Interventional and Point-of-Care Ultrasound
Interventional and Point-of-Care Ultrasound tests procedural safety and real-time image interpretation under time pressure. You must know the pre-procedure checklist, the geometry of needle guidance, and the limits of each POCUS sign.
Core rules
- Pre-procedure: confirm indication, obtain consent, review anticoagulation and coagulation (commonly INR ≤1.5 and platelets ≥50 ×10⁹/L), perform a time-out, and use full sterile technique for deep procedures.
- In-plane guidance shows the needle shaft and tip along its length; out-of-plane shows a dot, so confirm the tip by moving the probe or injecting a small amount of fluid.
- Always identify the needle tip, not just the shaft, and keep it in view throughout the pass.
- eFAST examines Morison's pouch, splenorenal recess, pelvis and pleural spaces.
- Lung ultrasound: absent sliding plus a stratosphere (barcode) sign on M-mode suggests pneumothorax; a lung point is specific.
- IVC diameter and collapsibility, plus cardiac views, inform volume status.
Worked example
A dyspneic patient has absent lung sliding on the right, a stratosphere sign on M-mode, and a transition to normal sliding laterally - a lung point. Absent sliding alone can reflect apnea, adhesions or mainstem intubation, but the lung point is highly specific, so pneumothorax is diagnosed and decompression is considered. Note that B-lines would have argued against pneumothorax in that zone.
Traps that cost marks
Using Doppler to locate the needle tip; trusting an out-of-plane dot as the tip; excluding pneumothorax from B-lines alone; and skipping documentation of the approach, needle gauge and post-procedure imaging.