2027 ICD-10-CM Diagnosis Code P55.0Rh isoimmunization of newborn
P55.0 is a billable ICD-10-CM diagnosis code for rh isoimmunization of newborn. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 794. Coders also document this condition as hemolytic disease of fetus OR newborn due to RhD isoimmunization. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Hemolytic jaundice and perinatal jaundice.
For Medicare Advantage risk adjustment, P55.0 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
Code Classification
Medicare Risk Adjustment (HCC)Billing
P55.0 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.
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.
- Hemolytic disease of fetus OR newborn due to RhD isoimmunization
- Rhesus isoimmunization due to anti-c
- Rhesus isoimmunization due to anti-Cw
- Rhesus isoimmunization due to anti-D
- Rhesus isoimmunization due to anti-E
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to P55.0: its own notes plus those printed at 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.
- 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.
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 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 P55.0, its category, or a range that includes it.
Excludes1 6
These codes carry an Excludes1 note naming P55.0: they are not reported together with it, unless the two conditions are unrelated.
- D58 Other hereditary hemolytic anemiashemolytic anemia of the newborn (P55.-) names P55.-, which includes this code
- R17 Unspecified jaundiceneonatal jaundice (P55, P57-P59) names P55, which includes this code
- R71 Abnormality of red blood cellsnewborn anemia due to isoimmunization (P55.-) names P55.-, which includes this code
- R76.0 Raised antibody titerisoimmunization affecting newborn (P55.-) names P55.-, which includes this code
- K72 Hepatic failure, not elsewhere classified
- P58 Neonatal jaundice due to other excessive hemolysis
Excludes2 2
These codes carry an Excludes2 note naming P55.0: its condition is not part of those codes, and both may be reported when the patient has both.
- D59.1 Other autoimmune hemolytic anemiashemolytic disease of newborn (P55.-) names P55.-, which includes this code
- Block R70-R79 Abnormal findings on examination of blood, without diagnosis
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Antibodies, maternal (blood group) See: Isoimmunization, affecting management of pregnancy;
Disease, diseased See Also: Syndrome;
Icterus See Also: Jaundice;
gravis, newborn P55.0
Isoimmunization NEC See Also: Incompatibility;
Rhesus (Rh) factor P55.0
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Erythroblastosis, Fetal
a condition characterized by the abnormal presence of erythroblasts in the circulation of the fetus or newborns. it is a disorder due to blood group incompatibility, such as the maternal alloimmunization by fetal antigen rh factors leading to hemolysis of erythrocytes, hemolytic anemia (anemia, hemolytic), general edema (hydrops fetalis), and severe jaundice in newborn.
Patient EducationClinical
Rh Incompatibility
There are four major blood types: A, B, O, and AB. The types are based on substances found on your blood cells. Your blood type also has a positive or negative sign. This is called Rh factor, which is a protein. If your blood cells have this protein, you are Rh-positive. If you don't, you are Rh-negative.
The full article covers:
- What is the Rh factor?
- What is Rh incompatibility?
- How is Rh incompatibility diagnosed?
- How is Rh incompatibility treated?
- Can Rh incompatibility be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert P55.0 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About P55.0Overview
What is the ICD-10 code for rh isoimmunization of newborn?
The ICD-10-CM code for rh isoimmunization of newborn is P55.0 (sometimes written as P550). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is P55.0 (Hemolytic disease of newborn) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report rh isoimmunization of newborn on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does P55.0 group to?
When rh isoimmunization of newborn is the principal diagnosis on an inpatient stay, it groups to MS-DRG 794 (neonate with Other Significant Problems), which carries a relative weight of 1.4934. Higher weights mean higher Medicare reimbursement.
Can P55.0 be reported with Q44.3?
Not as a rule. The Excludes1 note at block P50-P61, which applies to P55.0, lists "congenital stenosis and stricture of bile ducts (Q44.3)". 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 is the ICD-9 equivalent of P55.0?
Under the General Equivalence Mappings, rh isoimmunization of newborn converts to ICD-9-CM 773.0 (NB hemolyt dis:rh isoimm). The mapping is a direct match.
What HCC is P55.0?
P55.0 (rh isoimmunization of newborn) 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 P55.0 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, P55.0 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.
