2027 ICD-10-CM Diagnosis Code Q89.4Conjoined twins
ICD-10-CM Codes›Q00-Q99›Q80-Q89›Q89
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- POA Exempt
- Chronic Condition
Q89.4 is a billable ICD-10-CM diagnosis code for conjoined twins. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 393 through 395, 791, 793. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 3 closely related codes. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified congenital anomalies.
Code Identity
Code Classification
Present on Admission (POA)Billing
Q89.4 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Other congenital malformations (Q80-Q89).
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Anadidymus
- Anakatadidymus
- Asymmetrical conjoined twins
- Cephalothoracopagus
- Conjoined twins
- Cranial duplication
- Craniopagus
- Craniopagus frontalis
- Craniopagus occipitalis
- Craniopagus parasiticus
- Craniopagus parietalis
- Deradelphus
- Desmiognathus
- Dicephalic parapagus
- Dicephalus dipus dibrachius
- Dicephalus dipus tetrabrachius
- Dicephalus dipus tribrachius
- Dicephalus tripus tribrachius
- Dipygus
- Dithoracic parapagus
- Epignathus
- Fetal conjoined twins
- Fetal epignathus
- Fetal epignathus with conjoined twins
- Fetal neoplasm
- Fetus in fetu
- Gastrothoracopagus
- Gastrothoracopagus dipygus
- Heterodymus
- Ischiomelus
- Ischiopagus
- Janiceps
- Katadidymus
- Monocephalus
- Omphalopagus
- Opodidymus
- Parapagus
- Parasitic twin of asymmetrical conjoined twins
- Polysomia
- Pygodidymus
- Pygopagus
- Rachipagus
- Sternopagus
- Symmetrical conjoined twins
- Syncephalus
- Thoracodelphus
- Thoracomelus
- Thoracoomphalopagus
- Thoracopagus
- Thoracopagus epigastricus
- Thoracopagus parasiticus
- Thoracopagus with conjoined atria
- Thoracopagus with conjoined atria and ventricles
- Thoracopagus with separate hearts and common pericardial sac
- Thoracopagus with separate hearts and pericardial sacs
- Xiphopagus
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to Q89.4: its own notes plus those printed at Chapter 17. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Craniopagus
- Dicephaly
- Pygopagus
- Thoracopagus
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
Notes
General instructions on how these codes are used.
- Codes from this chapter are not for use on maternal records
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Conjoined twins Q89.4
Craniopagus Q89.4
Dicephalus, dicephaly Q89.4
Epignathus Q89.4
Ischiopagus Q89.4
Janiceps Q89.4
Pygopagus Q89.4
Rudimentary (congenital) See Also: Agenesis;
Siamese twin Q89.4
Sternopagus Q89.4
Syncephalus Q89.4
Thoracopagus Q89.4
Twin (newborn) See Also: Newborn, twin;
conjoined Q89.4
Xiphopagus Q89.4
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Twins, Conjoined
monozygotic twins who are joined in utero. they may be well developed and share only a superficial connection, often in the frontal, transverse or sagittal body plane, or they may share a partial duplication of a body structure. alternatively, there may be a small and incompletely developed twin conjoined to a larger, more fully developed twin.
Patient EducationClinical
Birth Defects
A birth defect is a problem that happens while a baby is developing in the mother's body. Most birth defects happen during the first 3 months of pregnancy. One out of every 33 babies in the United States is born with a birth defect.
The full article covers:
- What are birth defects?
- What causes birth defects?
- Who is at risk of having a baby with birth defects?
- How are birth defects diagnosed?
- What are the treatments for birth defects?
- Can birth defects be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert Q89.4 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About Q89.4Overview
What is the ICD-10 code for conjoined twins?
The ICD-10-CM code for conjoined twins is Q89.4 (sometimes written as Q894). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is Q89.4 (Other congenital malformations, not elsewhere classified) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report conjoined twins on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does Q89.4 group to?
When conjoined twins is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 394, 395, 393, with relative weights from 0.6379 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.
Is Q89.4 a CC or MCC?
CMS lists Q89.4 as an MCC (major complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 3 closely related codes in its exclusion list.
Is Q89.4 exempt from POA reporting?
Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for conjoined twins on inpatient claims. The code appears in the Other congenital malformations (Q80-Q89) range of the CMS exempt list.
