Synopsis
Understand how image-guided access, targeted therapy, procedural planning and structured aftercare allow interventional radiology to diagnose and treat disease while controlling bleeding, infection, radiation and organ-injury risks.
- Interventional radiology uses ultrasound, fluoroscopy, CT or MRI to place a needle, wire, catheter or device accurately for diagnosis or treatment through a small access route.
- The clinical question determines both the target and modality: ultrasound gives real-time soft-tissue and vascular guidance without ionising radiation, fluoroscopy follows wires and contrast dynamically, and CT maps deep structures and gas well.
- The Seldinger sequence is needle entry, guidewire passage, needle removal, tract dilation and catheter or sheath placement; wire position must remain controlled throughout every exchange.
Key red flags
New haemodynamic instability, falling haemoglobin, abdominal or back pain, access-site expansion or loss of distal pulses after an intervention requires immediate assessment for occult bleeding or arterial injury.
Fever, rigors, hypotension or worsening organ dysfunction after drain or stent manipulation may represent bacteraemia or sepsis and needs cultures, antimicrobial treatment and source-control review.
Stridor, bronchospasm, facial or tongue swelling, hypoxia or shock after contrast or another procedural medicine is a resuscitation emergency.
New weakness, speech disturbance, visual loss or severe unexpected pain during a vascular procedure raises embolic or ischaemic injury and requires the procedure team to act immediately.
A transpleural route risks pneumothorax, a transhepatic route risks bleeding or bile leak, vascular access risks haematoma and distal ischaemia, and contaminated systems may seed infection; route planning predicts surveillance needs.
Reasoning priorities
Confirm the target, define anatomy and select a route with an acceptable risk-benefit balance.
Assess target size and visibility, intervening bowel or pleura, vessels, collateral supply, access options and signs that the referral question has changed since the scan.
Worked reasoning
A septic patient has hydronephrosis from an obstructing ureteric stone, thrombocytopenia, a distended collecting system on CT and no immediate endoscopic access.
- Identify urgent source control as the objective, resuscitate and give cause-appropriate antimicrobials while urology, radiology and anaesthesia agree that percutaneous nephrostomy is the practical decompression route.
- Review CT and bedside ultrasound for laterality, calyceal dilatation, retrorenal bowel and a feasible posterior calyx; assess platelets, coagulation, antithrombotics and cardiorespiratory tolerance without delaying life-saving drainage unnecessarily.
- Use aseptic technique, local anaesthesia and ultrasound-guided puncture, confirm collecting-system entry with urine and minimal contrast when appropriate, then maintain guidewire control while dilating and placing a locking drain.
- Aspirate a specimen for microbiology, secure and connect the catheter, document urine appearance and output, and give clear flushing, bag, escalation and replacement instructions.
- Verify decompression by clinical improvement and drain function; failure of urine output, worsening sepsis, bleeding or displacement prompts immediate tube and collecting-system assessment rather than assuming technical placement equals source control.
A stable patient is referred for an image-guided diagnostic or therapeutic intervention.