590 CHAPTER 16 Urological surgery and equipment

Guide wires

Guide wires are an essential tool for endourological procedures.

Uses

They are used as a track over which catheters or instruments can be passed into the ureter, collecting system of the kidney (retrograde or antegrade), or the bladder.

Types

Many different types of guide wire are available. They are classified according to their size, tip design, rigidity, and surface coating. These specific properties determine their use. All are radio-opaque so X-ray screening can be used to determine their position.

They come prepackaged in a coiled sheath to allow ease of handling and storage (Fig. 16.7).

Size

Size refers to diameter measured in inches (length is usually around 150 cm). The most common sizes are 0.035 inches and 0.038 inches. They are also available in 0.032 inches.

Tip design

The shape of the tip is either straight or angle (Fig. 16.8). A straight tip is usually adequate for most uses. Occasionally, an angle tip is useful for negotiating an impacted stone or for placing the guide wire in a specific position.

Similarly, a J-shaped tip can negotiate an impacted stone—the curved leading edge of this guide wire type can sometimes suddenly flick past the stone (in this situation, a straight guide wire can inadvertently perforate the ureter, thereby creating a false passage).

Surface coating

Most standard guide wires are coated with polytetrafluoroethylene (PTFE), which has a low coefficient of friction, thus allowing easy passage of the guide wire through the ureter and of instruments over them.

Some guide wires are coated with a polymer that when wet is very slippery (hydrophilic coating). In some cases, the entire length of the guide wire is so coated (e.g., Terumo Glidewire) and in others, just the tip (e.g., Sensor guide wire). The virtually friction-free surface of Glidewires makes them liable to slip out of the ureter, and they therefore make unreliable safety wires (they can be exchanged for a wire with greater friction via a ureteric catheter).

If allowed to become dry, these wires have a high coefficient of friction, which makes them difficult to manipulate.

Tip rigidity

The tip of all guide wires, over at least 3 cm, is soft and therefore flexible. This reduces—though does not completely remove—the risk of ureteric perforation.

592 CHAPTER 16 Urological surgery and equipment

Irrigating fluids and techniques of bladder washout

Glycine is used for endoscopic surgery requiring application of diathermy. Normal saline is used for the following:

•Irrigation of bladder following TURP, TURBT

•Irrigation during ureteroscopy, PCNL

Blocked catheter post -TURP and clot retention

To avoid catheter blockage following TURP, keep the catheter bag empty; ensure a sufficient supply of irrigant solution.

The bladder will be painfully distended. Irrigant flow will have stopped. A small clot may have blocked the catheter or a chip of prostate may have stuck in the eye of the catheter. Attach a bladder syringe to the end of the catheter and pull back (Fig. 16.9). This may suck out the clot or chip of prostate and flow may restart.

If it does not, draw some irrigant up into the syringe until it is about halffull and forcefully inject this fluid into the bladder. This may dislodge (and fragment) a clot that has stuck to the eye of the catheter.

If the problem persists, change the catheter. You may see the obstructing chip of prostate on the end of the catheter as it is withdrawn.

Blocked catheter post -TURBT

Use the same technique as for post-TURP catheter blockage, but avoid vigorous pressure on the syringe—the wall of the bladder will have been weakened at the site of tumor resection and it is possible to perforate the bladder, particularly in elderly women, who have thin bladder walls.

Blocked catheters following bladder augmentation or neobladder

The suture line of the augmented bladder is weak, and overvigorous bladder washouts can rupture the bladder.

IRRIGATING FLUIDS AND TECHNIQUES OF BLADDER WASHOUT 593

Figure 16.9 A bladder syringe—the tip is designed to fit onto a catheter.