O36.8321 vs O36.8322
O36.8321 (Maternal care for abnormalities of the fetal heart rate or rhythm, second trimester, fetus 1) compared with O36.8322 (Maternal care for abnormalities of the fetal heart rate or rhythm, second trimester, fetus 2), from the official CMS tabular data.
Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources
Summary
No tabular note links these codes. Both belong to category O36, and nothing in the tabular list prevents reporting each when it is documented.
Registry fact- What is different?
Title wording.The titles differ in one word, “1” (O36.8321) versus “2” (O36.8322): O36.8321 is “Maternal care for abnormalities of the fetal heart rate or rhythm, second trimester, fetus 1”; O36.8322 is “Maternal care for abnormalities of the fetal heart rate or rhythm, second trimester, fetus 2”.
Registry fact
- Can these codes be reported together?
No instruction prevents it.No note in either entry names the other. Both belong to category O36; each may be reported when its own documentation is present.
Registry fact
- Is there an Excludes1 relationship?
None.Neither entry carries an Excludes1 note that names the other code. O36.8321 carries 2 Excludes1 notes and O36.8322 carries 2 Excludes1 notes covering other codes; the side-by-side table quotes them.
Official rule
- Is there an Excludes2 relationship?
None.Neither entry carries an Excludes2 note that names the other code. O36.8321 carries 1 Excludes2 note and O36.8322 carries 1 Excludes2 note covering other codes; the side-by-side table quotes them.
Official rule
- Is one more specific?
No.Neither is a subdivision of the other, and neither title is the unspecified form; they describe different conditions within category O36.
Registry fact
- Is one a parent or header code?
No.Both are billable codes, and neither contains the other.
Registry fact
- Are there sequencing instructions?
None.Neither entry carries a Code First or Use Additional Code note that names the other.
Official rule
- Are there other coding relationships?
None found.No laterality, encounter-phase, Table of Neoplasms, Table of Drugs and Chemicals, or history-versus-active-disease relationship links these codes.
MedCoder-derived
Official rule: a tabular instructional note or a section of the ICD-10-CM Official Guidelines, quoted as published. Registry fact: the codes’ own published attributes (titles, billable status, position in the hierarchy, code set). MedCoder-derived: a reading MedCoder computes from those facts; it is not itself a rule. How to read the labels
Can these codes be reported together?
Yes, when each is documented. O36.8321 and O36.8322 both belong to category O36.
No Excludes1/Excludes2 relationship exists between these codes in the official tabular list. The code titles state what each one covers, and the documentation decides which applies.
Side by side
Similar descriptions do not make codes interchangeable. The documentation and the official instructions decide which code applies.
Maternal care for abnormalities of the fetal heart rate or rhythm, second trimester, fetus 1
Maternal care for abnormalities of the fetal heart rate or rhythm, second trimester, fetus 2
- encounter for suspected maternal and fetal conditions ruled out (Z03.7-)
- placental transfusion syndromes (O43.0-)
- labor and delivery complicated by fetal stress (O77.-)
O36 Maternal care for other fetal problems
O00-O9A — Pregnancy, Childbirth and the Puerperium (O00-O9A)
- the listed conditions in the fetus as a reason for hospitalization or other obstetric care of the mother, or for termination of pregnancy
- One of the following 7th characters is to be assigned to each code under category O36. 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 O36 that has a 7th character of 1 through 9.
No Code first, Use additional code and Code also note at either code.
Notes are the code’s own tabular entry, quoted as published. A note that names the other code is the one the verdict above rests on. In a row that differs, notes every code shares are dimmed.
Derived from the official CMS ICD-10-CM tabular data (FY2027). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources