Stone Extraction

Introduction and Scientific Basis

Biliary stone disease is the most common reason for undertaking therapeutic endoscopic retrograde cholangiopancreatography (ERCP). In Western countries, choledocholithiasis is primarily related to passage of gallstones from the gallbladder into the common bile duct. The clinical presentation of choledocholithiasis varies from no symptoms to biliary colic, jaundice, cholangitis, and/or acute biliary pancreatitis. ERCP plays an important role in managing or preventing biliary complications of biliary stone disease.

After endoscopic sphincterotomy, the majority of stones less than 1 cm in diameter pass spontaneously. Nonetheless, it is current practice to attempt stone extraction and clearance of the bile duct to avoid potential subsequent stone impaction and adverse clinical consequences. Stones are most commonly extracted using a soft, compliant balloon catheter or wire (e.g., Dormia) basket. However, large stones, particularly those greater than 2 cm in diameter, can be difficult to remove and may require some form of stone fragmentation before removal. The most popular method of stone fragmentation is mechanical lithotripsy using large-diameter and robust baskets to break the stone. Other methods include intraductal electrohydraulic or laser lithotripsy and extracorporeal shock wave lithotripsy (ESWL). In rare cases where endoscopic stone extraction fails, surgery or chemical dissolution of the stone may be used. When endoscopic extraction fails, temporary biliary stenting provides decompression and is effective in controlling biliary sepsis. Subsequent additional elective endoscopic therapy can be undertaken to attempt stone clearance. Permanent plastic stenting can be used for biliary drainage in selected patients with large nonextractable stones to prevent cholangitis. It is worth noting that the advent of large-diameter papillary balloon dilation has not only increased the successful extraction of stones but also reduced the need for mechanical lithotripsy (see Chapter 18 ).

Diagnostic ERCP is usually performed using undiluted water-soluble contrast, and early filling fluoroscopic images should be carefully analyzed for stones, which are often seen as filling defects with a meniscus sign ( Fig. 19.1, A, B ). However, if the bile duct is dilated, diluted contrast should be used to avoid masking small stones by dense contrast in a dilated duct. In patients with suspected intrahepatic stones or stones located proximal to a stricture, an occlusion cholangiogram may also be necessary to visualize the stones ( Fig. 19.1, C ). This may carry a risk of precipitating or exacerbating cholangitis if excess contrast is injected into an obstructed system, causing a rise in intrabiliary pressure.

Although the majority of intraluminal filling defects in the bile duct are caused by stone disease, a filling defect is not pathognomonic for choledocholithiasis. Irregularly shaped or amorphous lesions can be related to other entities such as mucus, as in the case of intraductal papillary neoplasm of the bile duct (IPNB), blood clots, parasites, polypoid malignancies, or other etiologies. An appropriate differential diagnosis should be considered in the clinical context of the patient before attempting extraction of the filling defect.

To achieve successful stone extraction, it is of prime importance to assess the stone size relative to the size of the sphincterotomy and caliber of the distal common bile duct (i.e., the “exit passage”). The sphincterotomy should be of adequate size to allow passage of the stone. One method of gauging sphincterotomy size is to pull a fully bowed sphincterotome across the cut papilla. A generous sphincterotomy should allow easy passage of the bowed sphincterotome. An alternative method to gauge the ease of stone extraction is to pull an inflated stone extraction balloon (about the same size as the stone) through the distal bile duct and sphincterotomy. If the balloon passes easily, stone extraction will likely be simple. If the balloon becomes deformed as it passes through the distal bile duct or excess resistance is felt during balloon passage through the sphincterotomy, it is likely that stone extraction will be difficult and additional therapy—such as balloon dilation of the sphincterotomy and distal bile duct (see Chapter 18 )—may be required to facilitate stone extraction. In addition, appropriate accessories should be available to handle any foreseeable complications.

Dilation of a benign bile duct stricture may be necessary to remove stones that occur above a stricture and for intrahepatic stones. Dilation can be achieved using biliary dilation balloons, which are basically low-compliance balloons that can be inflated to a fixed diameter. These balloons are available in sizes ranging from 4 to 10 mm in diameter and can be placed over a guidewire across the stricture. Dilute contrast is used to inflate the balloon to a predetermined pressure as recommended by the manufacturer. The balloon has radiopaque markers that help with the positioning of the stricture at the midpoint of the balloon. The choice of balloon size should be based on the diameter of the normal portion of the bile duct and should not exceed this, in order to avoid unnecessary damage to the bile duct. The balloon is inflated to the recommended pressure, and the persistence or disappearance of the waist on the balloon is noted under fluoroscopy. This will determine the effectiveness of the dilation and ease of subsequent stone extraction through the stricture. If the stricture cannot be dilated adequately, stone fragmentation is necessary before attempting removal. Alternatively, the stricture can be treated (see Chapter 43 ) without attempting stone removal until it is adequately treated, as the indwelling stents are protected from stone-related clinical adverse events.

Balloon dilation or sphincteroplasty after an initial small sphincterotomy, or in specific cases without a sphincterotomy, has also been more frequently used to facilitate removal of a large stone while avoiding the risks of bleeding and perforation from a large sphincterotomy (see Chapter 18 ).

Biliary Stone Disease and Contraindications to ERCP (see Chapter 7 )

DescriptionS of Techniques

Removal of an Impacted Ampullary Stone

Attempts should be made to disimpact the stone proximally within the bile duct in order to achieve deep cannulation. However, it may be necessary to use a needle knife to cut directly onto the bulging papilla caused by the impacted stone to facilitate deep cannulation (i.e., precut sphincterotomy; see Chapter 15 ) with subsequent use of a standard sphincterotome and accessories for stone removal. It is possible sometimes to simply extend the cut using the needle knife, eventually delivering the impacted stone.

In cases where a stone is impacted right at the ampullary orifice, as can be seen in patients with acute biliary pancreatitis, a polypectomy snare can be positioned above the impacted stone and closed around the bulging papilla beyond the stone ( Fig. 19.2 ). The wire loop ensnares the bulging papilla and prevents the stone from migrating. With a gentle tug on the closed snare, the impacted stone can be expelled from the orifice. A subsequent sphincterotomy can be performed if residual stones are present in the bile duct. An indwelling biliary stent can be placed to ensure drainage if there is concern about stasis from a swollen papilla to prevent cholangitis.