Percutaneous nephrostomy

Percutaneous nephrostomy is a technique 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.

Procedure
Pre-procedure 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 machine or fluoroscopy
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
0.38 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 3rd 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 utlilises a two- or three-part puncture needle and the other a micro-puncture 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 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 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, 7.

It is essentially 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 mal-positioning, 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.

Complications
bleeding
pneumothorax
bowel injury and peritonitis
urine lea
catheter displacement - reported at ~20% after a few months

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