**4.2 First time insertion PF stent**

The procedure for insertion involves three steps:


*Step 1* 

For unilateral placement, the patient is positioned in the Lloyd-Davis position, with the ipsilateral leg in extension and the affected side elevated to approximately 200 with 3 litre saline bags. Gram-negative antibiotic prophylaxis is given – usually Gentamicin 2mg/Kg. The skin is prepared with aqueous iodine and draping applied to leave the abdomen and nephrostomy tube exposed (Fig. 3). The C-arm is positioned at the opposite side of the stent insertion while the camera with stack is placed near the foot of the table opposite the operator. An assistant needs to be able to perform a cystoscopy at the same time the operator places the upper end of the stent as detailed below.

Ideally the patient already has a nephrostomy tube in place and thus the following steps are undertaken. However, it is possible to create a new track and deliver the proximal end of the stent into the kidney de-novo. Local anaesthetic is injected into the skin around the nephrostomy tube and contrast is injected to opacify the collecting system. A 0.38F Sensor guide wire (Microvasive) is passed through the existing nephrostomy tube and the tube removed under screening leaving the wire in the system. The tapered end of the EAS is placed into the collecting system over the wire producing a good coil in the kidney. The skin incision is extended in a transverse direction for 2cm and the existing cutaneous aspect of the existing fistulous track is excised and dissected free from the rest of the tract in order to allow the stent to sit below the skin cutaneous margin (Fig. 4).

Extra-Anatomic Urinary Drainage for Urinary Obstruction 287

Fig. 5. The Alken dilators used to create a subcutaneous tunnel down to the supra-pubic

The site of the last skin incision should be in the supra-pubic region but lateral to the midline. An assistant performs a cystoscopy to allow visualization of the stent as it is inserted into the bladder using a modified Seldinger technique with the aid of a 12 F peelaway sheath. Before the stent is finally delivered into its final subcutaneous tunnel the position of proximal end of the stent is checked with x ray screening (Fig. 6). The presence of a cystoscope should prevent distal stent migration out through the urethra. The skin is

Stents are changed routinely at 12 months (although licensed for 3 months), using the

A clip is used to identify a suitable position to incise the skin anteriorly, ideally half way along the stent but any position proximal to the bladder is acceptable. It is better to be able to see this site and the proximal coil in the kidney in the same fluoroscopic image. Making a small transverse incision at the appropriate site exposes the stent. The stent is then cut and a Sensor guide-wire passed through the proximal portion of the stent, which is then removed. The new stent is passed over the guide-wire before withdrawing the wire. The guide-wire is then passed into the bladder via the distal end of the old stent, which is then removed. The distal end of the new stent is passed over the wire into the bladder and the guide-wire

removed endoscopically from the distal end of the stent (Minhas et al., 1999).

region.

*Step 3* 

closed with absorbable sutures and skin glue.

**4.3 Exchange of PF stent**

following technique:

Fig. 3. Patient positioning over the edge of the operating table with fluid bags elevating the side and the nephrostomy tube included in skin preparation.

Fig. 4. The Paterson-Forrester extra-anatomic stent is passed over a guide wire and replaces the nephrostomy tube. The skin bridge is dissected free.

*Step 2* 

The Alken PCNL coaxial metal dilators are used to create a multi-stage subcutaneous tunnel (Fig. 5). The 9F long metal guide rod is passed in the subcutaneous fat layer obliquely towards the iliac fossa. The tract is sequentially dilated to 18F. After injection with local anaesthetic the skin is incised over the tip of the dilators at a point that allows control of both ends of the dilators. The smaller dilators are retrieved from the new incision leaving only the 18F dilator in place through which the EAS is passed towards the bladder. The metal dilator is then retrieved distally leaving the stent in a new subcutaneous tunnel. The procedure is repeated two or three times depending upon the route taken to the supra-pubic area avoiding scars and or stomas.

Fig. 5. The Alken dilators used to create a subcutaneous tunnel down to the supra-pubic region.

*Step 3* 

286 Chronic Kidney Disease

Fig. 3. Patient positioning over the edge of the operating table with fluid bags elevating the

Fig. 4. The Paterson-Forrester extra-anatomic stent is passed over a guide wire and replaces

The Alken PCNL coaxial metal dilators are used to create a multi-stage subcutaneous tunnel (Fig. 5). The 9F long metal guide rod is passed in the subcutaneous fat layer obliquely towards the iliac fossa. The tract is sequentially dilated to 18F. After injection with local anaesthetic the skin is incised over the tip of the dilators at a point that allows control of both ends of the dilators. The smaller dilators are retrieved from the new incision leaving only the 18F dilator in place through which the EAS is passed towards the bladder. The metal dilator is then retrieved distally leaving the stent in a new subcutaneous tunnel. The procedure is repeated two or three times depending upon the route taken to the supra-pubic

side and the nephrostomy tube included in skin preparation.

the nephrostomy tube. The skin bridge is dissected free.

area avoiding scars and or stomas.

*Step 2* 

The site of the last skin incision should be in the supra-pubic region but lateral to the midline. An assistant performs a cystoscopy to allow visualization of the stent as it is inserted into the bladder using a modified Seldinger technique with the aid of a 12 F peelaway sheath. Before the stent is finally delivered into its final subcutaneous tunnel the position of proximal end of the stent is checked with x ray screening (Fig. 6). The presence of a cystoscope should prevent distal stent migration out through the urethra. The skin is closed with absorbable sutures and skin glue.
