Puncture a posterior lower- or mid-pole calyx under ultrasound, along the relatively avascular plane (Brödel line), then confirm with contrast before the guidewire and catheter — never the renal pelvis directly.
Orient first
- Indications: infected obstructed kidney (emergency), relief of obstruction, access for stone or ureteric work.
- Posterior calyces lie about 20–30° behind the frontal plane; a direct pelvic puncture risks major vessels.
- Correct coagulopathy; antibiotic cover; decompress an infected system with minimal contrast.
Acquire the study
- Prone or prone-oblique position; ultrasound-guided needle puncture; fluoroscopic confirmation with pulsed fluoroscopy and collimation.
The manoeuvre
- Degree of hydronephrosis and the target posterior calyx; skin-to-calyx depth in cm.
- Colour Doppler along the needle path: avoid interlobar vessels.
- Needle tip in the calyx; aspirate urine (send for culture) before injecting contrast.
What confirms it
- Catheter pigtail in the collecting system with drainage of urine.
What licenses you to exclude it
- Not applicable — a procedure; record complications (haematuria, perinephric haematoma, sepsis).
The classic misread
- Puncturing the renal pelvis directly.
- Over-distending an infected system with contrast and precipitating sepsis.