**3. Stents**

Different types of EAS have been developed and used successfully by different authors (Lingam, 1994; Minhas, 1999; Desgrandchamps, 1998a;, Lloyd, 2007). The designs have varied with the materials used, length of stent, diameter of stent and on whether one or composite stent/s are utilized. They however, all have a common objective of establishing a

Extra-Anatomic Urinary Drainage for Urinary Obstruction 285

Percutaneous nephrostomy track placement tray with telescopic metal dilators to size 3 (18F).

1. Insertion of stent in the kidney via a new or existing nephrostomy tract. Our preferred option is to use the track of an existing nephrostomy tube after a minimum of 5 days

2. Creation of a subcutaneous tunnel and tunneling of the stent to reach the supra-pubic

3. Creation of a supra-pubic tube cystostomy and insertion into the bladder in the bladder.

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

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

Contrast solution in a luer lock syringe

Needle holder and absorbable sutures Nephrostomy needle and 0.38F j tip wire

*Extra equipment for exchange of stent*  6F end flushing ureteric catheter

**4.2 First time insertion PF stent** 

Dissecting scissors

12 F peel away sheath

insertion.

region.

*Step 1* 

Minor operation tray with scalpel, tissue forceps and clips

0.38F floppy tip stiff core Sensor wire (Microvasive)

The procedure for insertion involves three steps:

operator places the upper end of the stent as detailed below.

allow the stent to sit below the skin cutaneous margin (Fig. 4).

Flexible rat-toothed stent removing forceps if flexible cystoscope is used

Fig. 2. Tumour invasion along the route of an extra-anatomic stent.

nephro-vesical subcutaneous urinary diversion. The diameter of the stent is thought to be the main determinant of the duration the stent may remain in situ without encrustation or blocking. It has been estimated that a 17 F diameter is required to prevent stent encrustation irrespective of its composition in association with increased fluid intake (Andonian, et al. 2005).

To this end, we utilize two types of stents in our practice. One is a short-term 8.5F 65cm EAS without side holes except at either end. We offer to all patients with malignant disease and in patients with poor general health and benign disease where there is concern regarding the functionality of the bladder. If they survive the first change and have a good prognosis, we will usually discuss conversion to a more long-term 29F Detour EAS. The latter stent requires a more invasive technique including an open cystostomy but has the advantage of potentially being a permanent diversion with a single procedure. We use it as a primary option in patients with a long life expectancy. Below, we describe our technique of inserting both types of stents.
