Contrast injection into an obstructed system is itself a risk — opacify sparingly, decompress first, and read the level from the filling pattern.
Orient first
- Injecting contrast into an OBSTRUCTED biliary system raises intraductal pressure and can precipitate cholangitis and septic shock. The rule is to ASPIRATE before injecting and to opacify only as much as is needed to define the anatomy.
- A duct that fills but does not drain is the dangerous combination — contrast that cannot escape maintains the raised pressure after the procedure.
- The LEVEL and the pattern of filling name the obstruction: an abrupt cut-off suggests malignancy, a tapered narrowing suggests a benign stricture, and a mobile rounded filling defect suggests a stone.
- In a hilar obstruction, opacifying a duct you then cannot drain converts an undrained but sterile segment into an infected one. Plan which sector to enter before injecting.
- Air and contrast look different and behave differently — air rises, contrast falls — and using that during positioning helps confirm which duct has been entered.
Acquire the study
- Review the cross-sectional imaging first and decide the target duct BEFORE any needle goes in — the fluoroscopic run is not the planning study.
- Antibiotic cover and correction of coagulopathy before the procedure.
- Collimate tightly and use pulsed fluoroscopy with the lowest adequate frame rate; store fluoroscopy rather than taking extra acquisitions.
- Aspirate bile before injecting contrast, and send it for culture.
The manoeuvre
- Confirm the needle position by aspirating bile before any injection.
- Inject contrast SPARINGLY under live fluoroscopy and watch the filling pattern rather than filling the whole tree.
- Identify the level at which contrast stops and describe the shape of that transition: abrupt, tapered, or a filling defect.
- Rotate the patient or the C-arm to separate overlapping ducts before committing to a sector.
- Confirm the guidewire passes the obstruction where a stent is planned, and record the length of the stricture.
- After drain placement, inject a small volume to confirm position and free drainage into bowel or into the bag.
- Record the final catheter position, its side holes relative to the obstruction, and the fluoroscopy time and dose.
What confirms it
- Correct placement is bile aspirating freely, contrast draining away from the ducts, and the catheter side holes sited above and, where crossed, below the obstruction.
What licenses you to exclude it
- ⚠️ A duct that opacifies is not a duct that drains. Confirm drainage rather than inferring it from a good-looking cholangiogram.
- A non-opacified sector is not a normal sector — it may simply be isolated, and in hilar obstruction that is the segment most likely to become infected.
The classic misread
- Injecting a full cholangiogram into an obstructed system before decompressing it.
- Opacifying a sector that cannot then be drained.
- Confusing air with contrast when confirming duct entry.
- Reporting position without confirming free drainage.