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ICD-10-CM 2027 diagnosis code

K60.421Rectal fistula, complex, initial

✓ Billable / specific

K60.421 is a valid, billable ICD-10-CM code for rectal fistula, complex, initial. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Code last changed in FY2025 (effective October 1, 2024). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About K60.421

K60.421 is the ICD-10-CM diagnosis code for rectal fistula, complex, initial. It belongs to category K60 (fissure and fistula of anal and rectal regions), block K55-K64 (other diseases of intestines) and chapter 11 (diseases of the digestive system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within K60.42 (rectal fistula, complex), K60.421 is specifically for rectal fistula, complex, initial. Related codes cover persistent (K60.422), recurrent (K60.423) and unspecified (K60.429).

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 393 (Other Digestive System Diagnoses with MCC, relative weight 1.5881), DRG 394 (Other Digestive System Diagnoses with CC, relative weight 0.9228) and DRG 395 (Other Digestive System Diagnoses without CC/MCC, relative weight 0.6382), in MDC 06 (Diseases and Disorders of the Digestive System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It was added in FY2025, effective October 1, 2024.

Coding notes

Applicable toConditions and synonyms classified to this code
  • Rectal fistula, complex, new

Notes that apply from higher levels

Instructions written at a parent level also apply to K60.421.

› From K60.42 Rectal fistula, complex
Code also
  • , if applicable:
  • perianal abscess (K61.0)
  • rectovaginal fistula (N82.3)
  • stenosis of anus and rectum (K62.4)
› From K60.4 Rectal fistula
Excludes1
  • congenital fistula (Q43.6)
  • rectovaginal fistula (N82.3)
  • vesicorectal fistual (N32.1)
Code first
  • , if applicable:
  • Crohn's disease (K50.-)
  • ulcerative colitis (K51.-)
› From K60 Fissure and fistula of anal and rectal regions
Excludes2
  • abscess or cellulitis of anal and rectal regions (K61.-)
  • anal sphincter tear (healed) (nontraumatic) (old) (K62.81)

Broader instructions also apply from Chapter 11: Diseases of the digestive system.

Alphabetic index entries

2 entries

Terms in the official ICD-10-CM index that lead to K60.421.

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2025 (effective 10/1/2024): Added
  • No changes since FY2025.

Common questions about K60.421

Is K60.421 billable?

Yes. K60.421 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can K60.421 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict K60.421 as a principal diagnosis.

Is K60.421 a CC or MCC?

No. K60.421 is neither a CC nor an MCC under MS-DRG v44.0.

What DRG does K60.421 group to?

K60.421 is used in the MS-DRG v44.0 logic for MS-DRG 393 (Other Digestive System Diagnoses with MCC), MS-DRG 394 (Other Digestive System Diagnoses with CC) and MS-DRG 395 (Other Digestive System Diagnoses without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.