O40 vs O40.1XX0
O40 (Polyhydramnios) compared with O40.1XX0 (Polyhydramnios, first trimester, not applicable or unspecified), from the official CMS tabular data.
Summary
These codes represent different levels of the same hierarchy: O40 is the non-billable header that contains O40.1XX0, so only O40.1XX0 (or a sibling) is reported.
Registry fact- What is different?
The conditions named and billing status.O40 is “Polyhydramnios”; O40.1XX0 is “Polyhydramnios, first trimester, not applicable or unspecified”. O40 is a non-billable header; O40.1XX0 is billable.
Registry fact
- Can these codes be reported together?
Not as a pair.O40 is the non-billable header that contains O40.1XX0. A header is not reported on a claim, so the choice is O40.1XX0 or a sibling that matches the documentation.
Registry fact
- Is there an Excludes1 relationship?
None.Neither entry carries an Excludes1 note that names the other code. O40 carries 1 Excludes1 note and O40.1XX0 carries 1 Excludes1 note 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.
Official rule
- Is one more specific?
Yes.O40.1XX0 is a subdivision of O40 in the tabular hierarchy, so it is the more specific of the two.
Registry fact
- Is one a parent or header code?
Yes.O40 is the non-billable header that contains O40.1XX0. A header stands for the whole family beneath it and is not reported on a claim.
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?
Not as a pair — O40 is not reportable. O40 is the non-billable category that contains O40.1XX0.
A header stands for the whole family of codes beneath it and is not reported on a claim, so the choice is O40.1XX0 or a sibling that matches the documentation. No Excludes1/Excludes2 relationship exists between these codes in the official tabular list.
Official guidance behind these answers
Section I.B.2 — Level of Detail in Coding · applies to: O40 and O40.1XX0
Diagnosis codes are to be used and reported at their highest number of characters available and to the highest level of specificity documented in the medical record. ICD-10-CM diagnosis codes are composed of codes with 3, 4, 5, 6 or 7 characters. Codes with three characters are included in ICD-10-CM as the heading of a category of codes that may be further subdivided by the use of fourth and/or fifth characters and/or sixth characters, which provide greater detail. A three-character code is to be used only if it is not further subdivided. A code is invalid if it has not been coded to the full number of characters required for that code, including the 7th character, if applicable.
ICD-10-CM Official Guidelines FY2026
Quoted from the ICD-10-CM Official Guidelines for Coding and Reporting in effect for the release shown. The tabular notes above are the code-level instruction; these sections are the convention that says how such a note is applied. Source document (CMS PDF) · Release and checksum
Side by side
| O40Polyhydramnios | O40.1XX0Polyhydramnios, first trimester, not applicable or unspecified | |
|---|---|---|
| Billing status | Non-billable header Report instead: O40.1XX0, O40.1XX1, O40.1XX2, O40.1XX3, O40.1XX4 | Billable |
| Classification | O00-O9A — Pregnancy, Childbirth and the Puerperium (O00-O9A) | O00-O9A — Pregnancy, Childbirth and the Puerperium (O00-O9A) |
| Definition | Polyhydramnios is a non-billable ICD-10-CM category code (O40). | Polyhydramnios, first trimester, not applicable or unspecified is a billable ICD-10-CM diagnosis code (O40.1XX0). |
| 7th character | One of the following 7th characters is to be assigned to each code under category O40. 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 O40 that has a 7th character of 1 through 9. | One of the following 7th characters is to be assigned to each code under category O40. 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 O40 that has a 7th character of 1 through 9. |
| Includes | hydramnios | hydramnios |
| Excludes1 | encounter for suspected maternal and fetal conditions ruled out (Z03.7-) | encounter for suspected maternal and fetal conditions ruled out (Z03.7-) |
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.
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