Percutaneous nephrostomy ("a minima" technique) with ultrasound guidance

Percutaneous nephrostomy “a minima” is a minimally invasive procedure performed under ultrasound guidance to create an external drainage of the renal pelvicalyceal system, using a thin nephrostomy catheter, minimizing tissue trauma and reducing complication risks.

Role

• Emergency urinary decompression in ureteral obstruction.
• Treatment of obstructive pyelonephritis and urosepsis.
• Preserving renal function by reducing pressure in the pelvicalyceal system.
• Creating access for subsequent urological procedures (percutaneous nephrolithotomy, ureteroscopy, ureteral stent).
• Drainage of urinary fistulas or urine extravasation.

Advantages

• Minimally invasive, quick, and well-tolerated.
• Reduced risk of complications compared to classical techniques.
• Can be performed emergently or electively.
• Short procedure duration (15–30 minutes on average).

Indications

• Ureteral obstruction (stones, strictures, tumors).
• Infected obstruction / urosepsis, anuria.
• Hydronephrosis, pain caused by urinary obstruction.
• Urinary fistulas or urine extravasation.
• Impossibility to place a ureteral stent.
• Need for access for further procedures.

Contraindications

• Absolute: Severe uncorrectable coagulopathy; skin infection or abscess at puncture site.

• Relative: Renal vascular tumors; ectopic kidney or significant anatomical anomalies (alternative guidance may be required).

Procedure

• Performed under ultrasound guidance in sterile conditions, patient usually prone.
• After local anesthesia, a dilated calyx of the pelvicalyceal system is punctured and urine aspiration confirms needle placement.
• A guidewire is introduced, minimal dilation performed, then a thin nephrostomy catheter (“a minima”) is placed.
• The catheter is fixed to the skin and connected to the drainage system.

Outcome

• Restoration of urinary flow.
• Reduction of pressure in the pelvicalyceal system.
• Access for potential further interventions.