ICD-10-PCS is vastly different from the ICD-9-CM procedure codes inpatient coders currently use.
You probably know that meaning of a body part value in the Medical and Surgical section always depends on the body system value. The body part value K in Lower Arteries represents the right femoral artery. In the Upper Bones body system, K represents the right ulna.
One of the purposes of the switch to ICD-10-PCS is increase specificity, so the following guideline should come as no surprise:
The procedure codes in the general anatomical regions body systems should only be used when the procedure is performed on an anatomical region rather than a specific body part (e.g., root operations Control and Detachment, Drainage of a body cavity) or on the rare occasion when no information is available to support assignment of a code to a specific body part.
Example: Control of postoperative hemorrhage is coded to the root operation Control found in the general anatomical regions body systems.
The ICD-10-PCS guidelines also instruct coders to query a physician if the documentation is insufficient.