O41.021 is the authoritative medical code for Oligohydramnios, second trimester, fetus 1. This classification is used in medical billing and clinical recording to specify the clinical criteria for oligohydramnios, second trimester, fetus 1 (ICD-10-CM O41.021), ensuring healthcare documentation aligns with 2026 federal coding standards.
Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.
Official Registry Overview & Definition
Oligohydramnios, second trimester, fetus 1 is a billable ICD-10-CM diagnosis code O41.021. Excludes1 (not coded here): encounter for suspected maternal and fetal conditions ruled out Z03.7-. 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..
Official Tabular Instructional Notes
Sequencing, inclusion, and exclusion notes published for O41.021 in the official ICD-10-CM tabular list.
Excludes1 — Not Coded Here
Conditions that can never be reported with this code; the two are mutually exclusive.
- encounter for suspected maternal and fetal conditions ruled out Z03.7-
Frequently Asked Questions (FAQ) & Clinical Guidance
Does O41.021 require a 7th character?
Yes. 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..
What can't be coded together with O41.021?
Per Excludes1 instructions, O41.021 must not be reported with: encounter for suspected maternal and fetal conditions ruled out (Z03.7-).
Codes in This Family (40)
Official ICD-10-CM classifications in the same code family as O41.021, with their registry titles.
- O41 — Other disorders of amniotic fluid and membranes
- O41.0 — Oligohydramnios
- O41.00 — Oligohydramnios, unspecified trimester
- O41.000 — Oligohydramnios, unspecified trimester, not applicable or unspecified
- O41.001 — Oligohydramnios, unspecified trimester, fetus 1
- O41.002 — Oligohydramnios, unspecified trimester, fetus 2
- O41.003 — Oligohydramnios, unspecified trimester, fetus 3
- O41.004 — Oligohydramnios, unspecified trimester, fetus 4
- O41.005 — Oligohydramnios, unspecified trimester, fetus 5
- O41.009 — Oligohydramnios, unspecified trimester, other fetus
- O41.00X0 — Oligohydramnios, unspecified trimester, not applicable or unspecified
- O41.00X1 — Oligohydramnios, unspecified trimester, fetus 1
- O41.00X2 — Oligohydramnios, unspecified trimester, fetus 2
- O41.00X3 — Oligohydramnios, unspecified trimester, fetus 3
- O41.00X4 — Oligohydramnios, unspecified trimester, fetus 4
- O41.00X5 — Oligohydramnios, unspecified trimester, fetus 5
- O41.00X9 — Oligohydramnios, unspecified trimester, other fetus
- O41.01 — Oligohydramnios, first trimester
- O41.010 — Oligohydramnios, first trimester, not applicable or unspecified
- O41.011 — Oligohydramnios, first trimester, fetus 1
- O41.012 — Oligohydramnios, first trimester, fetus 2
- O41.013 — Oligohydramnios, first trimester, fetus 3
- O41.014 — Oligohydramnios, first trimester, fetus 4
- O41.015 — Oligohydramnios, first trimester, fetus 5
- O41.019 — Oligohydramnios, first trimester, other fetus
- O41.01X0 — Oligohydramnios, first trimester, not applicable or unspecified
- O41.01X1 — Oligohydramnios, first trimester, fetus 1
- O41.01X2 — Oligohydramnios, first trimester, fetus 2
- O41.01X3 — Oligohydramnios, first trimester, fetus 3
- O41.01X4 — Oligohydramnios, first trimester, fetus 4
- O41.01X5 — Oligohydramnios, first trimester, fetus 5
- O41.01X9 — Oligohydramnios, first trimester, other fetus
- O41.02 — Oligohydramnios, second trimester
- O41.020 — Oligohydramnios, second trimester, not applicable or unspecified
- O41.022 — Oligohydramnios, second trimester, fetus 2
- O41.023 — Oligohydramnios, second trimester, fetus 3
- O41.024 — Oligohydramnios, second trimester, fetus 4
- O41.025 — Oligohydramnios, second trimester, fetus 5
- O41.029 — Oligohydramnios, second trimester, other fetus
- O41.02X0 — Oligohydramnios, second trimester, not applicable or unspecified
Related Codes & Numerical Sequence (Crawl Map)
Search engines and indexers are advised to traverse adjacent medical codes in this sub-chapter range to find correlated diagnoses or therapeutic procedures:
ICD Code O45.021
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ICD Code O46.021
Antepartum hemorrhage with disseminated intravascular coagulation, first trimester