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O31.40 ICD-10-CM Code: Continuing pregnancy after vanishing twin syndrome of one fetus or more, unspecified trimester

Compare with another code for O31.40Check this code on a claim

Billing Status: NO. This is a non-billable ICD-10-CM code: report a more specific billable code beneath it.

Coding at a Glance

7th character
Required — see the character table on this page
Tabular directives
3 Excludes2

Not billable · FY2027A non-billable heading in the tabular list: report a more specific code beneath it.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too, and is marked with where it comes from.

7th character:required: report a code with a 7th character· One of the following 7th characters is to be assigned to each code under category O31. 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 O31 that has a 7th character of 1 through 9.See the 7th character note

Excludes2from O31Not included here; may be reported together
  • delayed delivery of second twin, triplet, etc. (O63.2)
  • malpresentation of one fetus or more (O32.9)
  • placental transfusion syndromes (O43.0-)

Where it sits Source: CMS/NCHS

Under:Chapter 15: Pregnancy, Childbirth and the PuerperiumO30-O48 Maternal care related to the fetus and amniotic cavity and possible delivery problemsO31 Complications specific to multiple gestationO31.4 Continuing pregnancy after vanishing twin syndrome of one fetus or more

Codes under O31.40 (7)

  • O31.40X0Continuing pregnancy after vanishing twin syndrome of one fetus or more, unspecified trimester, not applicable or unspecifiedBillable
  • O31.40X1Continuing pregnancy after vanishing twin syndrome of one fetus or more, unspecified trimester, fetus 1Billable
  • O31.40X2Continuing pregnancy after vanishing twin syndrome of one fetus or more, unspecified trimester, fetus 2Billable
  • O31.40X3Continuing pregnancy after vanishing twin syndrome of one fetus or more, unspecified trimester, fetus 3Billable
  • O31.40X4Continuing pregnancy after vanishing twin syndrome of one fetus or more, unspecified trimester, fetus 4Billable
  • O31.40X5Continuing pregnancy after vanishing twin syndrome of one fetus or more, unspecified trimester, fetus 5Billable
  • O31.40X9Continuing pregnancy after vanishing twin syndrome of one fetus or more, unspecified trimester, other fetusBillable

Most relevant related codes MedCoder-derived

Read off the official notes above and this code’s own position in the tabular list. Which to report is a documentation question; Compare shows the two side by side.

CompareCheck ClaimView Related Codes

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for O31.40 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on O31.40 itself; “inherited from” names the category or block whose note applies here.

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Source: inherited from O31

7th Character Guide

"One of the following 7th characters is to be assigned to each code under category O31. 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 O31 that has a 7th character of 1 through 9."

  • 0 — not applicable or unspecified
  • 1 — fetus 1
  • 2 — fetus 2
  • 3 — fetus 3
  • 4 — fetus 4
  • 5 — fetus 5
  • 9 — other fetus

Variant codes in this family

O31.40X0, O31.40X1, O31.40X2, O31.40X3, O31.40X4, O31.40X5, O31.40X9

Character meanings are CMS's official 7th-character extensions for this family, as carried in each variant code's official description; variant codes are registry rows. The explanation of how the encounter character is assigned is MedCoder editorial, distinct from the official content above it.

Coder workflow for O31.40

MedCoder structured workflow — derived from this code’s own official record

Before you code O31.40

  1. O31.40 is not reportable as written. Select the more specific code beneath it that the documentation supports. Codes are reported to the highest level of specificity the classification provides (Guidelines I.B.2).

    ReviewO31.40X0, O31.40X1, O31.40X2, O31.40X3, O31.40X4, O31.40X5, O31.40X9

    See the relationships section · Guide: How to choose an ICD-10-CM code →

  2. A 7th character is required in this family. Confirm the documentation supports the character assigned — its meaning in this family is defined in the official instruction. O31.40 is not valid without one. The official 7th-character definitions for this family are quoted in the guide.

    See the 7th Character Guide

  3. Confirm the condition is documented as complicating the pregnancy, childbirth, or the puerperium, and check the trimester where the code carries one and the fetus character where the category requires it. Chapter 15 codes belong on the maternal record only and take sequencing priority over codes from other chapters. It is the provider’s responsibility to state that a condition is not affecting the pregnancy; the trimester is assigned from the documentation (Guidelines I.C.15.a, I.C.15.a.1, I.C.15.a.3).

    Guide: How to choose an ICD-10-CM code →

Choose the right path

  1. Does the documentation support one of the more specific codes beneath O31.40?
    Yes → Select that code and continue the checks below on its own page.
    No → O31.40 cannot be reported as written. Where the codes beneath it include an unspecified code, that code applies when the record goes no further; otherwise query for the missing detail.

    ReviewO31.40X0, O31.40X1, O31.40X2, O31.40X3, O31.40X4, O31.40X5, O31.40X9

  2. Does the documentation support one of this family’s 7th-character values?
    Yes → Assign the matching 7th character; the variant codes are in the 7th Character Guide.
    No → The code is invalid without its 7th character — query for the missing element.

Report the code beneath O31.40 that the documentation supports, not O31.40 itself. Then confirm that code is valid for the date of service on its own page.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
7th-character basis
The documented element this family’s 7th character records (see the official definitions in the 7th Character Guide).
Trimester
Assigned from the documented trimester at the encounter, or the trimester in which the condition developed for inpatient stays (Guidelines I.C.15.a.3).
Fetus affected
For multiple gestations, the fetus the condition affects, as documented.
Any detail beyond this code’s title
What the record states that a more specific code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

  • Excludes2 — not part of O31.40(3 notes)

    Coding workflow: The conditions named in this note are not included in O31.40. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareO63.2, O32.9, O43.0

    See the official tabular notes · Guidelines I.A.12.b

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: The provider documents the condition in the terms of this code’s title and records no further detail.

Coding question: Is a more specific sibling code supportable?

Path: Review the specific siblings in this subcategory and what each requires the record to state.

Reason: A more specific code needs documentation of the distinguishing element; without it the unspecified code is appropriate, and a provider query is the route to specificity (Guidelines I.A.9.b, I.B.18).

ReviewO31.41, O31.42

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Don’t confuse O31.40 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of O31.40 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

  • O31.40X0— Encounter relationship (Review)

    Same underlying diagnosis, different encounter phase.

    The same diagnosis at a different phase of care; one encounter takes one 7th character.

    What moves you there: Documentation of a not applicable or unspecified moves the case to O31.40X0.

    Full comparison: O31.40 vs O31.40X0 →

  • O31.40X1— Encounter relationship (Review)

    Same underlying diagnosis, different encounter phase.

    The same diagnosis at a different phase of care; one encounter takes one 7th character.

    What moves you there: Documentation of a fetus 1 moves the case to O31.40X1.

    Full comparison: O31.40 vs O31.40X1 →

  • O63.2— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of delayed delivery of second twin, triplet, etc. adds O63.2; it is not part of this code and both may be reported when both are documented.

    Full comparison: O31.40 vs O63.2 →

  • O32.9— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of malpresentation of one fetus or more adds O32.9; it is not part of this code and both may be reported when both are documented.

    Full comparison: O31.40 vs O32.9 →

  • O43.0— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of placental transfusion syndromes adds O43.0; it is not part of this code and both may be reported when both are documented.

    Full comparison: O31.40 vs O43.0 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Continuing pregnancy after vanishing twin syndrome of one fetus or more, unspecified trimester is a non-billable ICD-10-CM category code (O31.40). A more specific billable subcode must be selected for claims submission.

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Verify Before Coding

  • Not billable as written — a more specific code is required: O31.40X0, O31.40X1, O31.40X2, O31.40X3, O31.40X4.
  • Requires a 7th character. "One of the following 7th characters is to be assigned to each code under category O31. 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 O31 that has a 7th character of 1 through 9." Options: O31.40X0, O31.40X1, O31.40X2, O31.40X3, O31.40X4, O31.40X5

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name O31.40 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 10 Excludes2 notes: O20 — Hemorrhage in early pregnancy (via O31.-), O20-O29 — Other maternal disorders predominantly related to pregnancy (O20-O29) (via O31.-), O21 — Excessive vomiting in pregnancy (via O31.-), O22 — Venous complications and hemorrhoids in pregnancy (via O31.-), O23 — Infections of genitourinary tract in pregnancy (via O31.-), O24 — Diabetes mellitus in pregnancy, childbirth, and the puerperium (via O31.-), O25 — Malnutrition in pregnancy, childbirth and the puerperium (via O31.-), O26 — Maternal care for other conditions predominantly related to pregnancy (via O31.-), O28 — Abnormal findings on antenatal screening of mother (via O31.-), O29 — Complications of anesthesia during pregnancy (via O31.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

Contextual Map

Every relationship of O31.40 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run O31.40 with these 8 related codes in Claim Check

Hierarchy

Referenced by Excludes2 notes (10)

Nearest codes (40)

Change history

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Common coding questions

MedCoder editorial

Can O31.40 be billed directly?

No. O31.40 (Continuing pregnancy after vanishing twin syndrome of one fetus or more, unspecified trimester) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.

Does O31.40 require a 7th character?

Yes. One of the following 7th characters is to be assigned to each code under category O31. 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 O31 that has a 7th character of 1 through 9..

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder-derived relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder editorial explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

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

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "O31.40 — Continuing pregnancy after vanishing twin syndrome of one fetus or more, unspecified trimester." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/o31.40-continuing-pregnancy-after-vanishing-twin-syndrome-of-one-fetus-or-more-unspecified-trimester

Change history

Changed in FY2027, the release in force: Added to the code set.

  • FY2027 — October 1, 2026
    Added to the code set
    Continuing pregnancy after vanishing twin syndrome of one fetus or more, unspecified trimester
    FY2027 changes

Nearest Codes in This Family

Official ICD-10-CM classifications closest to O31.40 in its code family, with their registry titles.

View all codes in the O31 family