S31.001A Unspecified open wound of lower back and pelvis with penetration into retroperitoneum, initial encounter

ICD-10-CM Diagnosis Code S31.001A Reference

ICD-10-CM code S31.001A identifies an unspecified open wound of the lower back and pelvis with penetration into the retroperitoneum during an initial encounter. This terminology is active for the 2026 version and is classified under the semantic type of injury or poisoning. The code appears in CMS MS-DRG definitions manuals. 1 2 3

Plain-language overview

Code S31.001A represents an injury diagnosis for an initial encounter involving an unspecified open wound to the lower back and pelvis that penetrates into the retroperitoneum. 1

What this code represents

The official terminology record assigns the semantic type of Injury or Poisoning to S31.001A, establishing the clinical nature of this specific diagnosis code. 1

The parent concept for S31.001A is S31.001, which is the unspecified open wound of lower back and pelvis with penetration into retroperitoneum without specifying the encounter. 1

Coding details

The terminology record for S31.001A lists S31.001S as another concept under the same parent code, but the excerpt does not define the specific meaning of the seventh character. 4

The S31.001A terminology record is active for the 2026 ICD-10-CM version and possesses narrower concepts within the official terminology hierarchy, according to the source excerpt. 1

Documentation considerations

The official preferred name for S31.001A specifies an unspecified open wound of the lower back and pelvis with penetration into the retroperitoneum during an initial encounter. 1

Coverage and utilization context

The S31.001A diagnosis code is listed in the CMS MS-DRG version 36.0 and version 42.0 definitions manuals alongside related open wound diagnoses of the lower back and pelvis. 2 3

What the sources add

The terminology authority defines S31.001A as an active injury concept, while the CMS manuals list this exact code alongside related open wound diagnoses of the abdomen and pelvis. 1 2 3

Comparing the CMS manuals, S31.001A appears in both version 36.0 and version 42.0 definitions, showing its presence across two separate manual editions. 2 3

Sources

1. ICD-10-CM S31.001A terminology record — National Cancer Institute Enterprise Vocabulary Services; accessed 2026-07-27.
2. ICD-10-CM/PCS MS-DRG v36.0 Definitions Manual — cms.gov; accessed 2026-07-27.
3. ICD-10-CM/PCS MS-DRG v42.0 Definitions Manual — cms.gov; accessed 2026-07-27.
4. EVS Explore — evsexplore.semantics.cancer.gov; accessed 2026-07-27.
5. EVS Explore — evsexplore.semantics.cancer.gov; accessed 2026-07-27.