Interventional Radiology Procedures

Interventional radiology (IR) uses image guidance (USG, fluoroscopy, CT, MRI) to perform minimally invasive diagnostic and therapeutic procedures through small percutaneous access points. For NEET PG, the high-yield zone is indications, the correct guidance modality, the access route, and—most of all—complications. This note is built around what gets asked.

Classification of IR procedures

Broadly, IR is divided into vascular (working through the arterial/venous tree via catheters) and non-vascular (percutaneous access into a hollow organ, duct, or solid lesion).

Category	Representative procedures
Diagnostic	Image-guided FNAC, core biopsy, angiography, venous sampling
Drainage	PCN (percutaneous nephrostomy), PTBD (biliary drainage), abscess/pleural/pericardial drainage
Vascular therapeutic	Embolisation, angioplasty/stenting, thrombolysis, IVC filter, TIPS
Tumour-directed	TACE (chemoembolisation), RFA/microwave ablation, cryoablation, Y-90 radioembolisation
Access	Tunnelled central lines, PICC, port insertion, dialysis catheter

High-yield: The two foundational vascular techniques you must know by name are the Seldinger technique (needle → guidewire → remove needle → catheter over wire → remove wire) for vascular access, and the coaxial technique for biopsy (outer guiding needle, inner sampling needle through it for multiple passes via one puncture).

Seldinger flow: Puncture vessel with needle → pass guidewire through needle → remove needle, keep wire → railroad sheath/catheter over wire → remove wire → work through catheter.

Image-guided FNAC and biopsy

The choice of guidance is a classic MCQ.

Lesion / site	Preferred guidance
Superficial, thyroid, breast, lymph node, liver, kidney	Ultrasound (real-time, no radiation, cheap)
Deep retroperitoneal, lung, mediastinum, bone, areas obscured by gas/bone	CT
Breast microcalcifications (impalpable)	Stereotactic mammography-guided
Soft-tissue characterisation (rare for biopsy)	MRI

• FNAC samples cells (cytology) using a fine 22–25 G needle — good for thyroid, lymph node, and confirming metastasis.
• Core needle biopsy (14–18 G, e.g. Tru-cut) gives architecture/histology — needed for lymphoma subtyping, sarcoma grading, and receptor studies.

High-yield: Lung biopsy — the commonest complication is pneumothorax (~25%, fewer than half need a chest tube); next is pulmonary haemorrhage/haemoptysis. Risk rises with deeper lesions, emphysema, and more pleural passes.

High-yield: A phaeochromocytoma should NOT be biopsied (risk of catastrophic hypertensive crisis). Hydatid cyst classically should not be aspirated (anaphylaxis/dissemination), though USG-guided PAIR under albendazole cover is now accepted in selected cysts. Avoid biopsy of vascular lesions (haemangioma, AVM, paraganglioma).

Contraindications to percutaneous biopsy: uncorrectable coagulopathy (INR >1.5, platelets <50,000), no safe access window, uncooperative patient. Hold antiplatelets/anticoagulants per bleeding-risk category.

Percutaneous nephrostomy (PCN)

A nephrostomy tube is placed into the pelvicalyceal system under USG + fluoroscopy guidance.

Indications:

1. Relief of obstructive uropathy (the leading indication) — stone, stricture, pelvic malignancy compressing ureter, especially with obstructed infected system / pyonephrosis (emergency decompression).
2. Urinary diversion for ureteric injury, fistula, or haemorrhagic cystitis.
3. Access for antegrade stenting, PCNL, or stone removal.

High-yield: In obstructed, infected kidney (pyonephrosis) the patient is septic — emergency decompression by PCN is preferred over retrograde stenting, and stone removal is deferred until the infection settles. PCN access for PCNL is classically through a posterior lower-pole calyx (avoids the relatively avascular Brödel's line vessels and reduces colonic injury).

Complications: haemorrhage (most feared significant one — may need embolisation), sepsis, tube dislodgement, pleural injury if access is above the 12th rib, and bowel/visceral injury.

Percutaneous transhepatic biliary drainage (PTBD)

Access into a dilated intrahepatic duct under USG/fluoroscopy to decompress the biliary tree.

Indications: malignant biliary obstruction (cholangiocarcinoma, periampullary/pancreatic head Ca, hilar block) when ERCP fails or is not feasible, acute cholangitis with failed endoscopic drainage, and pre-operative decompression in selected high-bilirubin cases.

High-yield: For distal CBD obstruction, ERCP (retrograde) is first-line; PTBD is reserved for failed ERCP or hilar/proximal blocks where antegrade access is easier. Cholangitis (Charcot's triad: fever + jaundice + RUQ pain) demands urgent drainage.

Complications: sepsis/cholangitis, haemobilia (bleeding into ducts → melaena, jaundice, biliary colic — Quincke's triad), bile leak/peritonitis, and pleural transgression.

Transjugular intrahepatic portosystemic shunt (TIPS)

A stent-shunt created within the liver between a hepatic vein and a portal vein branch via the internal jugular route, decompressing the portal system. A very frequently tested topic.

Indications:

• Refractory/recurrent variceal bleeding not controlled by endoscopy + pharmacotherapy (the classic indication).
• Refractory ascites / hepatic hydrothorax.
• Budd–Chiari syndrome, hepatorenal syndrome (selected).

TIPS access path	Internal jugular vein → SVC/right atrium → hepatic vein → liver parenchyma → portal vein
Aim of shunt	Reduce portosystemic gradient to < 12 mmHg (target gradient that prevents variceal rebleeding)

High-yield: The most important complication and a favourite MCQ answer is new-onset or worsening hepatic encephalopathy (~20–30%) because blood bypasses the detoxifying liver. Other issues: shunt stenosis/thrombosis, worsening hepatic function/liver failure, and haemolysis.

High-yield: Absolute contraindications to TIPS include severe right heart failure / pulmonary hypertension (the shunt increases venous return and preload), severe hepatic failure, polycystic liver disease, and uncontrolled sepsis. Pre-existing encephalopathy is a (relative) contraindication.

Embolisation

Therapeutic occlusion of a vessel by delivering an agent through a catheter. Two big buckets: stop bleeding and starve a lesion.

Embolic agent	Type / typical use
Gelfoam (gelatin sponge)	Temporary, recanalises in weeks — trauma/acute bleed
Coils	Permanent, mechanical — pseudoaneurysm, GI bleed, varicocele
PVA particles / microspheres	Permanent, small-vessel — fibroids (UAE), tumours
Glue (NBCA), Onyx (EVOH)	Liquid — AVM, high-flow lesions
Drug-eluting/lipiodol + chemo	TACE for hepatocellular carcinoma

Indications: GI bleeding (after failed endoscopy), post-partum haemorrhage, trauma (splenic/hepatic/pelvic), haemoptysis (bronchial artery embolisation), uterine artery embolisation (UAE) for fibroids, varicocele, epistaxis, pre-operative devascularisation (renal Ca, meningioma), and pulmonary AVM.

High-yield: Bronchial artery embolisation is the treatment of choice for massive/recurrent haemoptysis (commonest cause in India: post-tubercular bronchiectasis/aspergilloma). Feared complication: spinal cord ischaemia / transverse myelitis if the anterior spinal artery (artery of Adamkiewicz) arises from a bronchial/intercostal trunk and is inadvertently embolised.

High-yield: Post-embolisation syndrome (fever, pain, nausea, leucocytosis) after TACE/UAE is self-limiting and managed supportively — do not mistake it for sepsis or abscess.

High-yield: Splenic artery embolisation carries a risk of splenic abscess and overwhelming post-splenectomy infection (OPSI) physiology — vaccination considerations apply with significant infarction. UAE is contraindicated in women desiring future fertility (relative) and in pregnancy/active infection.

Thrombolysis — principles

Catheter-directed thrombolysis (CDT) delivers a thrombolytic (alteplase/rt-PA, urokinase) directly into the clot through a multi-side-hole catheter — higher local concentration, lower systemic dose and bleeding than IV thrombolysis.

Indications: acute limb ischaemia (Rutherford IIa/early IIb), extensive iliofemoral DVT in young patients (to prevent post-thrombotic syndrome), and selected massive PE/dialysis-graft thrombosis.

High-yield: Mechanism — thrombolytics convert plasminogen → plasmin, which lyses fibrin. The dreaded complication is major haemorrhage, particularly intracranial bleed. Absolute contraindications: recent intracranial haemorrhage/stroke, active bleeding, recent major surgery/trauma, intracranial neoplasm.

Contrast media and reactions

Iodinated contrast is central to IR. Low-osmolar non-ionic agents (iohexol, iopamidol) have largely replaced high-osmolar ionic agents because they cause far fewer reactions.

Types of reaction:

1. Anaphylactoid (idiosyncratic): not dose-dependent, not true IgE allergy. Urticaria → bronchospasm → laryngeal oedema → hypotension/shock.
2. Physiological (chemotoxic): dose/concentration related — warmth, flushing, nausea, vasovagal bradycardia, arrhythmia.
3. Delayed: rash hours–days later.

Severity	Features	Management
Mild	Limited urticaria, nausea, flushing	Observe, reassure; oral antihistamine
Moderate	Diffuse urticaria, mild bronchospasm, facial oedema	Antihistamine, salbutamol, IV fluids, O₂
Severe	Laryngeal oedema, severe bronchospasm, hypotension, shock	Adrenaline (1:1000) 0.3–0.5 mg IM, O₂, IV fluids, call for help

High-yield: The single most important drug for a severe contrast anaphylactoid reaction is adrenaline IM. For an isolated vasovagal reaction (hypotension + bradycardia), the drug is atropine plus leg elevation and fluids — distinguishing brady- (vasovagal) from tachycardia (anaphylactoid) drives the answer.

High-yield: Contrast-induced nephropathy (CIN) — rise in creatinine ≥0.5 mg/dL or ≥25% within 48–72 h. Highest risk: pre-existing renal impairment + diabetic nephropathy. Prevention is IV isotonic saline hydration (best evidence); contrast minimisation; stop nephrotoxins. Metformin is withheld around contrast in renal impairment (lactic-acidosis risk, not CIN itself).

High-yield: NSF (nephrogenic systemic fibrosis) is linked to gadolinium in severe renal failure (eGFR <30) — avoid high-risk linear gadolinium agents. A premedication regimen (corticosteroid + antihistamine, e.g. prednisolone at 13/7/1 h before) is used for patients with prior moderate/severe reactions.

Complications overview

Procedure	Most-tested complication
Lung biopsy	Pneumothorax
PCN	Haemorrhage / sepsis
PTBD	Haemobilia, sepsis
TIPS	Hepatic encephalopathy
Bronchial artery embolisation	Spinal cord ischaemia
TACE / UAE	Post-embolisation syndrome
Thrombolysis	Major / intracranial bleed
Contrast	Anaphylactoid reaction, CIN

Key differentials / "which procedure" decision points

• Distal CBD malignant obstruction → ERCP first; PTBD only if ERCP fails or block is hilar.
• Obstructed infected kidney → PCN decompression (not immediate stone removal).
• Massive haemoptysis → bronchial artery embolisation (not surgery first).
• Refractory variceal bleed → TIPS (after endoscopic + drug failure).
• Symptomatic fibroid, fertility not desired → UAE; fertility desired → myomectomy.
• Small HCC, not resectable, Child A/B → ablation (RFA) for ≤3 cm; TACE for larger/multifocal intermediate-stage.

Recently asked / exam angle

• Seldinger vs coaxial technique — match technique to vascular access vs biopsy.
• Drug of choice in severe contrast reaction (adrenaline IM) and vasovagal reaction (atropine) — recurring single-best-answer.
• Commonest complication of percutaneous lung biopsy (pneumothorax).
• Commonest/most significant complication of TIPS (hepatic encephalopathy) and its contraindications (right heart failure/pulmonary HTN).
• Treatment of choice for massive haemoptysis (BAE) and its spinal-cord ischaemia risk.
• Definition and prevention of contrast-induced nephropathy; metformin withholding rule; gadolinium–NSF link.
• Embolic agent matching (Gelfoam = temporary; coils/PVA = permanent).
• Best access calyx for PCNL (posterior lower pole).
• Lesions you must NOT biopsy (phaeochromocytoma, hydatid, vascular lesions).
• Image-guidance MCQs: USG for thyroid/liver/breast, CT for lung/retroperitoneum, stereotactic for breast microcalcification.

Rapid revision

1. Seldinger = vascular access (needle→wire→catheter); coaxial = single-puncture multi-pass biopsy.
2. USG for superficial/thyroid/liver/kidney; CT for lung, mediastinum, retroperitoneum, bone.
3. Lung biopsy → commonest complication pneumothorax.
4. Never biopsy a phaeochromocytoma or hydatid cyst (crisis/anaphylaxis).
5. PCN is emergency decompression for obstructed infected kidney (pyonephrosis).
6. PCNL access via posterior lower-pole calyx.
7. ERCP first for distal CBD block; PTBD for failed ERCP / hilar block.
8. TIPS = jugular → hepatic vein → portal vein; target gradient < 12 mmHg; commonest complication hepatic encephalopathy; contraindicated in right heart failure.
9. Gelfoam = temporary, coils/PVA = permanent embolic agents.
10. Bronchial artery embolisation for massive haemoptysis; risk spinal cord ischaemia (artery of Adamkiewicz).
11. Severe contrast reaction → adrenaline IM; vasovagal → atropine.
12. CIN = creatinine rise within 48–72 h; prevent with IV saline hydration; withhold metformin; gadolinium causes NSF in eGFR <30.