Chapter 7: Endoscopic maneuvers of treatment of CBD stones

Endoscopic cannulation of the major papilla with imaging of the pancreatic duct and biliary tree or ERCP was first successfully accomplished with an end-viewing duodenoscope and reported in 1968. The subsequent development of side-viewing endoscopes with a catheter-deflecting elevator greatly facilitated the technique. Diagnostic studies were supplemented by the first endoscopic sphincterotomies in 1973. Techniques of biliary stone extraction, and biliary stent placement soon followed. These developments permitted less invasive diagnostic and therapeutic maneuvers in the pancreatic and CBD that were previously limited to open surgical and percutaneous techniques. Although these procedures are more technically demanding than most other gastrointestinal endoscopic techniques, they are now being widely applied and are the method of choice for many clinical problems involving the pancreatic duct and the hepatobiliary system (Sherman et al., 2007).

The role for diagnostic ERCP alone is diminishing as other less invasive/noninvasive imaging techniques EUS, MRCP become more widely used. ERCP is indicated in clinical settings in which there is significant suspicion of an obstructing, inflammatory, or neoplastic pancreaticobiliary lesion that if detected or ruled out, would alter clinical management. Although there are several indications of ERCP in suspected neoplastic lesions, both diagnostic and therapeutic, we will focus in this chapter on indications related to choledocholithiasis which can be summarized in the following:

Suspected Biliary Ductal Disorder:

·        Jaundice or cholestasis of suspected obstructive origin

·        Acute cholangitis

·        Gallstone pancreatitis

·        Clarification of biliary lesion seen on other imaging tests

·        Biliary fistula

Direct Endoscopic Therapy:

·        Sphincterotomy

·        Biliary drainage

·        Pancreatic drainage (Sherman et al., 2007)

 

           Stones less than 1 cm in diameter with normal terminal CBD/sphincter anatomy are considered routine because more than 85% can be managed by standard biliary endoscopic sphincterotomy and extraction (Yoo et al., 2010). 

           The following algorithm shows the proposed management of a routine (less than 1 cm) CBD stone management using ERCP as a primary line of treatment.

The only true absolute contraindications for ERCP procedure are both refusal of the patient to undergo endoscopy or an acute unstable cardiovascular or cardiopulmonary episode (Yakshe et al., 2000). Structural abnormalities of the esophagus, stomach or duodenum may be relative contraindications to ERCP. A large esophageal diverituclum, an unrecognized esophageal stricture, a large paraesophageal hiatus hernia, a gastric volvolus, a gastric outlet obstruction owing to a variety of reasons, a previous partial gastrectomy with Billroth type II anastomosis or a Roux-en-Y jejunojejunostomy may as well be relative contraindications to performing ERCP. The level of experience of the endoscopist is of outmost importance in the decision as to whether the procedure should be undertaken under these circumstances. Finally, a communicating pancreatic pseudocyst is also not an absolute contraindication to ERCP if drainage of the pseudocyst is to be endoscopically or surgically performed (Lopes et al., 2010).

               One of the challenges that face endoscopists performing ERCP is disturbed upper GIT anatomy due to previous operations, either Billroth II or Roux-en-Y. Roux-en-Y reconstruction is common in many surgical procedures such as Roux-en-Y gastric bypass (RYGB) for morbid obesity and pylorus-preserving pancreaticoduodenectomy for periampullary tumours in addition to other biliary tract surgeries. This represents a significant technical hinder for performing ERCP for cases of choledocholithiasis. (Table 5) summarizes the characteristics of the different approaches for ERCP in patients with Roux-en-Y anatomy (Lopes et al., 2010).

LAERCP: Laparoscopic assisted ERCP, RYGB: Roux-en-Y gastric bypass, bilioenteric (BE)/pancreatoenteric (PE) anastomosis.

    

          Approximately 10% to 15% of patients have bile duct stones that cannot be removed using standard biliary endoscopic sphincterotomy and balloon/basket extraction techniques. These stones generally are larger than 1.0 cm, impacted, located proximal to strictures, or associated with duodenal diverticula. Such factors make adequate sphincterotomy and extraction difficult. Ultimately, the stone must be (1) extracted from above (i.e., bile duct exploration), (2) made smaller (i.e., lithotripsy), or (3) have a larger passage way (i.e., large balloon dilation). All transpapillary intraductal approaches can also be performed via a percutaneous access with similar success rates but added complications of the transhepatic approach (McHenry et al., 2006).

Table (6): Risk factors for unsuccessful ERCP stone extraction (Colletti 2006).

Stone size >25 mm

Stone diameter greater than duct diameter

Intrahepatic stones

Multiple, tightly packed stones

Impacted stones

Common bile duct stricture

Duodenal diverituclum

Difficult anatomy (Billroth II, Roux-en-Y)

             

 

 

 

 

          Mechanical lithotripsy: One advantage of basket stone extraction is that the device can be used to mechanically crush stones if necessary. The handle of the basket device is connected to a specialized pistol grip that is used to forcefully close the basket over the stone until it fractures. The fragments are then removed with the basket or a balloon (Thomas et al., 2007).

               Electrohydraulic lithotripsy (EHL): Stones may be fractured using a shock wave applied directly to the surface. An electrohydraulic probe consists of two coaxially isolated electrodes at the tip of a flexible catheter capable of delivering electric sparks in short rapid pulses that generate pressure waves to fracture the stone. Because of the danger of applying this energy to the wall of the CBD, the procedure is most commonly done under direct endoscopic visualization using choledochoscopy (Dunkin 2012).

Laser lithotripsy: This device creates a shock wave via a flexible quartz fibre delivering light from a laser. The 504-nm pulsed-dye laser produces a pulse that is absorbed on the stone surface creating a plasma cloud that rapidly expands and contracts creating the shock wave that fractures the stone. As in EHL, the energy is applied under direct vision using choledochoscopy to avoid damage to the surrounding CBD wall (Cho et al., 2009).

Extracorporeal shock wave lithotripsy (ESWL): It generates a shock wave originating outside the body using piezoelectric, electrohydraulic, or electromagnetic systems. A liquid or tissue medium is required to prevent energy attenuation. Because ESWL is painful, general anaesthesia is required. Because most CBD stones are not radiopaque and are not visualized by fluoroscopy alone, a nasobiliary tube with contrast injection is required before ESWL. Complete stone clearance rates of 83% to 90% have been reported (Sackmann et al., 2001). A large prospective study reported that overall clearance rate with successful fragmentation was 84.5%, but a single session of ESWL cleared the stones in only 16% of 283 patients with large CBD stones (Tandan et al., 2009). Complications of ESWL have been minimal. A limitation is the considerable recurrence rate of bile duct stones after ESWL reported in 12.7% to 28% of patients on 1- to 3-year follow-up (Conigliaro et al., 2006).

           Decompression: On occasion, the CBD cannot be cleared of all stones or debris during one procedure. This may be because there is too much material to clear or that circumstances prevent performing a complex procedure, such as a critically ill patient with cholangitis or a pregnant woman in whom radiation exposure must be minimized. In these circumstances, decompression of the CBD provides effective drainage and allows for scheduling an elective completion procedure at a more optimal time. There are two methods of providing temporary decompression of the CBD (Dunkin 2012).

 

a)     Plastic stent: Small plastic tubes can be passed through the working channel of the endoscope and pushed into position in the CBD. These stents range in size from 7 to 11.5 French and come in various lengths. They also have either fixation flaps or a pigtail configuration to prevent migration. The stent is typically positioned with the proximal end in the common hepatic duct and the distal end in the duodenum. To improve drainage, multiple stents are sometimes placed next to each other. Plastic stents remain patent for about 2–3 months after which they must be exchanged or removed (Dunkin 2012).

 

b)    Nasobiliary drain (NBD): It is possible to decompress the biliary system by placing a drain via the nose down the oesophagus, across the stomach and duodenum, and into the CBD. The side holes in the NBD allow for bile to drain from the CBD into the duodenum, and the transnasal placement enables removal without repeat endoscopy. NBDs are used more commonly outside of the USA for temporary decompression of the biliary tree or instillation of solutions into it (Lee et al., 2007).

    The most common indication for ERCP during pregnancy is treatment of choledocholithiasis. Choledocholithiasis that causes cholangitis and pancreatitis during pregnancy increases the risk of morbidity and mortality for both the fetus and mother. ERCP, with modified techniques to reduce radiation exposure to the fetus, is safe during pregnancy.  Dosimetry should be routinely recorded. It may be possible to perform ERCP without fluoroscopy. Consultation with an obstetrician is recommended (Kahaleh et al., 2004).

    ERCP has been used in children for a variety of indications, usually related to recurrent acute pancreatitis, choledocholithiasis, or evaluation of suspected choledochal cysts. Several case series of ERCP in children have shown that, in experienced hands, the success and the safety is comparable with that in adults. Radiation exposure should be limited and additional pelvic shielding can be used to protect the reproductive organs. In most patients, adult duodenoscope can be used, but pediatric duodenoscope are available, although accessories for these devices are limited (Varadarajulu et al., 2004).

    ERCP is associated with a 7% complication rate and a 0.3% mortality rate. Risks associated with ERCP include those similar to other endoscopic procedure, such as those related to conscious sedation, drug reaction, and cardiopulmonary complication. There are also risks specifically related to the diagnostic and therapeutic aspects of ERCP which are discussed here in more detail (Marks et al., 2012).

           Multiple factors can predispose to the development of complications following ERCP. They are categorized into patient, procedure, and operator factors.

1)     Patient factors: Younger age (<60 years old) and Sphincter of Oddi dysfunction (SOD) are associated with higher rates of ERCP-induced pancreatitis. Some studies have shown as high as a 30% incidence of pancreatitis in young women with SOD undergoing an ES. Coagulopathy increases the risk of hemorrhage following sphincterotomy (Dunkin 2012).

 

2)     Procedure factors: Difficulty in cannulating the papilla is associated with a higher rate of complications following ERCP. Associated factors that suggest difficult cannulation include multiple pancreatic injections of contrast and performance of a precut sphincterotomy (Dunkin 2012).

 

3)     Operator factors: The experience of the endoscopist seems to be a factor in predicting complications from ERCP. One or fewer procedures per endoscopist per week, fewer than 40 endoscopic sphincterotomies per year, and fewer than 150 ERCPs per year are all associated with increased risk of complications (Dunkin 2012).

 

A. Pancreatitis

               Pancreatitis is the most common complication following ERCP. When searching the literature, it is clear that a set value for the definition of post procedural pancreatitis has not been consistently established. As many as 60% of patients may develop transient hyperamylasemia after ERCP. Clinical pancreatitis, defined as abdominal pain in combination with an amylase level above three times the upper limit of normal, occurs in approximately 5% of patients (Andriulli et al., 2007).

          Most cases of post-ERCP pancreatitis (>90%) are mild to moderate and self-limited. Unfortunately, there have been rare cases of fatal necrotizing post-ERCP pancreatitis reported. Post-ERCP pancreatitis has an increased incidence in therapeutic ERCP when compared to diagnostic ERCP. It is more common in younger patients, females, and those with previous or recurrent pancreatitis. Patients undergoing ERCP for suspected SOD also have an increased risk for post-ERCP pancreatitis (Aronson et al., 2002).

B. Hemorrhage

           Hemorrhage following ERCP is related to many factors, including technical approach and preoperative optimization. Patients with obstructive jaundice may have impaired vitamin K absorption. This is particularly important for patients undergoing therapeutic ERCP as the patient may require an endoscopic biliary or pancreatic sphincterotomy.  If the ERCP can be delayed, treatment with vitamin K to correct the Prothrombin time PT should be undertaken. For those who require an urgent intervention, fresh frozen plasma must be administered (Aronson et al., 2002).

             Most cases of bleeding during ERCP are mild and self-limited, presuming that the patient has a normal coagulation profile. However, endoscopic sphincterotomy is a predisposing factor to clinically significant bleeding, which is reported in 2% of cases (Andriulli et al., 2007).

 C. Cholangitis

             The overall incidence of cholangitis following ERCP is low, around 1% in many large studies, but is one of the most potentially morbid complications. In patients who do not have evidence of biliary obstruction, cholangitis following ERCP is exceedingly rare (Andriulli et al., 2007).

D. Perforation

           All endoscopic procedures carry an associated risk for perforation, often related to traumatic passage or manipulation of the endoscope/endoscopic instruments. ERCP is unique in that in addition to the standard perforation risks there are additional risks for retroperitoneal duodenal or biliary perforation. When combined, the risk for any type of perforation is rare; occurring in less than 0.6% of cases, but each requires prompt diagnosis and treatment to avoid associated morbidity (Aronson et al., 2002). Retroperitoneal duodenal perforations are the most common location and can be misdiagnosed as pancreatitis on presentation. These perforations are often a result of an extensive endoscopic sphincterotomy that continues beyond the portion of the bile duct contained by the duodenum (Andriulli et al., 2007)

 

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