Percutaneous nephrostomy

Percutaneous nephrostomy is a form of nephrostomy in which percutaneous access to the kidney is achieved under radiological guidance. The access is then often maintained with the use of an indwelling catheter.

Indications

Percutaneous nephrostomy is usually reserved for when retrograde approaches are unsuccessful or difficult. Clinical settings include:

• urinary tract obstruction
• urinary diversion (e.g. ureteric injury; urine leak)
• access for percutaneous procedures (e.g. stone treatment; antegrade ureteric stenting)
• diagnostic testing (e.g. antegrade pyelography, Whitaker test) ⁶

Contraindications

Absolute contraindications

• usually none

Relative contraindications

• uncorrectable bleeding diathesis (abnormal coagulation indices)
• uncooperative patient
• severe respiratory disease
• uncorrected severe hyperkalaemia and/or metabolic acidosis
  • urgent haemodialysis can correct metabolic derangement before nephrostomy insertion ⁶

Procedure

Preprocedure evaluation

• review all available imaging to confirm the indication for the procedure and assess renal anatomy and establish safe access route to the kidney
• check full blood count and coagulation profile to assess the risk of haemorrhage
• obtain informed consent for the procedure
• obtain good peripheral IV access
• administer broad-spectrum IV antibiotics 1-4 hours prior to the procedure, if needed; septic patients are often already on parenteral antibiotics

Positioning

The procedure is performed with the patient in prone, prone oblique or lateral position, depending on clinical circumstances and patient comfort. Regular monitoring of the vital signs by a suitably trained staff member is recommended during the procedure. Clean skin with antiseptic solution and drape to maintain sterility for the procedure.

Equipment

• ultrasound or fluoroscopy guidance
• local anaesthesia with 1% or 2% lidocaine
• 18 gauge puncture needle, an alternative would be to use micropuncture set with a 21 or 22 gauge needle
• 0.035 inch stiff guidewire (an 0.018 guidewire is also used with a micropuncture set)
• water-soluble contrast media
• dilators ranging from 7-9 French
• pigtail drain (typically 8 French)

Medications

• prophylactic antibiotics - typically a 3^rd generation cephalosporin in selected patients, antibiotic use is not routine ³
• analgesia (e.g. pethidine; fentanyl) - not routinely used, but can aid in co-operation in selected patients
• sedation - a short-acting benzodiazepine (e.g. midazolam) may be used in selected patients

Technique

Two common techniques exist. The choice of technique depends on both operator and patient factors. One method uses a two- or three-part puncture needle and the other a micropuncture kit.

Using aseptic technique and following infiltration of local anaesthetic agent, the calyx (usually posterior calyx at the mid or lower pole) is punctured with an 18 gauge, two-part needle under ultrasound guidance. In the presence of renal tract obstruction, urine drains freely on the removal of the stylet from the needle. A small volume of water-soluble contrast material can be injected to confirm correct needle position using fluoroscopy. A 0.035 guidewire is used to exchange the needle for a dilator and typically an 8 French pigtail drain is placed within the renal pelvis over the guidewire. On occasion, a 6F or 12F catheter may be used, on an individual case basis. A urine sample can be sent off to the laboratory for microbiological studies. The catheter is left to drain freely.

Postprocedural care

Bed rest (typically 2-4 hours) with regular monitoring of vital signs, provision of adequate analgesia are routinely indicated in the first few hours following the procedure. Fluid balance is regularly monitored, particularly in cases of urinary tract obstruction. Indwelling nephrostomy catheters are usually exchanged every three months ^4,6.

It is normal for the urine to be partly blood-stained for the first 48-72 hours ⁵.

The patient should take great care with the nephrostomy tube, to avoid malpositioning, despite the internal pigtail of the locked drain, skin anchoring stitch and adhesive plaster. Slippage is not uncommon but if alerted to medical staff early, nephrostomy salvage can be performed without re-puncture.

Adequate hydration can prevent early nephrostomy encrustation and obstruction. Nephrostomy exchanges every 3 months are usually recommended.

Complications

• bleeding
• pneumothorax
• bowel injury and peritonitis
• urine leak
• splenic or liver injury
• catheter encrustation and obstruction
• catheter displacement - reported at ~20% after a few months ⁶

History and Etymology

Goodwin et al first described the technique of percutaneous nephrostomy in 1955 ⁷.