The inclusion criteria were as below:
  1. Research type: Randomized controlled trials (RCTs), controlled clinical trial, prospective/retrospective cohort study or studies that have at least two arms of comparison;
  2. An object of study: Patients must have been <=18 years of age, who diagnosed with CPAM while asymptomatic;
  3. Intervening measure: Patients received surgical treatment for CPAM in different operation timing;
  4. Outcome indicator: The study included at least one of the following information was reported: complications, length of hospital stay, pleural drainage/chest tube duration, ventilation outcomes, mortality;
  5. Written in English only;