Stone Baskets and Forceps

Fig. 16.1

Examples of Dormia helical stone baskets: (a) Bagley (Boston Scientific, Natick, MA, USA). Courtesy of Boston Scientific. (b) Dormia basket with filiform tip

With the introduction of percutaneous stone removal in the late 1970s, the helical design of the Dormia basket proved unsuitable for use in the kidney, especially for the removal of calyceal stones. Problems with the use of these baskets included trauma to the collecting system from a rigid tip extending beyond the cage, particularly if the stone was in a calyx. Also, the long distance between the scope and the stone made engagement of the stone difficult.

The next generation of baskets was the Segura stainless steel four flat wire basket (Cook Urological, Bloomington, IN, USA), which was introduced in the early 1980s (Fig. 16.2). The basket could open widely in a relatively small space, which allowed capture of stones or stone fragments from the renal pelvis and calyces during PCNL (percutaneous nephrolithotomy). Although the Segura basket rapidly gained popularity, the rigid steel wires limited deflection of flexible nephroscopes and the protruding tip limited access to smaller calyces and tended to traumatize the papilla, causing bleeding.

Fig. 16.2

Example of Segura flat-wire basket

The introduction of the nitinol tipless basket marks the transition to the modern era of endourology [2]. The N-Circle was the first nitinol basket introduced (Cook Urological) (Fig. 16.3). Nitinol is a combination of nickel and titanium, and the flexibility of the material allowed full deflection of nephroscopes and later flexible ureteroscopes. The tipless design and the flexibility of nitinol prevented trauma to the papilla during removal of calyceal stones. The combination of nitinol and the tipless design results in almost immediate opening of the basket on deployment, allowing the capture of stones in small, shallow calyces, or indeed anywhere in the collecting system.

Fig. 16.3

NCircle (Cook Urological, 1.5 F): the earliest tipless nitinol basket. Permission for use granted by Cook Medical Incorporated, Bloomington, Indiana

Miniaturization of tipless nitinol baskets as small as 1.3 F in diameter allows improved irrigation when used with flexible ureteroscopes as small as 7.5 F. It was only with the introduction of nitinol baskets that it became possible to reliably access lower pole stones ureteroscopically, grasp and relocate them to the upper pole for fragmentation with the Holmium laser.

A number of companies have since modified the original Cook product, and at the latest count, there are 7 companies with 19 different nitinol baskets (Table 16.1). A variety of baskets with stainless steel construction and with tips remain commercially available (Table 16.2).

Table 16.1

Commercially available stone baskets for ureteroscopic use, constructed with nitinol

Configuration	Name	Company	Tip	Number of wires	Sizes (F)	Open diameters (mm)	Comments
Spherical	NCircle	Cook	Truly tipless	4	1.5, 2.2, 3.0, 4.5	10, 20	4.5 F is 20 mm
	NCircle MegaBasket	Cook	Truly tipless	4	2.2, 3.0	20
	NCircle Delta Wire	Cook	Truly tipless	4	2.4	10, 20	Triangular Delta wire provides largest possible wire mass for strength
	Zerotip	Boston Scientific	Truly tipless	4	1.9, 2.4, 3.0	12, 16	16 mm for 3.0 F
	Escape	Boston Scientific	Truly tipless	4	1.9	11–15	2 long wires convert 11 mm basket to 15 mm
	Optiflex	Boston Scientific	Truly tipless	4	1.3	6–11	Wheel on handle provides 360° cage rotation
	Dormia No-Tip	Porges	Truly tipless	4	2.2, 3.0	11, 15	2.2 F with twisted wires. 3.0 F with straight (“flat”) wires
	Halo	Sacred Heart	Truly tipless	4	1.5	12	Rotation control knob on handle
	Vantage	Sacred Heart	Truly tipless	4	2.4, 3.0	16
	Apex Nitinol Flat Wire	Sacred Heart	Soft	4	2.4	15	Flat wire design
	Dimension	Bard	Truly tipless	4	2.4, 3.0	10, 13, 16	Articulating basket
	Nitinol Stone Basket	Applied Medical	Truly tipless	4	3.0	12–14
Helical	Dormia NStone	Porges	Soft	4	2.5, 3.0, 4.0	12.5, 15	2.5 F: 12.5 mm. 3.0 and 4.0 F: 15 mm
	NCircle Helical	Cook	Truly tipless	4	3.0, 4.5	10, 20	4.5 F is 20 mm
	NForce	Cook	Soft or 5 or 7 cm filiform	3	2.2, 3.2	n/a	Soft tipped available in both sizes
Paired Wire	Surcatch NT	Gyrus ACMI	Truly tipless	6 (3 pairs)	1.9, 2.2, 3.0	16	Unique crossed paired wire design. Also available in stainless steel
Paired Wire	Paragon	Sacred Heart	Soft or 5 cm filiform	6	2.4, 3.0	10	3.0 F available with 5 cm tip
Other	NGage	Cook	Open (no tip)	3	1.7, 2.2	8, 11
Other	NCompass	Cook	Truly tipless	16	1.7, 2.4	10,15	Partially opened, resembles three (or four wires). Tight weave of wires when fully opened

n/a information not available

Applied Medical, Rancho Santa Margarita, CA, USA

Bard, Covington, GA, USA

Boston Scientific, Natick, MA, USA

Cook Urological, Bloomington, IN, USA

Gyrus ACMI, Southborough, MA, USA

Porges Urology, Division of Coloplast, Minneapolis, MN, USA

Sacred Heart Medical, Minnetonka, MN, USA

Table 16.2

Commercially available stone baskets for ureteroscopic use, constructed with stainless steel

Configuration	Name	Company	Tip	Number of wires	Sizes (F)	Open diameters (mm)	Comments
Spherical	Segura Hemisphere	Boston Scientific	Short or 5 cm filiform	4	2.4, 3.0, 4.5	16, 20	Round wires. Filiform tip only on 4.5 F with 20 mm basket
	Atlas	Cook	Short or 5 cm filiform	4	1.7–4.5	17
	Laser Flat-Wire	Cook	Short	4	2.5, 3.0	17	Hollow sheath for laser fiber; 150 μm fiber through 2.5 F and 273 μm fiber through 3.0 F
	Platinum Class Flat-Wire	Bard	Short	4	2.4	14
	Summit	Sacred Heart	Short or 5 cm filiform	4	3	20	Flat wires
	Dormia with extractable basket	Porges	Short	4	2.5, 3.0, 4.0	n/a	Also in helical configuration
	Dormia with olive tip	Porges	Short	4	2.5, 3.0, 4.0	n/a	Also in helical configuration
	SurLok Flat-Wire	Gyrus ACMI	Short or 5 cm filiform	4	2.4, 3.0. 4.5	16, 20	With locking mechanism. Round wires
Helical	Platinum Class Helical	Bard	Short or 5 cm filiform	n/a	3	14
	Expand 212	Bard	Short or 5 cm filiform	6	3	11	2-1-2-1 wire configuration. Nitinol drive wire
	Spira	Sacred Heart	Short or 5 cm filiform	4	3	n/a
	Rutner	Cook	Balloon tip	3	5.0, 7.0	14	4 cm balloon proximal to basket for ureteral dilation
	Captura	Cook	Short or 5 cm filiform	3–6	1.7–4.5	10
	Bagley	Boston Scientific	Short	3	1.9	10
	Dormia with extractable basket	Porges	Short	3, 4, 6	1.9, 2.5, 3.0, 3.5, 4.0, 5.5	n/a	Also in spherical configuration
	Dormia with olive tip	Porges	Short	4	2.5, 3.0, 3.5, 4.0, 5.5	n/a	Also in spherical configuration
	Pickstone	Porges	Short	4	2.9, 4.0	n/a	No extractable basket
	Surlok Helical	Gyrus ACMI	Short or 5 cm filiform	3, 4, 6	1.9, 3.0, 4.5	n/a	With locking mechanism
Paired Wire	Hercules	Sacred Heart	Short or 5 cm filiform	6	3.0	11	2 pairs and 2 single wires
	Surcatch	Gyrus ACMI	Short or 5 cm filiform	3 pairs	2.4, 3.0	11	Unique crossed paired wire design. Also available in nitinol
	Gemini	Boston Scientific	Short or 5 cm filiform	3–5 pairs	2.4, 3.0	11, 14	Grouped pairs arranged in helix
Other	Lithocatch	Boston Scientific	Soft	12	2.2	7	Designed to immobilize and sweep small fragments from ureter
Other	Leslie Parachute	Boston Scientific	Short or 5 cm filiform	∼ 8 (2 groups proximally)	3.1	11	2 proximal openings when open. When partially closed, multiple wires fan out to retain stone

n/a information not available

Some urologists have refrained from the use of stone baskets ureteroscopically for the fear of capturing a stone that could not be released. An unintentional benefit of the nitinol design is, however, the ability to flatten the loops of the open basket and release a stone; this was not possible with the flat wire baskets constructed of stainless steel. Since the 1990s, the use of nitinol baskets has increased dramatically, while the use of helical and Segura baskets has declined proportionally [3].

Stone Extraction Devices

Stone Baskets: General Discussion

Though there are many different stone basket types available for use today (Tables 16.1 and 16.2), there are elements common to all. At the distal end, there are 3–16 wires forming a basket cage (most commonly four), composed of either stainless steel or nitinol (nickel/titanium). There are a variety of basket cage configurations, including spherical, helical, paired wire, or tipless. The cage diameter typically ranges from 10 to 20 mm. There may be a tip protruding beyond the basket cage. The sheath on the basket shaft is typically composed of either polyimide or PTFE (polytetrafluoroethylene) and ranges from 1.5 to 5.5 F. Baskets are typically available in two lengths: shorter for use through a semirigid ureteroscope (65–90 cm) and longer for flexible ureteroscopes (115–120 cm). At the proximal end of the basket is a handle that opens or closes the basket; some have locking or basket articulating mechanisms (Fig. 16.4). When the basket is closed, the basket wires retract into the sheath, and the basket appears to shorten. Most baskets can be disassembled for removal of the ureteroscope through which it is placed in the event that a stone becomes impacted or “stuck” in the basket [1]. All stone baskets are for use in a single patient, but multiple stone extractions can be performed with a single device, so basket durability is of utmost importance.

Fig. 16.4

Picture of Cook NCircle basket, showing distal basket cage, sheath (115 cm), and removable handle

Key characteristics of a particular basket will affect its performance and its suitability for use in specific circumstances. These include

Basket material. The introduction of truly tipless nitinol baskets in the 1990s revolutionized the field of stone extraction devices. All previous baskets were composed of stainless steel which was strong, but these devices had several limitations (stiff tip, long excursion distances, etc.) related to the properties of the material and the basket designs of the time. Nitinol is flexible and resilient [2], and unlike stainless steel, it is kink resistant with excellent retention of shape in spite of repeated manipulations [4].

Number and configuration of the wires. Most baskets have at least three wires, and some even up to 16. Dormia helical baskets have classically been constructed of stainless steel and are most useful for the extraction of ureteric stones. Segura’s flat wire baskets were strong, with high levels of radial force generated, but were more traumatic than round wires. Most baskets today are made of round wires, with configurations that include spherical, helical, paired wire, or tipless (Fig. 16.5). Some stainless steel baskets are shown in Figs. 16.1 and 16.2.

Diameter of basket sheath. Flow through the ureteroscope is inversely proportional to the cube of the sheath diameter, so the smallest possible sheath will help to optimize the flow of irrigant to maintain visibility. Flow will be further impaired if another instrument, such as a laser fiber, is placed in the working channel. Smaller diameter baskets however are less kink-resistant and robust.

The presence or absence of a basket tip. The original Dormia and Segura stainless steel baskets all had tips protruding beyond the cage. The presence of a tip precluded the safe usage of the basket in the kidney, particularly for calyceal stones, due to the risk of collecting system or papillary trauma causing perforation or bleeding. Though most current nitinol baskets are tipless, baskets with 5–7 cm filiform tips remain available, intended specially for use in the ureter, particularly if it is tortuous. However, the use of filiform tips has not, to our knowledge, been supported by any in vivo or in vitro studies. Even with a tortuous ureter, it is preferable to straighten it by the placement of a guidewire prior to ureteral stone basketing. The use of a filiform tip without a guidewire is equivalent to blind basketing which is not recommended [5].

Though various manufacturers have described some baskets as “tipless,” there is still a definite tip remaining, with the potential to cause trauma to the collecting system. We have therefore classified baskets, through the remainder of this chapter and in Tables 16.1 and 16.2, into those that are “truly tipless,” “soft-tipped” (nitinol baskets with a definite tip), “short-tipped” (stainless steel baskets without a filiform tip that could be potentially traumatic if used incorrectly or in the kidney).

Degree of linear basket opening. Linear basket opening is the 1:1 correlation of handle movement to basket opening. The more linear the basket movement, the easier it is to capture small stones. Some baskets open exponentially: that is, with handle movement, the basket opens little initially until it suddenly springs open. When 13 basket types were compared, the Cook N-Circle basket was the only one to exhibit linear opening [6]. With the nitinol baskets, linearity of opening is related to basket shape: “walnut shaped” baskets (e.g., Zero-tip, Boston Scientific, Natick, MA, USA) tend to have exponential opening, where “tear shaped” baskets (e.g., N-Circle) have linear opening [7].

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