ICD-10 K66.1
Billable / Specific MCCHemoperitoneum
About ICD-10-CM K66.1
ICD-10-CM code K66.1 represents Hemoperitoneum. This is a billable/specific code in the Digestive System chapter (block K66). The 2026 edition of ICD-10-CM K66.1 became effective on October 1, 2025.
Coding Tips for K66.1
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
K66.1 is designated MCC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-MCC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag MCC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Inclusion Terms / Approximate Synonyms
Clinical terms and conditions classified under K66.1. Per CMS ICD-10-CM Tabular 2026.
- Peritoneal hematoma
- Peritoneal hemorrhage
Type 1 Excludes
Pure excludes, these codes can never be coded together with K66.1. The conditions are mutually exclusive (e.g., congenital vs acquired forms).
- traumatic hemoperitoneum (S36.8-)
Type 2 Excludes
Not included here, the excluded code is not part of K66.1, but a patient may have both conditions at the same time. Both codes may be coded together when applicable.
- retroperitoneal hematoma (K68.3)
- retroperitoneal hemorrhage (K68.3)
Inpatient DRG Impact, MCC
code Hemoperitoneum. As a Major Complication/Comorbidity (MCC), this can shift the DRG assignment to a higher-weighted category, substantial reimbursement impact.
Medicare LCD Coverage for K66.1
Local Coverage Determinations (LCDs) from CMS MACs that list K66.1 as a covered diagnosis.
Showing top 9. Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing K66.1.
1 Medicare
CPT Codes Commonly Billed with K66.1
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
We don't have CPT pairings indexed for this specific code yet. Use the CPT search above to find common procedures, or check your payer's published medical policy for code-specific guidance.
Convert K66.1 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| K66.1 | 56881 | 00000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To K66.1
Other codes in section K65-K68 (Diseases of peritoneum and retroperitoneum).
ICD-10 K66.1, Billing FAQ
Is ICD-10 code K66.1 billable? +
Yes, K66.1 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
What other names or terms map to K66.1? +
ICD-10 K66.1 includes: Peritoneal hematoma; Peritoneal hemorrhage.
What codes are Type 1 Excludes for K66.1? +
Type 1 Excludes (never code together with K66.1): traumatic hemoperitoneum (S36.8-)
What codes are Type 2 Excludes for K66.1? +
Type 2 Excludes (may be coded together when both conditions exist): retroperitoneal hematoma (K68.3); retroperitoneal hemorrhage (K68.3)
Is K66.1 a CC or MCC for inpatient DRG? +
Yes, this code is designated as MCC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What ICD-9 codes does K66.1 map to? +
Per CMS GEMs, K66.1 maps to ICD-9 codes: 56881. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
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