P56.0 Hydrops fetalis due to isoimmunization

The ICD-10-CM code for Hydrops fetalis due to isoimmunization is P56.0 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

16: Certain conditions originating in the perinatal period (P00-P96)

Section

P50-P61: Hemorrhagic and hematological disorders of newborn (P50-P61)

Category P56

5 codes (3 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to P56.0:

• Dropsy, dropsical › newborn due to isoimmunization
• Hydrops › newborn (idiopathic) › due to › Rh incompatibility
• Hydrops › newborn (idiopathic) › due to › isoimmunization (ABO) (Rh)
• Hydrops › fetalis › due to › Rh incompatibility
• Hydrops › fetalis › due to › isoimmunization (ABO) (Rh)
• Hydrops › fetalis › due to › ABO isoimmunization
• Isoimmunization NEC › newborn › with › hydrops fetalis
• Hydrops › newborn (idiopathic) › due to › ABO isoimmunization

U.S. Hospital Utilization

P56.0 appeared in too few sampled U.S. inpatient stays in 2023 to report a national estimate (AHRQ suppresses counts of 10 or fewer) — a rare inpatient diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

Use of Z05 codes (newborn suspected condition ruled out)

1) Use of Z05 codes Assign a code from category Z05, Observation and evaluation of newborn for suspected diseases and conditions ruled out, to identify those instances when a healthy newborn is evaluated for a suspected condition/disease that is determined after study not to be present. Do not use a code from category Z05 when the patient is documented to have signs or symptoms of a suspected problem; in such cases code the sign or symptom.

Z05 on other than the birth record

2) Z05 on other than the birth record A code from category Z05 may also be assigned as a principal or first- listed code for readmissions or encounters when the code from category Z38 code no longer applies. Codes from category Z05 are for use only for healthy newborns and infants for which no condition after study is found to be present.

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)