2027 ICD-10-CM Diagnosis Code S31.636APuncture wound of abdominal wall without foreign body, right flank with penetration into peritoneal cavity, initial encounter

ICD-10-CM Codes›S00–T88›S30-S39›S31

ICD-10-CM S31.636A
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

S31.636A is a billable ICD-10-CM diagnosis code for puncture wound of abdominal wall without foreign body, right flank with penetration into peritoneal cavity, initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 393 through 395, 963 through 965. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 160 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Open wounds of trunk, initial encounter.

Code Identity

ICD-10-CM Code
S31.636A
Billable Status
Yes — Valid for Submission
Code Describes
Puncture wound of abdominal wall without foreign body, right flank with penetration into peritoneal cavity, initial encounter
Short Description
Pnctr of abd wall w/o fb, r flank with penet perit cav, init
Parent Code
S31.636
Puncture wound of abdominal wall without foreign body, right flank with penetration into peritoneal cavity

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionS30-S39Injuries to the abdomen, lower back, lumbar spine, pelvis and external genitals
CategoryS31Open wound of abdomen, lower back, pelvis and external genitals
This CodeS31.636APuncture wound of abdominal wall without foreign body, right flank with penetration into peritoneal cavity, initial encounter

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Open wound of abdomen, lower back, pelvis and external genitals (S31). Use the following options for the applicable episode of care:

  • A - initial encounter
  • D - subsequent encounter
  • S - sequela

Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027, published by CMS and the National Center for Health Statistics.

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to S31.636A: its own notes plus those printed at S31, block S30-S39, and Chapter 19. 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 Block S30-S39 Injuries to the abdomen, lower back, lumbar spine, pelvis and external genitals applies to 2,679 codes
  • injuries to the abdominal wall
  • injuries to the anus
  • injuries to the buttock
  • injuries to the external genitalia
  • injuries to the flank
  • injuries to the groin

Excludes1

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

From S31 Open wound of abdomen, lower back, pelvis and external genitals applies to 558 codes
  • traumatic amputation of part of abdomen, lower back and pelvis (S38.2-, S38.3)

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 S31 Open wound of abdomen, lower back, pelvis and external genitals applies to 558 codes
From Block S30-S39 Injuries to the abdomen, lower back, lumbar spine, pelvis and external genitals applies to 2,679 codes
  • burns and corrosions (T20-T32)
  • effects of foreign body in anus and rectum (T18.5)
  • effects of foreign body in genitourinary tract (T19.-)
  • effects of foreign body in stomach, small intestine and colon (T18.2-T18.4)
  • frostbite (T33-T34)
  • insect bite or sting, venomous (T63.4)
From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • code to identify any retained foreign body, if applicable (Z18.-)

Code Also

A second code may be needed to fully describe the condition; the note gives no sequencing direction.

From S31 Open wound of abdomen, lower back, pelvis and external genitals applies to 558 codes

Notes

General instructions on how these codes are used.

From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
  • The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.

7th Character

Every code in the category takes a 7th character from the listed values, with the placeholder X filling any empty positions before it.

From S31 Open wound of abdomen, lower back, pelvis and external genitals applies to 558 codes
  • The appropriate 7th character is to be added to each code from category S31
Values for category S31 Encounter: Initial, Subsequent, Sequela
  • Ainitial encounter this code
  • Dsubsequent encounter
  • Ssequela

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name S31.636A, its category, or a range that includes it.

Excludes2 1

These codes carry an Excludes2 note naming S31.636A: its condition is not part of those codes, and both may be reported when the patient has both.

  • S31.1 Open wound of abdominal wall without penetration into peritoneal cavity
    open wound of abdominal wall with penetration into peritoneal cavity (S31.6-) names S31.6-, which includes this code

Use Additional Code 1

These codes say to use an additional code from the note, and S31.636A is one of the codes named.

  • S38.1 Crushing injury of abdomen, lower back, and pelvis
    open wound of abdominal wall (S31.-) names S31.-, which includes this code

Code Also 6

These codes say S31.636A may also be needed to fully describe the condition. The note gives no sequencing direction.

  • S33.1 Subluxation and dislocation of lumbar vertebra
    open wound of abdomen, lower back and pelvis (S31) names S31, which includes this code
  • S34 Injury of lumbar and sacral spinal cord and nerves at abdomen, lower back and pelvis level
    open wound of abdomen, lower back and pelvis (S31.-) names S31.-, which includes this code
  • S35 Injury of blood vessels at abdomen, lower back and pelvis level
    any associated open wound (S31.-) names S31.-, which includes this code
  • S36 Injury of intra-abdominal organs
    any associated open wound (S31.-) names S31.-, which includes this code
  • S37 Injury of urinary and pelvic organs
    any associated open wound (S31.-) names S31.-, which includes this code
  • S39 Other and unspecified injuries of abdomen, lower back, pelvis and external genitals
    any associated open wound (S31.-) names S31.-, which includes this code

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR INJ013
Open wounds of trunk, initial encounter
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Wounds and Injuries

An injury is damage to your body. It is a general term that refers to harm caused by accidents, falls, hits, weapons, and more. In the U.S., millions of people injure themselves every year. These injuries range from minor to life-threatening.

Read the full article at MedlinePlus

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

Code History & ChangesHistory

Replacement S31.636A replaces the following previously assigned code(s):

  • S31.639A - Pnctr w/o fb of abd wall, unsp q w penet perit cav, init
FY 2026AddedAdded to the ICD-10-CM code setEffective October 1, 2025.
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About S31.636AOverview

Is S31.636A a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report puncture wound of abdominal wall without foreign body, right flank with penetration into peritoneal cavity, initial encounter on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What does the 7th character A in S31.636A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for puncture wound of abdominal wall without foreign body, right flank with penetration into peritoneal cavity, such as an emergency visit or first evaluation.

What MS-DRG does S31.636A group to?

When puncture wound of abdominal wall without foreign body, right flank with penetration into peritoneal cavity, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 394, 964, 965, 395, 393, 963, with relative weights from 0.6379 to 2.6361 depending on complications. Higher weights mean higher Medicare reimbursement.

Is S31.636A a CC or MCC?

CMS lists S31.636A as an MCC (major complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 160 closely related codes in its exclusion list.

Can S31.636A be reported with a code from S38.2?

Not as a rule. The Excludes1 note at S31, which applies to S31.636A, lists "traumatic amputation of part of abdomen, lower back and pelvis (S38.2-, S38.3)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).