Genitourinary · IR Playbook

Percutaneous Nephrostomy Placement and Catheter Management (PCN)

Percutaneous nephrostomy is image-guided placement of a catheter into the renal collecting system for urinary decompression, diversion, or access for subsequent therapy. It is the procedure of choice for urgent decompression of an infected obstructed kidney when retrograde drainage is unsuitable or unavailable. Technical success is approximately 82–99% in obstructed systems and 98% in pyonephrosis; important risks include sepsis, haemorrhage, adjacent-organ injury, catheter occlusion, and dislodgement.

Learning objectives

• Select appropriate indications and urgency for percutaneous nephrostomy.
• Plan a safe direct calyceal puncture using ultrasound and cross-sectional imaging.
• Perform micropuncture access, tract dilatation, and locking pigtail catheter placement.
• Minimise haemorrhagic and septic complications, particularly in pyonephrosis.
• Manage catheter blockage, leakage, dislodgement, routine exchange, and removal.

Indications

• Urgent decompression of an infected obstructed collecting system or pyonephrosis.
• Obstructive uropathy causing acute kidney injury, progressive renal impairment, uncontrolled pain, or obstruction of a solitary functioning or transplanted kidney.
• Urinary diversion for ureteric or collecting-system leakage, urinary fistula, or severe haemorrhagic cystitis.
• Access for percutaneous nephrolithotomy, antegrade ureteric stenting, ureteric intervention, foreign-body retrieval, or urothelial biopsy.
• Access for upper-tract instillation of antifungal agents or chemotherapy.
• Decompression to preserve renal function before chemotherapy or definitive urological treatment.

Relative contraindications

• Severe uncorrected coagulopathy or thrombocytopenia when retrograde drainage is feasible; pyonephrosis requiring life-saving drainage should not be delayed solely to achieve perfect laboratory values.
• Severe hyperkalaemia greater than 6 mEq/L or metabolic acidaemia with pH below 7.2 until nephrology-assisted stabilisation when clinically possible.
• Absence of a safe percutaneous route because of retrorenal colon, interposed pleura, liver, spleen, major vessels, or other viscera.
• Inability to tolerate positioning or remain still without anaesthetic support.
• Advanced malignant obstruction in which external drainage is unlikely to improve symptoms, renal function, treatment eligibility, or quality of life.

Equipment

• Ultrasound machine with curvilinear transducer, sterile probe cover, colour Doppler, and needle guide if preferred.
• Fluoroscopy unit with low-dose pulsed fluoroscopy and last-image hold.
• Sterile nephrostomy tray, drapes, chlorhexidine skin preparation, scalpel, syringes, and local anaesthetic such as 1% lignocaine.
• 21 G two-part access needle or micropuncture needle with 0.018-inch nitinol-tipped guidewire.
• Alternative 16–19 G access needle for experienced operators or a scarred fibrotic renal cortex requiring direct 0.035-inch wire access.
• Micropuncture or triaxial access set for conversion from a 0.018-inch wire to a 0.035-inch or 0.038-inch system.
• 0.035-inch hydrophilic guidewire and 0.035-inch stiff working guidewire with atraumatic tip.
• 4–6 Fr angled diagnostic catheter when wire direction into the renal pelvis requires assistance.
• Fascial dilators sized to the selected catheter, with availability of a dilator 1 Fr larger for a fibrotic tract.
• 8–10 Fr locking pigtail nephrostomy catheter; consider 10–12 Fr drainage for thick pus, clot, or anticipated prolonged drainage.
• Dilute non-ionic iodinated contrast, tubing, sterile urine specimen container, drainage bag, catheter securement device, and sterile dressing.
• Resuscitation medications, vasopressors, oxygen, suction, and equipment for management of urosepsis or sedation-related deterioration.

Procedure steps

1. Perform a time-out confirming the side, indication, urgency, imaging, coagulation status, antibiotics, and intended future intervention. Review the safest calyx and whether an interpolar tract is required for later stenting.
2. Position the patient prone, semi-prone, or decubitus and perform immediate ultrasound with colour Doppler. Mark a posterolateral route that avoids bowel, pleura, solid organs, vessels, and erector spinae muscle.Pearl: Repeat the ultrasound after final positioning because renal position and the access window change with rotation and respiration.
3. Prepare a wide sterile field and infiltrate local anaesthetic into the skin, subcutaneous tissues, muscular tract, and renal capsule. Make a small skin incision after anaesthesia is effective.
4. During suspended respiration, advance a 21 G needle under real-time ultrasound into the selected posterior calyx through renal parenchyma. Use a direct calyceal puncture rather than first puncturing the renal pelvis.Pearl: A small pop may be felt as the needle enters the collecting system; targeting the calyceal fornix provides a stable parenchymal tract.
5. Remove the stylet and aspirate urine or pus, sending a sterile specimen for culture in suspected infection. In pyonephrosis, decompress by aspiration and avoid routine contrast injection or unnecessary manipulation.
6. Advance the 0.018-inch wire through the needle and coil it securely within the renal pelvis or direct it down the ureter when feasible. Confirm smooth intraluminal movement under fluoroscopy without forcing the wire.Pearl: Obtain a generous wire purchase before exchanging the needle because a newly decompressed collecting system can rapidly collapse.
7. Advance the micropuncture or triaxial set over the 0.018-inch wire and exchange for a 0.035-inch stiff working wire. Maintain continuous control of the wire and catheter hub during every exchange.
8. Sequentially dilate the tract to the diameter required for the nephrostomy catheter. In a scarred or fibrotic cortex, dilatation to 1 Fr larger than the planned catheter may be necessary.Pearl: Keep the wire tip coiled safely within the collecting system while advancing each dilator.
9. Advance an 8–10 Fr locking pigtail catheter over the wire, position all side holes within the collecting system, and form the loop in the renal pelvis. Use a larger catheter when thick pus or clot is likely to obstruct a small lumen.
10. Confirm free urine drainage and satisfactory loop position. If the system is not infected, a small gentle contrast injection may document catheter position and the obstruction; omit unnecessary nephrostography in pyonephrosis.Pearl: Successful drainage and an entirely intrapelvic catheter are more important than producing a complete diagnostic pyelogram.
11. Lock the pigtail, secure the catheter using a stabilisation device and sterile dressing, and connect it to gravity drainage. Record catheter type, size, side-hole position, aspirate appearance, specimen collection, contrast volume, and planned management.

Complications

• Haemorrhage requiring transfusion, approximately 1.9–4%
• Urosepsis or septic shock, approximately 7–9% in pyonephrosis
• Non-target organ or pleural injury, approximately 0.1–0.2%
• Catheter occlusion, approximately 1.7% requiring exchange
• Catheter dislodgement, approximately 3.6–5% during the first month
• Post-obstructive diuresis

Exam pearls

• An infected obstructed kidney is a drainage emergency; antibiotics alone are inadequate source control.
• Direct posterior calyceal puncture through the relatively hypovascular plane of Brödel is preferred.
• Use an interpolar calyx when antegrade ureteric stenting is anticipated.
• Never perform forceful pyelography in pyonephrosis because increased intrapelvic pressure can precipitate septic shock.
• Persistent severe haematuria beyond 3 days suggests arterial injury and requires CT angiography followed by angiography and embolisation when indicated.
• Routine long-term PCN exchange begins at 6–8 weeks and may be extended to 8–12 weeks if encrustation is minimal.

Viva questions

What are the principal indications for percutaneous nephrostomy?

The major categories are urinary drainage for obstruction or pyonephrosis, urinary diversion for leaks or fistulae, access for interventions such as PCNL or antegrade stenting, and access for upper-tract medication instillation.

Why should the renal pelvis not be punctured directly?

A direct calyceal puncture traverses renal parenchyma, which provides catheter stability and tract tamponade. Direct pelvic or infundibular puncture is associated with greater vascular injury, bleeding, and urine leakage.

What is the preferred calyx for a drainage nephrostomy and for future antegrade stenting?

A posterior lower-pole or interpolar calyx is suitable for routine drainage. An interpolar calyx is preferred when antegrade ureteric stenting is anticipated because it provides a more favourable angle toward the ureter.

Why should contrast injection be minimised in pyonephrosis?

Contrast injection raises collecting-system pressure and can force infected urine or bacteria into the circulation, precipitating bacteraemia and septic shock. Aspirate first and perform only the manipulation required to establish safe drainage.

What coagulation parameters are generally acceptable before elective nephrostomy?

A practical target is platelet count at least 50,000 per microlitre, INR 1.5 or less, prothrombin time approximately 15 seconds or less, and haemoglobin above 8 g/dL. Clinical bleeding history and anticoagulant pharmacology remain important because laboratory tests alone do not measure all bleeding risks.

How do you manage persistent haematuria after nephrostomy?

Assess haemodynamics, haemoglobin, coagulation, and catheter position while keeping the catheter in place. Persistent severe haematuria beyond 3 days, or earlier instability, requires CT angiography and usually renal angiography with selective embolisation if arterial injury is found.

What is the routine nephrostomy exchange interval?

Exchange every 6–8 weeks initially and extend to 8–12 weeks when repeated exchanges show minimal encrustation. Pregnancy generally requires exchange every 4–6 weeks.

How should a dislodged nephrostomy catheter be managed?

Do not blindly reinsert or advance it. Arrange urgent fluoroscopic tract salvage using a hydrophilic wire or perform a new puncture, with greater urgency in infection, a solitary kidney, or complete obstruction.

References