Question

A young woman develops left sided pneumothorax following blunt injury to the chest. The most appropriate site to insert a chest tube would be

• A. 2nd intercostal space in mid clavicular line
• B. 2nd intercostal space in anterior axillary line
• C. 5th intercostal space in anterior axillary line
• D. 5th intercostal space in posterior axillary line

Hint:

Think about the "triangle of safety" used for tube thoracostomy.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question describes a young woman with blunt chest trauma who develops a left-sided pneumothorax, and asks for the correct anatomical landmark to place a chest tube (tube thoracostomy).

Step 2: Key Concept or Approach:
Chest tube insertion for pneumothorax or haemothorax is always done through the "triangle of safety" — a region bordered by the lateral edge of pectoralis major anteriorly, the lateral edge of latissimus dorsi posteriorly, and a horizontal line at the level of the nipple, roughly the 5th intercostal space, with its apex below the axilla. Entering here keeps the tube above the diaphragm and away from the heart, great vessels, and the internal mammary artery, while staying clear of major muscle and neurovascular structures.

Step 3: Working Through the Options:
The 2nd intercostal space in the mid-clavicular line is the site used for emergency needle decompression of a tension pneumothorax, not for a formal chest tube — a needle here buys time, but a tube placed at this level sits close to major vessels near the sternum and heals poorly. The 2nd intercostal space in the anterior axillary line is not a recognised chest tube landmark either; it is too high, again near the axillary vessels and outside the safe triangle. The 5th intercostal space in the anterior axillary line falls squarely within the triangle of safety, over relatively thin muscle, above the diaphragm and lateral to the heart — this is the correct and standard site. The 5th intercostal space in the posterior axillary line is too far back: a patient lying supine cannot comfortably rest on a tube placed there, it is prone to kinking or being compressed under the patient's own weight, and this approach risks injury to the long thoracic nerve running along the chest wall.

Step 4: Conclusion:
The correct answer is the 5th intercostal space in the anterior axillary line.