2027 ICD-10-CM Diagnosis Code P78.1Other neonatal peritonitis

ICD-10-CM Codes›P00–P96›P76-P78›P78

ICD-10-CM P78.1
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

P78.1 is a billable ICD-10-CM diagnosis code for other neonatal peritonitis. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 794. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Neonatal digestive and feeding disorders.

Code Identity

ICD-10-CM Code
P78.1
Billable Status
Yes — Valid for Submission
Code Describes
Other neonatal peritonitis
Short Description
Other neonatal peritonitis
Same as the full description in the CMS dataset.
Parent Code
P78
Other perinatal digestive system disorders

Code Classification

ChapterP00–P96Certain conditions originating in the perinatal period
SectionP76-P78Digestive system disorders of newborn
CategoryP78Other perinatal digestive system disorders
This CodeP78.1Other neonatal peritonitis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute infectious peritonitis
  • Acute localized peritonitis caused by infection
  • Aseptic peritonitis
  • Bacterial peritonitis
  • Fat necrosis of peritoneum
  • Fibrinous peritonitis
  • Infectious peritonitis
  • Mesenteric fat necrosis
  • Mesenteric peritonitis with mesenteric fat necrosis
  • Neonatal peritonitis
  • Peritonitis
  • Pneumococcal peritonitis
  • Primary peritonitis
  • Serositis

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to P78.1: its own notes plus those printed at P78 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

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.

  • Neonatal peritonitis NOS

Excludes1

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

From P78 Other perinatal digestive system disorders applies to 10 codes

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 P78.1, its category, or a range that includes it.

Excludes1 1

These codes carry an Excludes1 note naming P78.1: they are not reported together with it, unless the two conditions are unrelated.

  • K65 Peritonitis
    neonatal peritonitis (P78.0-P78.1) names P78.0-P78.1, 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 PNL012
Neonatal digestive and feeding disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Peritoneal Disorders

Your peritoneum is the tissue that lines your abdominal wall and covers most of the organs in your abdomen. A liquid, peritoneal fluid, lubricates the surface of this tissue.

Read the full article at MedlinePlus

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

Convert P78.1 to ICD-9-CMHistory

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

ICD-9-CM
777.8 Perinat GI sys dis NEC
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 P78.1Overview

What is the ICD-10 code for other neonatal peritonitis?

The ICD-10-CM code for other neonatal peritonitis is P78.1 (sometimes written as P781). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is P78.1 (Other perinatal digestive system disorders) a billable code?

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

What MS-DRG does P78.1 group to?

When other neonatal peritonitis 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.

What is the ICD-9 equivalent of P78.1?

Under the General Equivalence Mappings, other neonatal peritonitis converts to ICD-9-CM 777.8 (perinat GI sys dis NEC). The mapping is approximate, so confirm the match fits the documentation.