A patient with a large spontaneous pneumothorax (>2 cm rim on CXR, symptomatic) is referred for needle aspiration versus chest drain. The BTS guidelines recommend image-guided pleural access for drainage. Under ultrasound guidance for pleural interventions, the 'safe triangle' for chest drain insertion is defined by:

• A The midclavicular line in the 2nd intercostal space
• B Anterior border of latissimus dorsi, lateral border of pectoralis major, and the horizontal line at the level of the nipple (5th rib), in the mid-axillary line — avoiding the neurovascular bundle at the inferior rib margin ✓
• C The posterior axillary line at the 9th intercostal space
• D The midaxillary line at the 3rd intercostal space

Explanation

The 'safe triangle' for chest drain insertion (BTS guidelines) is bounded by: the anterior border of the latissimus dorsi (posterior), the lateral border of pectoralis major (anterior), a line at the level of the nipple or 5th rib inferiorly, and the apex of the axilla superiorly — centred on the mid-axillary line in the 4th or 5th intercostal space. Insertion should always be over the upper border of the rib to avoid the neurovascular bundle running in the subcostal groove. The 2nd ICS mid-clavicular line is the alternative site for tension pneumothorax needle decompression.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.