Stone retrieval baskets are a common accessory used during ERCP. For most physicians new to ERCP, stone retrieval baskets may be limited to just "tools for picking up stones," insufficient for handling complex ERCP situations. Today, I will summarize and learn about ERCP stone retrieval baskets based on relevant information I've reviewed.
General Classification
Stone retrieval baskets are categorized as guidewire-guided baskets, non-guidewire-guided baskets, and integrated baskets. Integrated baskets include standard baskets such as Micro-Tech and Rapid Exchange (RX) baskets such as Boston Scientific. Because integrated baskets and Rapid Exchange baskets are more expensive than standard baskets, some institutions and surgeons may avoid using them due to cost considerations. However, regardless of the direct cost reduction, most surgeons prefer to use guidewire-guided baskets for lithotripsy, especially for larger bile duct stones.
Basket shapes can be categorized as "hexagonal," "diamond," and "spiral." These include diamond, domia, and spiral shapes, with domia baskets being the most commonly used. Each basket has its own advantages and disadvantages, and the choice should be flexible based on actual circumstances and personal preferences.
Because both diamond and domia baskets have a flexible "expanded front and narrowed back" structure, they facilitate stone removal. If a large stone becomes stuck and cannot be removed, the basket can be released smoothly, avoiding embarrassing accidents.
Ordinary "Diamond" Basket
Regular "hexagonal" baskets are relatively rare, or are used only in lithotripsy baskets. Due to the larger space within the diamond basket, smaller stones can easily escape. Spiral baskets are easy to insert but difficult to remove. Using a spiral basket requires a thorough understanding of the stone and anticipating the operation to minimize stone jams.
Spiral Basket
During the removal of larger stones, a quick-change basket with integrated pulverization and crushing functions is used, shortening surgical time and increasing the success rate of pulverization. Furthermore, if the basket is used for imaging, a pre-flushing and contrast agent removal procedure can be performed before the basket enters the bile duct.
II. Production Process
The stone retrieval basket's main structure consists of a basket core, an outer sheath, and a handle. The basket core is composed of basket wire (titanium-nickel alloy) and draw wire (304 medical stainless steel). The basket wire is a braided alloy structure, similar to the braid of a snare, which helps capture the target, prevents slippage, and maintains high tension, making it less susceptible to breakage. The draw wire is a specialized medical wire with high tensile strength and good toughness, so it will not be discussed in detail here.
This section focuses on the welds between the draw wire and the basket wire, and between the basket wire and the metal head. The welds between the draw wire and the basket wire are particularly critical. This design places extremely high demands on the welding process. Poor-quality baskets may not only fail to fragment the stones, but they can also cause the welds between the pull wire and the mesh basket wire to break during lithotripsy after removal, leaving the basket and stone trapped in the bile duct. This can make subsequent stone removal difficult (usually requiring a second basket) and may even require surgery.
Many standard baskets have poor welding between the guide wire and the metal tip, which can easily lead to basket breakage. However, Boston Scientific baskets go the extra mile and incorporate a safety mechanism. This means that if high-pressure lithotripsy still fails to fragment the stone, tightening the basket protects the metal tip at the front, ensuring the integrity of the basket guide wire and the pull wire, thus preventing the basket and stone from remaining in the bile duct.
I won't go into detail about the outer cannula and handle. Stone crushers from different manufacturers vary, and I'll explore this in more detail later.
How to Use: Removing impacted stones can be a complex process. This may be due to the surgeon's underestimation of the patient's condition and appendages, or it may be due to the characteristics of the bile duct stones themselves. In any case, we must first understand how to avoid impaction, and secondly, what to do if impaction occurs.
To avoid basket impaction, a cylindrical balloon should be used to dilate the papillary opening before stone removal. Other methods for removing impacted baskets include using a second basket (basket-to-basket) and surgical retrieval. A recent article also reported that APC can be used to burn off half (two or three) of the guidewires, thereby releasing the impacted basket.
IV. Treatment of Stone Basket Impaction
Basket use primarily involves two aspects: basket selection and basket removal. Basket selection depends primarily on the basket's shape and diameter, as well as whether emergency lithotripsy is used or available (generally available in endoscopy centers).
Currently, the "diamond-shaped" basket, also known as the Dormia basket, is commonly used. The ERCP guidelines specifically mention this basket in the section on common bile duct stone removal. It has a high stone removal success rate and is easy to remove, making it the preferred choice for most stone removal procedures. Basket diameter should be selected based on stone size. I can't elaborate on choosing a basket brand; please choose based on your personal preference.
Stone retrieval technique: Place the basket over the stone and perform stone removal testing under contrast imaging. Of course, before stone removal, perform either EST or EPBD, depending on the stone size. When the bile duct is damaged or narrowed, there may not be enough space to open the basket, so stone removal should be tailored to the specific situation. It is even possible to move the stone to a more spacious bile duct for removal. For bile duct stones in the hilar region, be aware that during basket removal or testing, the stone may be pushed into the liver and cannot be retrieved.
Stone retrieval with a basket requires two conditions: first, sufficient space above or beside the stone to open the basket; second, avoid removing large stones, which may be difficult to retrieve even with the basket fully opened. We have also encountered cases where stones as large as 3 cm were removed after endoscopic lithotripsy. In these cases, lithotripsy surgery is necessary. However, this procedure carries significant risks and requires the expertise of an experienced surgeon.
