S56.021ALaceration of flexor muscle, fascia and tendon of right thumb at forearm level, initial encounter

S56.021A is the ICD-10-CM diagnosis code for laceration of flexor muscle, fascia and tendon of right thumb at forearm level, initial encounter. It belongs to category S56 (injury of muscle, fascia and tendon at forearm level), block S50-S59 (injuries to the elbow and forearm) and chapter 19 (injury, poisoning and certain other consequences of external causes). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

The 7th character "A" means initial encounter: use it while the patient is receiving active treatment for the condition.

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 564 (Other Musculoskeletal System and Connective Tissue Diagnoses with MCC, relative weight 1.4908), DRG 565 (Other Musculoskeletal System and Connective Tissue Diagnoses with CC, relative weight 0.9783), DRG 566 (Other Musculoskeletal System and Connective Tissue Diagnoses without CC/MCC, relative weight 0.7378), DRG 963 (Other Multiple Significant Trauma with MCC, relative weight 2.6363), DRG 964 (Other Multiple Significant Trauma with CC, relative weight 1.4972) and DRG 965 (Other Multiple Significant Trauma without CC/MCC, relative weight 1.0059), in MDC 08 (Diseases and Disorders of the Musculoskeletal System and Connective Tissue) and MDC 24 (Multiple Significant Trauma), 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 has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 881.20 (open wound of forearm, with tendon involvement).