Reviews of the Cook Medical NGage stone extractor | Which Medical Device

Device Features

A nitinol stone basket for endourology and interventional uroradiology. It does not project forward when opened.

Design/construction

The Nitinol ‘basket’ is not a true stone basket as it does not completely enclose the stone. I would describe it more as a multi loop snare. The 3 ‘snare’ loops are joined to one another so that a complete ring is formed around the stone as the ‘snare’ is closed.
The basket comes in 1.7 and 2.2F sizes which should allow good irrigation through the working scope channel. The open diameter is 8 and 11mm.

In Use

The ‘none closed’ nature of the basket gives a reasonable amount of radial force but still allows stones to be easily released. This is important as a large stone that becomes lodged in a normal basket then has to be broken with the laser. To do this the basket may have to be dismantled so that the scope can be removed then reinserted alongside the basket with the laser fibre through the working channel.
 
The disadvantage of this design is that stones cannot be grasped as firmly as needed on occasions and also larger stones cannot be grasped. Nevertheless we have found it excellent for small to medium sized intra renal calculi. Another good feature is the ability to torque the basket by rotating the handle which can help position it for some stones and also allows stones to be ‘stirred up’ by rotating the basket. Care needs to be taken if the basket is pushed onto a stone in a confined space as it sometimes partially turns inside out. It can be re aligned manually when removed.
 
We frequently use the basket during PCNL procedures through a flexible cystoscope to reach small stones in calyces that cannot be reached with the rigid scope from the puncture site. The grasp/ force of the basket is often sufficient to pull a stone down into the renal pelvis to allow it to be worked on through the rigid nephroscope.

Comparison with:
 

• Bard Dimension stone basket
  The Ngage is smaller allowing better irrigation through the working channel. The disadvantage is that it is less robust and torque is less forceful. The Ngage lacks the small amount of directional movement of the Dimension but is easier for the less experienced clinician to use.
   
• Boston Zero tip basket
  This used to be our standard intra renal basket. It is similar in size but cannot be torqued and needs to be pushed beyond/onto the stone to allow stone capture. Jammed stones mean the basket has to be dismantled to allow scope removal.
   
• Gooseneck Snare
  A great device from the armamentarium of interventional radiology. We occasionally use these single loop snares through an angled catheter to pull stones back into the renal pelvis from the upper pole. They are strong, torquable and the stone is easily released. They are available in a variety of sizes up to several cm. They are harder to use than the Ngage but stronger and can be easily seen on xray screening if direct vision is not possible. They are difficult for the non interventional radiologist to use and stones can be hard to grasp reliably.

Conclusion

This ‘basket’ has become one of our most used baskets for intrarenal stone extraction with the flexible ureteroscope. Most of the time it works, its torquable, allows good irrigation and stones can be released if needed.  However due to its small French size it easily degrades with repeated use.