Wiktionary
thoracostomy
n. Incision into the chest wall, with maintenance of the opening for drainage.
Wikipedia
Thoracostomy
A thoracostomy is a small incision of the chest wall, with maintenance of the opening for drainage. It is most commonly used for the treatment of a pneumothorax. This is performed by surgeons (or emergency medicine physicians), usually via needle thoracostomy or with a thoracostomy tube (chest tube).
A thoracostomy is commonly confused with thoracotomy, which is a larger incision commonly used to gain access to organs within the chest.