O40.2 vs O40.2XX1
O40.2 (Polyhydramnios, second trimester) compared with O40.2XX1 (Polyhydramnios, second trimester, fetus 1), from the official CMS tabular data.
Summary
These codes represent different levels of the same hierarchy: O40.2 is the non-billable header that contains O40.2XX1, so only O40.2XX1 (or a sibling) is reported.
Registry fact- What is different?
Title wording and billing status.O40.2XX1’s title adds “fetus 1” to the wording the two share (“Polyhydramnios, second trimester”). O40.2 is a non-billable header; O40.2XX1 is billable.
Registry fact
- Can these codes be reported together?
Not as a pair.O40.2 is the non-billable header that contains O40.2XX1. A header is not reported on a claim, so the choice is O40.2XX1 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. O40.2 carries 1 Excludes1 note and O40.2XX1 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.O40.2XX1 is a subdivision of O40.2 in the tabular hierarchy, so it is the more specific of the two.
Registry fact
- Is one a parent or header code?
Yes.O40.2 is the non-billable header that contains O40.2XX1. 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 — O40.2 is not reportable. O40.2 is the non-billable category that contains O40.2XX1.
A header stands for the whole family of codes beneath it and is not reported on a claim, so the choice is O40.2XX1 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: O40.2 and O40.2XX1
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
| O40.2Polyhydramnios, second trimester | O40.2XX1Polyhydramnios, second trimester, fetus 1 | |
|---|---|---|
| Billing status | Non-billable header Report instead: O40.2XX0, O40.2XX1, O40.2XX2, O40.2XX3, O40.2XX4 | Billable |
| Classification | O00-O9A — Pregnancy, Childbirth and the Puerperium (O00-O9A) | O00-O9A — Pregnancy, Childbirth and the Puerperium (O00-O9A) |
| Definition | Polyhydramnios, second trimester is a non-billable ICD-10-CM category code (O40.2). | Polyhydramnios, second trimester, fetus 1 is a billable ICD-10-CM diagnosis code (O40.2XX1). |
| 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