How would you approach a stable 3 cm iatrogenic pneumothorax in an asymptomatic patient?

I think it is quite reasonable to continue to monitor in this situation. I probably would take comorbidities and reliability into consideration to decide if this is someone I would admit to the hospital VS follow up as outpatient.

Most iatrogenic pneumothorax after bronchoscopy resolve without intervention. If asymptomatic and without radiographic evidence of developing tension physiology close monitoring while on 100% O2 is appropriate without intervention unless the patient becomes symptomatic or develops signs of tension physiology on subsequent imaging. At that point, intervention with placement of a small bore chest tube or needle aspiration would be appropriate.