Is ICD-10-CM code S91 billable?

No, S91 (Open wound of ankle, foot and toes) is a non-billable ICD-10-CM code. It must be coded to a more specific subcategory before it can be used for reimbursement.

What chapter does ICD-10-CM code S91 belong to?

S91 belongs to Chapter 19 of the ICD-10-CM tabular list: S00–T88 (Injury, Poisoning and Certain Other Consequences of External Causes).

S91Not billable, use a more specific code below

Open wound of ankle, foot and toes

In Injuries to the ankle and foot (S90-S99), chapter 19: Injury, Poisoning and Certain Other Consequences of External Causes

360 billable codes under S91: none are a CC or MCC; none map to an HCC.

Instructional notes

Excludes1: not coded here, use a different code

open fracture of ankle, foot and toes (S92.-with 7th character B)
traumatic amputation of ankle and foot (S98.-)

Code also: add a code for this too, order depends on the encounter

any associated wound infection

Also applies, from Injuries to the ankle and foot (S90-S99)

These notes sit on S90-S99 and apply to every code under it, including S91.

Excludes2: not included here, code separately if applicable

burns and corrosions (T20-T32)
fracture of ankle and malleolus (S82.-)
frostbite (T33-T34)
insect bite or sting, venomous (T63.4)

Official coding guidelines

From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.

Covers 7th character use and coding of injuries, fractures, burns, drug and toxic effects, abuse and neglect, and complications of care (S00-T88).

Application of 7th Characters in Chapter 19 (page 77)
Coding of Injuries (page 78)
Coding of Traumatic Fractures (page 79)
Coding of Burns and Corrosions (page 80)
Adverse Effects, Poisoning, Underdosing and Toxic Effects (page 82)
Adult and child abuse, neglect and other maltreatment (page 85)
Complications of care (page 85)

Read Section I.C.19 (page 77)

Codes under S91

S91 can't be used on a claim. Pick a billable code below; grey headings group them.

S91 MS-DRGs

As the principal diagnosis, the billable codes under S91 group to these 9 MS-DRGs (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.

DRG 604 Trauma to the Skin, Subcutaneous Tissue and Breast with MCC (200 of 360 codes)
DRG 605 Trauma to the Skin, Subcutaneous Tissue and Breast without MCC (200 of 360 codes)
DRG 949 Aftercare with CC/MCC (120 of 360 codes)
DRG 950 Aftercare without CC/MCC (120 of 360 codes)
DRG 963 Other Multiple Significant Trauma with MCC (120 of 360 codes)
DRG 964 Other Multiple Significant Trauma with CC (120 of 360 codes)
DRG 965 Other Multiple Significant Trauma without CC/MCC (120 of 360 codes)
DRG 913 Traumatic Injury with MCC (40 of 360 codes)
DRG 914 Traumatic Injury without MCC (40 of 360 codes)

Other codes that refer to S91

Notes on these codes point to S91.

S71 Excludes2: open wound of ankle, foot and toes (S91.-)
S81 Excludes2: open wound of ankle and foot (S91.-)
S94 Code Also: any associated open wound (S91.-)
S95 Code Also: any associated open wound (S91.-)
S96 Code Also: any associated open wound (S91.-)

About the condition

Plain-language background from MedlinePlus (National Library of Medicine), not coding guidance.

Ankle Injuries and Disorders

Your ankle bone and the ends of your two lower leg bones make up the ankle joint. Your ligaments, which connect bones to one another, stabilize and support it. Your muscles and tendons move it.

Foot Injuries and Disorders

Each of your feet has 26 bones, 33 joints, and more than 100 tendons, muscles, and ligaments. No wonder a lot of things can go wrong. Here are a few common problems:

Code history

Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.