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Q42.1 ICD-10-CM Code: Congenital absence, atresia and stenosis of rectum without fistula

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Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Official instructions
2 inclusion terms
Risk adjustment
CMS-HCC V28: 1 category

What these terms mean →

Billable · FY2027A valid, specific ICD-10-CM code, reportable for dates of service in FY2027.

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.

IncludesWhat this code covers
  • congenital obstruction, occlusion and stricture of large intestine (from Q42)
  • Imperforate rectum

Where it sits Source: CMS/NCHS

Under:Chapter 17: Congenital Malformations, Deformations and Chromosomal Abnormalities (Q00-QA1) (Q00-QA1)Q38-Q45 Other congenital malformations of the digestive systemQ42 Congenital absence, atresia and stenosis of large intestine

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Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v44, Appendix B.

  • MS-DRG 393 — OTHER DIGESTIVE SYSTEM DIAGNOSES WITH MCC (MDC 06)
  • MS-DRG 394 — OTHER DIGESTIVE SYSTEM DIAGNOSES WITH CC (MDC 06)
  • MS-DRG 395 — OTHER DIGESTIVE SYSTEM DIAGNOSES WITHOUT CC/MCC (MDC 06)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Risk Adjustment (CMS-HCC)

Payment categories this diagnosis maps to under CMS-HCC V28, payment year 2026.

  • HCC 78 — Intestinal Obstruction/Perforation

Risk scores depend on the enrollee's full accepted diagnosis set and segment; a category mapping alone does not determine payment.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for Q42.1 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 Q42.1 itself; “inherited from” names the category or block whose note applies here.

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

  • congenital obstruction, occlusion and stricture of large intestine

Source: inherited from Q42

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Imperforate rectum

Don’t confuse Q42.1 with…

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

The codes most likely to be picked instead of Q42.1 — 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.

  • Q42.9— Specificity relationship (Review)

    Overlapping diagnoses in the same category.

    Overlapping codes in the same category — the documentation decides which is the more specific fit.

    What moves you there: A record that documents no more than “Congenital absence, atresia and stenosis of large intestine, part unspecified” takes Q42.9; specificity in the record moves it back here.

    Full comparison: Q42.1 vs Q42.9 →

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

Congenital absence, atresia and stenosis of rectum without fistula is a billable ICD-10-CM diagnosis code (Q42.1).

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

  • CC as a secondary diagnosis (FY2027). Can raise the stay's MS-DRG severity tier.

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 Q42.1 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 1 Excludes1 note: K56 — Paralytic ileus and intestinal obstruction without hernia (via Q42.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 8 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 3 MS-DRGs: DRG 393 (MDC 06), DRG 394 (MDC 06), DRG 395 (MDC 06).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):MAL002 — Digestive congenital anomalies (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

Q42.0 — Congenital absence, atresia and stenosis of rectum with fistula, Q42.2 — Congenital absence, atresia and stenosis of anus with fistula, Q42.3 — Congenital absence, atresia and stenosis of anus without fistula, Q42.8 — Congenital absence, atresia and stenosis of other parts of large intestine, Q42.9 — Congenital absence, atresia and stenosis of large intestine, part unspecified, Q45.8 — Other specified congenital malformations of digestive system, Q45.9 — Congenital malformation of digestive system, unspecified

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Intestinal Obstruction/Perforation) for risk-adjusted payment.

K68.19 — Other retroperitoneal abscess, P77.1 — Stage 1 necrotizing enterocolitis in newborn, P77.2 — Stage 2 necrotizing enterocolitis in newborn, P77.3 — Stage 3 necrotizing enterocolitis in newborn, P77.9 — Necrotizing enterocolitis in newborn, unspecified, P78.0 — Perinatal intestinal perforation, Q40.0 — Congenital hypertrophic pyloric stenosis, Q41.0 — Congenital absence, atresia and stenosis of duodenum, Q41.1 — Congenital absence, atresia and stenosis of jejunum, Q41.2 — Congenital absence, atresia and stenosis of ileum, Q41.8 — Congenital absence, atresia and stenosis of other specified parts of small intestine, Q41.9 — Congenital absence, atresia and stenosis of small intestine, part unspecified, Q42.0 — Congenital absence, atresia and stenosis of rectum with fistula, Q42.2 — Congenital absence, atresia and stenosis of anus with fistula, Q42.3 — Congenital absence, atresia and stenosis of anus without fistula, Q42.8 — Congenital absence, atresia and stenosis of other parts of large intestine, Q42.9 — Congenital absence, atresia and stenosis of large intestine, part unspecified, Q43.1 — Hirschsprung's disease, Q43.2 — Other congenital functional disorders of colon, Q43.3 — Congenital malformations of intestinal fixation, +55 more

Related risk categories

These categories interact through CMS's HCC hierarchy — one can suppress the other's risk-adjustment weight when both are present on a claim.

Intestine Transplant Status/Complications

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Digestive congenital anomalies).

Q40.2 — Other specified congenital malformations of stomach, Q40.3 — Congenital malformation of stomach, unspecified, Q40.8 — Other specified congenital malformations of upper alimentary tract, Q40.9 — Congenital malformation of upper alimentary tract, unspecified, Q41.0 — Congenital absence, atresia and stenosis of duodenum, Q41.1 — Congenital absence, atresia and stenosis of jejunum, Q41.2 — Congenital absence, atresia and stenosis of ileum, Q41.8 — Congenital absence, atresia and stenosis of other specified parts of small intestine, Q41.9 — Congenital absence, atresia and stenosis of small intestine, part unspecified, Q42.0 — Congenital absence, atresia and stenosis of rectum with fistula, Q42.2 — Congenital absence, atresia and stenosis of anus with fistula, Q42.3 — Congenital absence, atresia and stenosis of anus without fistula, Q42.8 — Congenital absence, atresia and stenosis of other parts of large intestine, Q42.9 — Congenital absence, atresia and stenosis of large intestine, part unspecified, Q43.0 — Meckel's diverticulum (displaced) (hypertrophic), Q43.1 — Hirschsprung's disease, Q43.2 — Other congenital functional disorders of colon, Q43.3 — Congenital malformations of intestinal fixation, Q43.4 — Duplication of intestine, Q43.5 — Ectopic anus, +41 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Agenesis”, “Atresia, atretic”, “Impervious”, …; these codes share that main term but sit in a different category of the Tabular List.

Q39.3 — Congenital stenosis and stricture of esophagus (cardia, congenital), Q39.8 — Other congenital malformations of esophagus (esophagus), Q40.0 — Congenital hypertrophic pyloric stenosis (pylorus, congenital), Q40.2 — Other specified congenital malformations of stomach (stomach), Q40.8 — Other specified congenital malformations of upper alimentary tract (alimentary tract, upper), Q41.0 — Congenital absence, atresia and stenosis of duodenum (duodenum), Q41.1 — Congenital absence, atresia and stenosis of jejunum (jejunum), Q41.2 — Congenital absence, atresia and stenosis of ileum (ileum), Q41.8 — Congenital absence, atresia and stenosis of other specified parts of small intestine (intestine, congenital, specified NEC), Q41.9 — Congenital absence, atresia and stenosis of small intestine, part unspecified (intestine), Q44.0 — Agenesis, aplasia and hypoplasia of gallbladder (gallbladder), Q44.1 — Other congenital malformations of gallbladder (gallbladder), Q44.2 — Atresia of bile ducts (bile duct), Q44.3 — Congenital stenosis and stricture of bile ducts (bile duct, congenital), Q44.5 — Other congenital malformations of bile ducts (bile duct or passage), Q44.79 — Other congenital malformations of liver (liver), Q45.0 — Agenesis, aplasia and hypoplasia of pancreas (pancreas), Q45.8 — Other specified congenital malformations of digestive system (alimentary tract), Q50.01 — Congenital absence of ovary, unilateral (ovary, unilateral), Q50.02 — Congenital absence of ovary, bilateral (ovary, bilateral), +400 more

Contextual Map

Every relationship of Q42.1 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 Q42.1 with this related code in Claim Check

Hierarchy

Referenced by Excludes1 notes

Clinical classification (CCSR)

Risk adjustment (CMS-HCC)

  • HCC 78 — Intestinal Obstruction/Perforation [CMS-HCC]— CMS-HCC V28 · 2026

MS-DRG Grouper

MDC crossing

  • MDC 06 — Diseases and Disorders of the Digestive System[MDC crossing]: “Diseases and Disorders of the Digestive System — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 5,748 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Index entries

  • Absence (of) (organ or part) (complete or partial), rectum (congenital)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Agenesis, rectum[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Atresia, atretic, rectum[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Hypoplasia, hypoplastic, rectum[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Imperforate (congenital), rectum[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Impervious (congenital), rectum[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Stricture, rectum (sphincter), congenital[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027

Nearest codes

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

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.

Indexed Clinical Terms (7)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

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
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v44 Release, file and checksum · Publisher’s page
Risk adjustment Official source data
2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release 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. "Q42.1 — Congenital absence, atresia and stenosis of rectum without fistula." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/q42.1-congenital-absence-atresia-and-stenosis-of-rectum-without-fistula

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Congenital absence, atresia and stenosis of rectum without fistula

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to Q42.1 in its code family, with their registry titles.

View all codes in the Q42 family