triangle of safety for thoracentesis

These studies support the British Thoracic Society (BTS) recommendation to perform thoracentesis—if possible—in the triangle of safety. This triangle is bordered anteriorly by the lateral edge of the pectoralis major, laterally by the lateral edge of the latissimus dorsi, superiorly by the base of the axilla, and inferiorly by the line of the fifth intercostal space. The other landmarks provided are all locations where thoracentesis can be performed, however, are not as ideal (choices B, C, and D are incorrect).

Magnified CT image demonstrating tortuous course of the intercostal artery within the posterior costal space.