2027 ICD-10-CM Diagnosis Code P56.0Hydrops fetalis due to isoimmunization

ICD-10-CM Codes›P00–P96›P50-P61›P56

ICD-10-CM P56.0
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

P56.0 is a billable ICD-10-CM diagnosis code for hydrops fetalis due to isoimmunization. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 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 25 closely related codes. Coders also document this condition as hydrops fetalis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Hemolytic jaundice and perinatal jaundice.

For Medicare Advantage risk adjustment, P56.0 maps to CMS-HCC Category 109 (Acquired Hemolytic, Aplastic, and Sideroblastic Anemias) under the V28 model, adding a risk factor of about 1.144 for a community, non-dual, aged beneficiary in payment year 2027.

Code Identity

ICD-10-CM Code
P56.0
Billable Status
Yes — Valid for Submission
Code Describes
Hydrops fetalis due to isoimmunization
Short Description
Hydrops fetalis due to isoimmunization
Same as the full description in the CMS dataset.
Parent Code
P56
Hydrops fetalis due to hemolytic disease

Code Classification

ChapterP00–P96Certain conditions originating in the perinatal period
SectionP50-P61Hemorrhagic and hematological disorders of newborn
CategoryP56Hydrops fetalis due to hemolytic disease
This CodeP56.0Hydrops fetalis due to isoimmunization

Medicare Risk Adjustment (HCC)Billing

P56.0 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.

CMS-HCC V28 Category (Payment Model)
HCC 109— Acquired Hemolytic, Aplastic, and Sideroblastic Anemias
Payment HCC · PY 2027 one of 37 ICD-10-CM codes in this category
Risk Adjustment Factor (RAF) Weight
+1.144
community, non-dual, aged · ranges 0.529–1.815 across segments
Hierarchy
Top of its hierarchy
HCC 109 is not superseded by any other condition category
Prior Model (CMS-HCC V24)
Not mapped under V24
this diagnosis newly risk-adjusts under the V28 model
Part D (RxHCC)
Not mapped
P56.0 does not risk-adjust in the RxHCC prescription drug model

Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Hydrops fetalis
  • Hydrops fetalis due to isoimmunization

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to P56.0: its own notes plus those printed at P56, block P50-P61, and Chapter 16. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From Chapter 16 (P00-P96) Certain conditions originating in the perinatal period applies to 463 codes
  • conditions that have their origin in the fetal or perinatal period (before birth through the first 28 days after birth) even if morbidity occurs later

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From P56 Hydrops fetalis due to hemolytic disease applies to 3 codes
  • hydrops fetalis NOS (P83.2)
From Block P50-P61 Hemorrhagic and hematological disorders of newborn applies to 67 codes
  • congenital stenosis and stricture of bile ducts (Q44.3)
  • Crigler-Najjar syndrome (E80.5)
  • Dubin-Johnson syndrome (E80.6)
  • Gilbert syndrome (E80.4)
  • hereditary hemolytic anemias (D55-D58)

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.

From Chapter 16 (P00-P96) Certain conditions originating in the perinatal period applies to 463 codes
  • congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • tetanus neonatorum (A33)

Notes

General instructions on how these codes are used.

From Chapter 16 (P00-P96) Certain conditions originating in the perinatal period applies to 463 codes
  • Codes from this chapter are for use on newborn records only, never on maternal records

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name P56.0, its category, or a range that includes it.

Excludes1 4

These codes carry an Excludes1 note naming P56.0: they are not reported together with it, unless the two conditions are unrelated.

  • D56.0 Alpha thalassemia
    hydrops fetalis due to isoimmunization (P56.0)
  • P83 Other conditions of integument specific to newborn
    hydrops fetalis due to hemolytic disease (P56.-) names P56.-, which includes this code
  • K72 Hepatic failure, not elsewhere classified
    icterus of newborn (P55-P59) names P55-P59, which includes this code
  • P58 Neonatal jaundice due to other excessive hemolysis
    jaundice due to isoimmunization (P55-P57) names P55-P57, which includes this code

Excludes2 1

These codes carry an Excludes2 note naming P56.0: its condition is not part of those codes, and both may be reported when the patient has both.

  • Block R70-R79 Abnormal findings on examination of blood, without diagnosis
    hemorrhagic and hematological disorders of newborn (P50-P61) names P50-P61, which includes this code

Code Also 1

These codes say P56.0 may also be needed to fully describe the condition. The note gives no sequencing direction.

  • K76.82 Hepatic encephalopathy
    icterus of newborn (P55-P59) names P55-P59, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR PNL007
Hemolytic jaundice and perinatal jaundice
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Edema

Edema means swelling caused by fluid in your body's tissues. It usually occurs in the feet, ankles and legs, but it can involve your entire body.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert P56.0 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
773.3 Hydrops fetalis:isoimm
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About P56.0Overview

What is the ICD-10 code for hydrops fetalis due to isoimmunization?

The ICD-10-CM code for hydrops fetalis due to isoimmunization is P56.0 (sometimes written as P560). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is P56.0 (Hydrops fetalis due to hemolytic disease) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report hydrops fetalis due to isoimmunization on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does P56.0 group to?

When hydrops fetalis due to isoimmunization is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, with relative weights from 4.1073 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.

Is P56.0 a CC or MCC?

CMS lists P56.0 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 25 closely related codes in its exclusion list.

Can P56.0 be reported with P83.2?

Not as a rule. The Excludes1 note at P56, which applies to P56.0, lists "hydrops fetalis NOS (P83.2)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).

What HCC is P56.0?

P56.0 (hydrops fetalis due to isoimmunization) maps to CMS-HCC Category 109 (Acquired Hemolytic, Aplastic, and Sideroblastic Anemias), commonly written as HCC 109, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It does not map to any RxHCC in the Part D prescription drug model.

Does P56.0 risk-adjust for Medicare Advantage payment?

Yes. When documented and reported on a Medicare Advantage encounter, P56.0 adds a risk adjustment factor of about 1.144 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.529 to 1.815 depending on the payment segment). HCC 109 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 109 category page.