Interventional Radiology: Core Principles, Safety, and Exam Traps
Scope of the IR Section
Interventional radiology questions test procedural decision-making, periprocedural pharmacology, device and technique selection, and complication recognition. Organize study around four pillars: (1) pre-procedure assessment, (2) image-guided access and navigation, (3) embolic/occlusive and revascularization techniques, and (4) periprocedural management and complications.
Pre-Procedure Fundamentals
Know coagulopathy thresholds and when correction is warranted; know contrast allergy premedication regimens and when to substitute CO2 or gadolinium; know renal-protection strategies (hydration, minimizing volume, avoiding nephrotoxins). Recognize that most periprocedural antibiotics are indicated only for specific scenarios (e.g., biliary intervention, solid-organ embolization, certain drains), not universally.
Technique Concepts
Understand the difference between embolic agents: coils (large-vessel occlusion), particles (capillary-level, tumor/devascularization), gelatin sponge (temporary, mid-vessel), liquid embolics (definitive, distal). Know access-site management, closure devices, and retroperitoneal hemorrhage recognition. For venous access, distinguish tunneled vs non-tunneled catheters, port types, and appropriate tip position (cavoatrial junction). For biliary and urinary interventions, know indications for drainage vs stenting and the significance of cholangitis.
Common Traps
Questions often hinge on the next best step rather than the definitive diagnosis. Watch for: confusing prophylactic with therapeutic antibiotics; assuming every coagulopathic patient needs correction; misidentifying which vessel requires embolization; and overlooking post-embolization syndrome (fever, pain, leukocytosis) as a benign, expected finding rather than infection.
Rule of thumb: For any IR scenario, ask: Is the patient unstable? If yes, resuscitate and control the source first. If stable, choose the least invasive definitive option and confirm with imaging.
Worked example: A patient with hemoptysis and a bleeding bronchial artery on angiography - the answer is bronchial artery embolization with particles/coils, not systemic vasopressors alone, because vasopressors may worsen the underlying cause and do not definitively control the bleed.