Accepted as the primary (principal) diagnosis on a home health claim. The Home Health Grouper assigns it to the MMTA - Other clinical group.
Source: CMS Home Health Grouper Software v07.2.26, effective October 1, 2026Inclusion terms
Conditions classified to this code.
- Early fetal death, before completion of 20 weeks of gestation, with retention of dead fetus
Notes
Also from chapter/block level (6 notes)
- 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
Alphabetic Index terms
Terms the official Alphabetic Index lists for this code. 12 entries
- Abortion (complete) (spontaneous), missed
- Dead, fetus, retained (mother), early pregnancy
- Delivery (childbirth) (labor), complicated, by, fetal, death, early
- Delivery (childbirth) (labor), complicated, by, intrauterine fetal death, early
- Missed, abortion
- Pregnancy (single) (uterine), complicated by (care of) (management affected by), death of fetus (near term), early pregnancy
- Pregnancy (single) (uterine), complicated by (care of) (management affected by), fetal (maternal care for), death (near term), early pregnancy
- Pregnancy (single) (uterine), complicated by (care of) (management affected by), intrauterine fetal death (near term), early pregnancy
- Pregnancy (single) (uterine), complicated by (care of) (management affected by), missed, abortion
- Retention, dead, fetus (at or near term) (mother), early fetal death
- Retention, fetus, dead, early
- Retention, products of conception, early pregnancy (dead fetus)