Overview

Although the era of intervention for choledocholithiasis can be traced to over a century ago, with the first successful common bile duct (CBD) exploration by Thornton in 1889 and with the introduction of catheter-based biliary decompression by Courvoisier and Kehr, significant advances and refinements did not occur until recent decades. For many years, open cholecystectomy and exploration of the CBD remained the standard treatment for patients with choledocholithiasis, and it was a procedure carried out on a regular basis by most general surgeons. During that era, the morbidity and mortality rates of CBD exploration were very low, the percentage of retained stones was only 1% to 3%, and in long-term follow-up, revisional surgery was necessary in only about 10% of the patients (Gonzalez et al, 1997; Hammarström et al, 1995; Neoptolemos et al, 1987; Targarona et al, 1996).

The past 3 decades, however, have seen major changes in the management of choledocholithiasis, prompted by the introduction of high-quality noninvasive imaging, the more widespread availability of percutaneous and endoscopic approaches to duct clearance (see Chapters 27 and 28), and the introduction of minimally invasive surgical approaches in the performance of choleycstectomy and CBD exploration (see Chapter 34). Although the overwhelming majority of cholecystectomies are now performed laparoscopically, laparoscopic exploration of the common bile duct (LCBDE) is infrequently performed, given the advanced skills typically required and the availability of endoscopic retrograde cholangiopancreatography (ERCP; see Chapter 18). In a recent survey of general surgeons practicing in a rural area of the United States, the preferred approach to choledocholithiasis was ERCP (75%), followed by laparoscopic (21%) and open (4%) exploration. Time constraints and lack of equipment were the main factors preventing the application of the laparoscopic technique for treating choledocholithiasis (Bingener & Schwesinger, 2006).

Despite these considerations, there remain indications for operative choledochotomy and, more specifically, for open exploration. This chapter presents a review of the clinical features of choledocholithiasis with an emphasis on the technical aspects of open CBD exploration.

Origin of Choledocholithiasis

Most CBD stones are secondary in nature, having migrated from the gallbladder. This is in contrast to primary CBD stones that originate within the CBD. The existence of such primary stones is suggested by their occurrence in patients with congenital absence of the gallbladder and in those whose CBD had been previously cleared at the time of prior cholecystectomy. The practice of routine cholangiography during the era of open cholecystectomy was common and demonstrated an incidence of choledocholithiasis approaching 10% in patients without clinically evident common duct involvement (McSherry & Glenn, 1980; Hampson et al, 1981; Doyle et al, 1982; Lygidakis, 1983; Coelho et al, 1984; Ganey et al, 1986; DenBesten & Berci, 1986; Girard, 2000). Some 10% to 15% of gallstone patients concomitantly suffer from bile duct stones. In the United States and other Western countries, CBD stones are predominantly secondary, although primary stones are more common in Asia. This is associated with the high incidence of intrahepatic bile duct stones seen primarily in Southeast Asian countries, Taiwan, Hong Kong, and Singapore (Kim et al, 1995; see Chapter 39). The relative prevalence of intrahepatic bile duct stones in all gallstone cases in Taiwan is extremely high (>50%), and coexisting intrahepatic and extrahepatic bile duct stones are found in approximately 70% of these. Furthermore, the gallbladder stones are primarily cholesterol or black-pigment stones, whereas most bile duct stones are brown-pigment (calcium bilirubin stones).

Clinical Features

The natural history of CBD stones is unpredictable, with many small stones passing spontaneously. In the era of open cholecystectomy, a healthy debate surrounded the need for routine intraoperative cholangiography in patients without clinical signs of choledocholithiasis. Detractors noted that although 10% to 15% of patients had cholangiographic findings of CBD stones when routine cholangiography was used, a much lower percentage of patients developed clinical sequelae of CBD stones in series that utilized a more selective approach to cholangiography.

More recent series of laparoscopic cholecystectomy with a selective approach toward cholangiography appear to confirm this same experience (Fogli et al, 2009). In one of the more notable recent experiences, Collins and colleagues (2004) identified filling defects consistent with stones in 4.6% of patients. In these patients, access was maintained for the performance of postoperative cholangiograms. At 48 hours, 26% of patients had a normal cholangiogram, and an additional 26% had evidence for passage of the stones by 6 weeks. Twenty-two patients (2.2% of total population) had persistent CBD stones at 6 weeks after laparoscopic cholecystectomy and underwent ERCP for retrieval (Collins et al, 2004).

Symptomatic presentations include biliary colic, jaundice, cholangitis, pancreatitis, or combinations of these. Infection in the setting of CBD obstruction gives rise to the classic triad of fever with chills, jaundice, and pain; in some patients this can be associated with clinical signs of sepsis (see Chapter 43). In the absence of infection, jaundice may occur in an often fluctuating manner, as the stone intermittingly obstructs passage of bile. Over long periods, this process can lead to secondary biliary cirrhosis. After biliary colic, pancreatitis is the second most frequent symptomatic presentation of CBD stones (see Chapter 53). Depending on the timing of cholangiography, CBD stones can be identified in up to 50% of patients. Patients who have symptomatic bile duct stones are at risk of experiencing further symptoms or complications if left untreated. More than one half of patients who had retained bile duct stones experienced recurrent symptoms during a follow-up period of 6 months to 13 years (Johnson & Hosking, 1987), and 25% developed serious complications (Caddy & Tham, 2006). Given the potentially serious nature of CBD stones, it is critical that an approach be adopted to identify patients with CBD stones and ensure their clearance.

Preoperative Diagnosis

The identification of patients with choledocholithiais in the absence of clinical signs requires a careful history and physical examination in conjunction with attention to routine blood work and abdominal ultrasound. Clinical, ultrasonographic, and serum chemistry data are sensitive in 96% to 98% and specific in 40% to 75% for identification of patients with choledocholithiasis (Alponat et al, 1997; Koo & Traverso, 1996; Trondsen et al, 1998). Liu and colleagues (2001) triaged patients before laparoscopic cholecystectomy using guidelines incorporating patient information obtained from clinical evaluation, serum chemistry analysis, and abdominal US and assigned them into four groups based on the level of suspicion for choledocholithiasis (group 1, extremely high; group 2, high; group 3, moderate; group 4, low). The occurrence of choledocholithiasis was 92.6%, 32.4%, 3.8%, and 0.9% for groups 1, 2, 3, and 4, respectively. Patient triage resulted in the identification of CBD stones during preoperative ERCP in 92.3% of the patients who were subsequently referred for endoscopic clearance. Many other groups have also demonstrated the value of liver function tests (LFTs) in predicting the presence of CBD stones (Peng et al, 2005; Sgourakis et al, 2005). Although the trends of bilirubin and alkaline phosphatase are more typically used, a raised gamma-glutamyltransferase level has been suggested to be the most sensitive and specific indicator of CBD stones. A value greater than 90 U/L has been proposed to indicate a high risk of choledocholithiasis, with sensitivity and specificity of 86% and 74.5%, respectively (Peng et al, 2005).

In patients identified to be at risk by clinical history and/or abnormalities in serum chemistries, if imaging and therapy are necessary, an efficient and thoughtful approach is required. Transabdominal ultrasound (TUS) is the most commonly used initial diagnostic tool for suspected biliary stones (see Chapter 13). It has the advantage of being noninvasive, widely available, and inexpensive; however, US is highly operator dependent. TUS has low sensitivity, 25% to 60%, for detection of bile duct stones, but it has a very high specificity, 95% to 100% (Sugiyama & Atomi, 1997; Amouyal et al, 1994). Indirect evidence, such as the presence of gallstones or biliary ductal dilation with a CBD diameter greater than 6 mm in the appropriate clinical setting, is predictive of bile duct stones.

Computed tomography (CT) scanning has a similarly low sensitivity in the detection of bile duct stones and is used primarily to document biliary dilation or to exclude other causes of biliary obstruction (e.g., a mass lesion; see Chapter 16). The role of helical CT cholangiography is still in evolution, particularly in the United States. Intravenously administered contrast agents combined with high-resolution helical scans and three-dimensional reconstructions can be very useful in diagnosing choledocholithiasis (Cabada Giadàs et al, 2002; Maniatis et al, 2003). The sensitivity of this technique can be as high as 97%, and the specificity is 85% to 96% (Polkowski et al, 1999; Cabada Giadas et al, 2002; Maniatis et al, 2003; Gibson et al, 2005; Kim et al, 2007). Although this accuracy is comparable to magnetic resonance cholangiopancreatography (MRCP), helical CT cholangiography is limited by 1) possible allergic reactions to the contrast agents, as high as 15% in one series using intravenous iotroxate (Gibson et al, 2005); 2) suboptimal ductal contrast opacification in the presence of significant jaundice, evidenced by bilirubin more than two or three times the upper limits of normal (Polkowski et al, 1999; Soto et al, 1999); and 3) limited visualization of intrahepatic duct branches, particularly when using oral contrast agents (Gibson et al, 2005; Chopra et al, 2000).

Since its introduction in 1991 (Wallner et al, 1991), MRCP has emerged as an accurate, noninvasive diagnostic modality for investigating the biliary and pancreatic ducts (Hallal et al, 2005) and has been recommended in some circles as the preoperative procedure of choice for the detection of CBD stones (Hallal et al, 2005; Taylor et al, 2002; Topal et al, 2003; see Chapter 17). MRCP provides excellent anatomic detail of the biliary tract and has a sensitivity of 81% to 100% and a specificity of 92% to 100% in detecting choledocholithiasis (Hallal et al, 2005). The accuracy of MRCP in diagnosing CBD stones is comparable with that of ERCP (see Chapter 18) and intraoperative cholangiogram (Hallal et al, 2005; Vargghese et al, 2000; see Chapter 21). It thus avoids the need for an invasive procedure in about 50% of patients (Demartines et al, 2000), allowing selective use of ERCP or surgical CBD exploration in those patients who require a therapeutic intervention. These results have led some practitioners to consider MRCP the new gold standard for biliary imaging (Hallal et al, 2005; Shanmugam et al, 2005), although MRCP may miss stones smaller than 5 mm in diameter. It can also underestimate the number of stones detected (Vargghese et al, 2000). MRCP is an expensive option that requires significant expertise for interpretation, and it may not always be readily available.

For years, the gold standard for preoperative visualization of the bile duct has been ERCP (see Chapter 18); however, the nonselective use of ERCP in all patients with suspected choledocholithiasis detects CBD stones in less than 50% (Behrns et al, 2008; Petrov et al, 2008) and results in over half of patients undergoing an unnecessary procedure, exposed to its associated morbidity and mortality. The first publications on the usefulness of the alternative, noninvasive modality, endoscopic ultrasonography (EUS), in diagnosing CBD stones appeared around 1990 (Amouyal et al, 1989; Edmundowicz et al, 1992; see Chapter 14). Since then, more than 25 prospective studies, incorporating more than 2500 patients with suspected choledocholithiasis, have shown excellent accuracy with EUS, as well as safety.

The overall diagnostic performance of EUS has been evaluated in two recent metanalyses (Garrow et al, 2007; Tse et al, 2008); the pooled sensitivity and specificity of EUS were 89% to 94% and 94% to 95%, respectively. A review of all randomized controlled trials of EUS-guided ERCP versus ERCP alone in patients with suspected choledocholithiasis demonstrated that by performing EUS first, ERCP may be safely avoided in two thirds of patients, and the use of EUS significantly reduced the risk of overall complications and post-ERCP acute pancreatitis (Petrov & Savides, 2009). The data suggest that the ERCP should be reserved solely for patients with a high probability of CBD stones.

Before the advent of laparoscopy, preoperative clearance of CBD stones with ERCP before open exploration was uncommon. Several well-performed studies did not demonstrate any improvement in morbidity or mortality with preoperative endoscopic sphincterotomy (Heinerman et al, 1989; Neoptolemos et al, 1988; Stain et al, 1991). One study showed an increase in morbidity when preoperative ERCP with sphincterotomy was added to open cholecystectomy compared with cholecystectomy and open CBD exploration (Stain et al, 1991). A Cochrane systematic review by Martin and colleagues (2006) showed that open surgery results in a lower primary treatment failure, fewer additional procedures, fewer average number of procedures required per patient, and less mortality. Largely based on these studies, preoperative ERCP with sphincterotomy was uncommon in the era of open cholecystectomy, and it did not become more widespread until laparoscopic approaches to cholecystectomy appeared.

When laparoscopic cholecystectomy was introduced, preoperative ERCP was frequently used for patients suspected of having choledocholithiasis, as evidenced by jaundice, elevated liver function tests, a history of pancreatitis, and a dilated biliary system. Even with these criteria, however, it is difficult to predict which patients will have choledocholithiasis, and a negative ERCP was performed in 40% to 70% of patients, because most of these abnormalities were caused by transient biliary obstruction secondary to stones that subsequently passed into the duodenum (Stain et al, 1991; Ponsky, 1992; Delorio et al, 1995; Cotton, 1993; Cuschieri et al, 1996).

Two prospective randomized controlled trials have compared preoperative ERCP with sphincterotomy followed by laparoscopic cholecystectomy during the same hospital admission with single-stage laparoscopic management (Cuschieri et al, 1999; Sgourakis et al, 2005). The results demonstrate equivalent success rates of duct clearance and patient morbidity for the two management options, but a significantly shorter hospital stay was reported with the single-stage laparoscopic treatment. Cuschieri and colleagues (1999) concluded that in fit patients (ASA I and II), single-stage laparoscopic treatment is the better option, and preoperative endoscopic sphincterotomy (ES) should be confined to poor-risk patients, such as those with cholangitis or severe pancreatitis.

Performing ERCP has clinical and financial costs that must be weighed against the likelihood of successful extraction of stones that otherwise would result in significant disease manifestation. Complications that include postprocedural pancreatitis, bleeding, infections, and perforations are not uncommon. ERCP has an overall complication rate of 10% and a mortality rate less than 0.5% (Ponsky, 1992; Delorio et al, 1995; Cotton, 1993; Davis et al, 1997). A recent systematic analysis of prospective studies has shown that complications continue to occur at a relatively consistent rate and that the majority of events are of mild to moderate severity (Andriulli et al, 2007).

Certain clinical situations mandate preoperative ERCP. Preoperative endoscopic drainage should be used in acute cholangitis for decompression and amelioration of sepsis (Cuschieri et al, 1999; Leung, 2003) and in patients with severe gallstone pancreatitis and evidence of persistent choledocholithiasis. Patients with other major comorbidities or limited life expectancy represent another indication for ERCP with endoscopic sphincterotomy (ES) and decompression (Cuschieri et al, 1999), often as the definitive management without cholecystectomy.

Common Bile Duct Exploration at Cholecystectomy

In the early 1970s, ES was introduced as a treatment modality for CBD stones. During the following decades, it gained wide acceptance as a less invasive, highly effective alternative for the treatment of biliary obstruction as a result of gallstones (see Chapters 18 and 27). However, in patients with residual stones in the gallbladder, subsequent cholecystectomy was considered necessary. In a prospective randomized trial, it was demonstrated that ES before open cholecystectomy did not lead to earlier recovery or less postoperative morbidity compared with primary open cholecystectomy combined with CBD exploration. In a prospective randomized trial published in 1995 by Hammarström and colleagues, an expectant policy after ES was compared with open cholecystectomy combined with CBD exploration. It appeared that 20% of the patients after ES alone needed cholecystectomy during follow-up.

Similar results were reported in 1996 by Targarona and colleagues. In this prospective randomized trial of high-risk patients, the policy of ES and subsequent open cholecystectomy was compared to ES alone. In their experience, patients who underwent elective open cholecystectomy had significantly fewer recurrent biliary symptoms (6% vs. 21%) and needed fewer readmissions (4% vs. 23%) than patients who did not undergo surgery after ES. (Targarona et al, 1996). Given the recognition that cholecystectomy is necessary in most patients with CBD stones, even in the presence of a papillotomy, the appropriate timing and method of CBD clearance must be considered.

In less developed health care environments, where endoscopic or percutaneous approaches to biliary decompression and stone clearance are limited, open cholecystectomy with bile duct exploration is indicated in patients with a strong clinical suspicion for common duct stones, such as those with abnormal LFTs or cholangitis, as well as when palpable stones are present in the CBD, or when stones are visualized on an intraoperative cholangiogram.

In more developed health care settings with access to endoscopic, radiologic, or laparoscopic expertise, there will still be some patients in whom an open approach to CBD exploration is required. These include 1) patients with large or impacted CBD stones, in whom biliary enteric drainage is indicated; 2) those with anatomic considerations that preclude endoscopic treatment, such as prior gastric resection, duodenal diverticulae, and so on; and 3) patients who require an open approach for cholecystectomy, including those with Mirizzi syndrome, biliary-enteric fistula, a high index of suspicion for cancer, and those with CBD stones demonstrated by palpation or cholangiogram.

Postcholecystectomy Choledocholithiasis

Incidence

Although most initial operations for gallstone disease with or without demonstrated choledocholithiasis are curative, a few patients are found later to have additional stones in the CBD. Approximately 1% to 2% of all patients who undergo cholecystectomy have stones left in the CBD that require further intervention (Roslyn, 1993). Although retained or overlooked calculi after open cholecystectomy without CBD exploration are rare (Bergdahl & Holmlund, 1976), their incidence after open cholecystectomy with concomitant CBD exploration has been reported to be less than 5% (Dayton et al, 1984; Kappes et al, 1982; Roslyn, 1993), with a higher frequency after positive than after negative CBD exploration. After a second operation on the biliary tract, a recurrence rate of approximately 20% has been reported (Saharia et al, 1977; Way, 1973), with even higher rates after subsequent reoperation (Allen et al, 1981).

Treatment

The choice of management is determined by the clinical presentation, condition of the patient, availability of equipment, availability of clinical expertise, and presence or absence of a T-tube. Currently, operative management of retained and recurrent CBD stones is resorted to only if nonoperative procedures have failed.

Retained Stones in the Presence of a T-Tube

With the advent of laparoscopic biliary surgery, the use of the T-tube has become less common, eliminating methods for accessing the biliary tree postoperatively without an invasive procedure. If a patient with a retained CBD stone is in the immediate postoperative period and still has a T-tube in place, the management options are observation, mechanical extraction, or ES.

In the absence of biliary obstruction or infection, no treatment is necessary for 4 to 6 weeks. During this time, 10% to 25% of retained stones found on postoperative cholangiography can be expected to pass spontaneously into the duodenum, and no further treatment is required. If after 4 to 6 weeks the stone persists, the choice of treatment is between a radiologic approach through the T-tube tract (see Chapter 28) or endoscopic retrograde sphincterotomy (see Chapter 27). Because of its high success rate and low morbidity and mortality, nonoperative mechanical extraction through the T-tube tract is an attractive treatment choice. A success rate of 95% has been reported with a morbidity rate of only 4% (Mazzariello, 1978). Burhenne (1980) reported no deaths in 661 patients. When complications do occur, they can be treated medically in most instances, and only 0.2% of cases have required surgery (Mazzariello, 1978).

ES also has been shown to be effective in the management of retained stones in the early postoperative period after exploration of the CBD with a T-tube still in place (Hammarström et al, 1996; O’Doherty et al, 1986). Although ES has the considerable advantage that it can be carried out as soon as retained stones are discovered, treatment may be unnecessary in some patients, because stones may pass spontaneously. The results of mechanical stone extraction through the T-tube tract are better than any reported for ES (Lambert et al, 1988), which may be best used when the patient is clinically unstable, the T-tube is inappropriate in size and position, or mechanical extraction through the T-tube has failed. If these techniques fail, operative management can be resorted to with the expectation of a high success rate and rates for morbidity and mortality comparable to those for endoscopic retrograde sphincterotomy (Cameron, 1989; Girard & Legros, 1981).

Retained or Recurrent Stones in the Absence of a T-Tube

For a patient without a T-tube in place, ES is the procedure of choice and should be attempted first (Cameron, 1989; Sivak, 1989). Most reports of ES indicate a success rate in achieving overall clearance of stones from the CBD of more than 85% (Cotton, 1984; Lambert et al, 1991). Although early complication rates for ES are 5% to 10%, with emergency surgery being required in 1% to 2% of cases, most complications can be managed conservatively (Cotton, 1984; Escourrou et al, 1984). Hemorrhage, pancreatitis, cholangitis, and perforation are the most frequent complications, and mortality usually is reported at 0.5% to 2% (Lambert et al, 1991; Sivak, 1989). Long-term complication rates, mainly from stenosis or new stones or both, are low (<10%), and most complications can be managed endoscopically (Cotton, 1984; Escourrou et al, 1984; Hammarström et al, 1996; Sivak, 1989).

If for any reason ES is contraindicated, or if it fails, operative management is a reasonable alternative (Cameron, 1989). Reoperation for retained or recurrent stones can be performed with negligible operative mortality and morbidity (Girard & Legros, 1981). This report, which included many series, showed that reoperation on the CBD for retained or recurrent stones is possible, with a mortality rate of less than 2%. Miller and colleagues (1988) reported 237 patients with CBD stones treated by CBD exploration or ES. Success was higher and mortality was lower for the operatively managed group. The complication rate was similar, but the complications tended to be more serious and more apt to require surgery in the ES group. These studies show that the success, morbidity, and mortality rates of surgery are comparable to those of endoscopic approaches and suggest that operation should not be forgotten in the treatment of retained or recurrent bile duct stones.

When performing reoperation for retained CBD stones, if the stones can be adequately and completely removed, the most appropriate surgical procedure is choledocholithotomy, choledochoscopy, placement of a T-tube, and completion cholangiography. This procedure is adequate for most patients, and the overall failure rate is only 3% (Girard & Legros, 1981). Others have reported failure rates of 18% and 30% (Allen et al, 1981; Saharia et al, 1977). Allen and colleagues (1981) and Lygidakis (1982) recommended a biliary-enteric drainage procedure in all patients with previous choledocholithotomy (see Chapter 29). Tompkins and Pitt (1982) and Cameron (1989) emphasized, however, that concomitant biliary drainage should not be done as a mandatory procedure in all patients with retained or recurrent stones. In general, biliary-enteric drainage at reoperation should be carried out if any of the following occur: 1) stricture or stenosis of the distal bile duct or sphincter of Oddi, 2) marked dilation of the duct of 2 cm or more, 3) multiple or primary bile duct stones, 4) inability to remove all stones from the duct, 5) a third operation.

Transduodenal sphincteroplasty (see further on), choledochoduodenostomy, or choledochojejunostomy is effective (Braasch et al, 1980; Johnson & Harding Rains, 1978; Jones, 1978). Sphincteroplasty is rarely necessary, because ES suffices in many cases. ES is of no value, however, in the presence of a long stricture of the distal duct. Sphincteroplasty is the preferred operative approach in patients with a duct smaller than 1.5 cm in diameter to avoid possible stricture formation at the anastomosis, but it carries a greater risk of postoperative pancreatitis. Side-to-side or end-to-end choledochoduodenostomy and end-to-side Roux-en-Y choledochojejunostomy are suitable for CBDs larger than 1.5 cm and offer better decompression of an extremely large duct. The mortality rate of choledochoduodenostomy is lower than that attending transduodenal sphincteroplasty, and it has been shown to be a safe and simple operation with low morbidity and mortality, especially in elderly patients (Lygidakis, 1982; Schein & Gliedman, 1981). Occasionally, recurrent or primary stones are seen in patients with dilated ducts and a widely patent sphincter. In such cases, which also have been reported after endoscopic papillotomy, side-to-side choledochoduodenostomy or end-to-side Roux-en-Y choledochojejunostomy is necessary.

Results of Clinical Experience with Reoperation

The courses of all patients who had a reoperation for retained or recurrent choledocholithiasis at the Maisonneuve-Rosemont Hospital between 1969 and 1990 were reviewed (Girard, 2000). Eighty-five patients underwent a total of 88 operations, 43 of which were performed in patients older than age 60. Of the 88 operations, 85 were second operations, and 3 patients needed a third operation; CBD stones were confirmed in all patients before reoperation.

Three three types of bile duct reoperation were performed: choledocholithotomy with T-tube drainage (64 patients), choledocholithotomy with side-to-side choledochoduodenostomy (15 patients), and choledocholithotomy with transduodenal sphincteroplasty (6 patients). Choledocholithotomy with T-tube drainage in 1 patient and choledocholithotomy with side-to-side choledochoduodenostomy in 2 patients were performed at a third operation.

The average hospital stay was 9.3 days. No patient died despite the presence of associated risk factors in 44 patients. There were only six minor complications, and none of them necessitated urgent surgery. Two patients (3%) of the 64 who had choledocholithotomy with T-tube drainage developed recurrent bile duct stones 4 and 5 years after a second operation, and side-to-side choledochoduodenostomy was performed.

Taking Girard’s (2000) experience with that of other reported series, there have been 15 deaths among 920 patients submitted for reoperation for recurrent bile duct stones (Table 35.1). In one of these series (McSherry & Glenn, 1980

Only gold members can continue reading. Log In or Register to continue