Final answer:
The correct code to report this condition is S61.032A - puncture wound without foreign body of left thumb without damage to the nail, initial encounter.
Step-by-step explanation:
The correct code to report this condition is 1) S61.032A Puncture wound without foreign body of left thumb without damage to the nail, initial encounter. This code accurately describes the injury Paul sustained while building a swing set in his backyard. It specifies that there was a puncture wound on the left thumb, without any damage to the nail, and it was his initial encounter with the healthcare provider for treatment.