History

The first report of radiologic visualization of the biliary tree was presented by Burckhardt and Müller in 1921, and cholecystocholangiography was achieved by percutaneous puncture of the gallbladder. The first report of PTC was by Huard and Do-Xuan-Hop in 1937, and cholangiography was performed with the suboptimal contrast agent Lipiodol. The use of transhepatic cholangiography as a diagnostic tool gained popularity 15 years later, after Carter and Saypol’s (1952) discussion of PTC with the use of a water-soluble contrast agent. In the ensuing years, many investigators (Flemma & Shingleton, 1966; Glenn et al, 1962; Mujahed & Evans, 1966; Seldinger, 1966; Shaldon et al, 1962; Weicher, 1964) described a variety of different methodologic details, including the use of sheathed or unsheathed needles of various sizes, different sites and directions of puncture, and various numbers of puncture trials to maximize success. The procedure remained associated with a significant risk of bile peritonitis, especially in obstructed systems, and the less frequent complication of hemorrhage. The last essential refinement in transhepatic cholangiography, the use of fine needle technique, was developed at Chiba University and was first presented by Ohto and Tsuchiya (1969) and later by Tsuchiya (1969). The value and decreased complication rate of the fine needle technique was verified by numerous authors (Benjamin et al, 1978; Ferrucci et al, 1976; Fraser et al, 1978; Gold & Price, 1980; Harbin et al, 1980; Hinde et al, 1977; Jain et al, 1977; Pereiras et al, 1977), and the fine needle technique has been generally accepted as the standard.

At present, diagnostic transhepatic cholangiography has been completely supplanted by noninvasive imaging techniques for the evaluation of the biliary tree. In 1985, Kadir reported that less than 5% of patients referred for evaluation of biliary disease required concomitant drainage procedures. With continued advancement of cross-sectional imaging techniques, including the development of MRI cholangiography (Park et al, 2004; Romagnuolo et al, 2003; Simone et al, 2004; Vaishali et al, 2004; Zhong et al, 2003) and CT cholangiography, diagnostic PTC should be performed only as part of a planned radiologic interventional procedure.

The most obvious benefits of noninvasive cholangiography are the elimination of complications and pain, but several other advantages are also important. Puncture and contrast injection techniques in high bile duct obstruction with isolated systems visualize only the portions of the biliary tree that are in continuity with the puncture site, and multiple interventions may be required to visualize the entire biliary tree if there are areas of duct isolation (see Fig. 18.2). Even with multiple punctures and contrast injections, cross-sectional imaging may be necessary sometimes to ensure that the biliary tree has been completely assessed. MRI cholangiography has the advantage of showing the entire biliary system even in the presence of isolation (see Fig. 18.1). Finally, there is the diagnostic advantage gained with cross-sectional imaging. By allowing visualization of many more organs than just the biliary system, diagnostic accuracy of cholangiography is significantly increased.

Preprocedural Preparation

All patients require cross-sectional imaging consisting of CT, ultrasound, or MRCP before the procedure. This imaging is especially important in patients who have undergone hepatic resection. In the authors’ institution, intravenous contrast-enhanced CT is the procedure of choice because of its ready availability and its ability to show the level of obstruction, position of the liver, presence of lobar atrophy, status of the portal veins, and relationship of bile ducts to other structures, which could greatly facilitate successful puncture.

Coagulation parameters and platelet count should be corrected when necessary. Patients generally require conscious sedation consisting of midazolam and a pain medication, such as meperidine (Demerol), fentanyl, or morphine, and they should receive only clear liquids after midnight the night before the procedure. All patients must receive broad-spectrum intravenous antibiotic coverage, and antibiotics should be administered 1 hour before the procedure to ensure maximal blood levels at the time of PTC.

Procedure

The procedure is ideally performed on a tilting fluoroscopic table. Because the specific gravity of contrast material is greater than that of bile, when the fluoroscopic table can be tilted, less contrast agent is required to fully delineate the biliary tree.

Success Rate and Accuracy

Opacification of the bile ducts is successful in 95% to 100% of patients with biliary obstruction (Mueller et al, 1981; Harbin et al, 1980; Jain et al, 1977). A success rate of 60% to 95% is reported for nondilated biliary systems. The chance of success in the nondilated system is increased by the number of needle passes performed (Jaques et al, 1980). Usually, the level of obstruction is accurately determined by careful attention to detail and liberal use of a tilt table, but the technique is less definitive for determining the cause of obstruction. No radiologic descriptions of obstructed bile ducts are pathognomonic for differentiation of benign and malignant disease (Hadjis et al, 1985; Wetter et al, 1991). Many malignant masquerades are well described, and it is not always possible to differentiate between calculous disease and papillary bile duct cancer. Other radiologic findings and cytology or histology are often required for accurate diagnosis.

Pitfalls in Interpretation

Lack of Opacification

Failure to inject adequate volume of contrast agent can lead to false localization of the level of obstruction. This can occur with complete obstruction and may be recognized by the presence of a hazy margin at the level of the apparent obstruction (Fig. 18.3; Kittredge and Baer, 1975). In high bile duct obstruction, especially when associated with variant anatomy, isolated segments of the biliary tree can be visualized only by direct puncture. If direct cholangiography is incomplete, there also may be difficulty diagnosing duct injuries and bile leaks, both of which can be missed unless the proper duct is punctured and opacified.

FIGURE 18.3 Ampullary carcinoma. A, With the patient supine, contrast pools proximally, giving a false impression of a high bile duct obstruction. The spurious nature of the level is suggested by the hazy inferior margin to the contrast column. B, With the patient sitting semierect, the contrast pools at the true point of obstruction, which is sharply defined.

Complications

Serious complications of PTC are rare and occur in approximately 3% of patients (Harbin et al, 1980). The most common major complications are bile leakage (1% to 2%), sepsis (2% to 3%), and hemorrhage (0.2% to 0.4%); much rarer complications include pneumothorax, biliothorax, colon puncture, and abscess formation. Many of these complications can be decreased and avoided. Ultrasound guidance and puncture below the ninth intercostal space will clearly decrease the incidence of pulmonary complications, and septic complications can be avoided by appropriate antibiotic coverage and by not overdistending the biliary tree. At times, aspiration and decompression of the biliary tree will be valuable in allowing injection of larger volumes of contrast agent without leading to sepsis.

History

ERCP was first reported in 1968 by McCune and colleagues and has remained an important diagnostic modality frequently used in the management of patients with hepatobiliary and pancreatic diseases (Cotton, 1977; Cotton et al, 1972; Freeney, 1988; Oi et al, 1970). Since the 1970s, there has been continued progress in ERCP instrumentation. One major innovation was the development in the late 1980s of video, or electronic, endoscopy. Video endoscopy enables high-quality photographic and videotape documentation of important endoscopic findings and has made the training of physicians in the technique of ERCP much easier. The endoscopic skills needed to perform ERCP are more difficult to learn than the standard procedures of upper endoscopy and colonoscopy, but now many endoscopists throughout the world can perform diagnostic ERCP easily, rapidly, and safely. Working with a cooperative patient and a well-trained team, this procedure often can be completed in less than 15 minutes. Diagnostic ERCP is rapidly being replaced, however, by noninvasive imaging techniques, such as MRCP.

A 2002 National Institutes of Health consensus conference on ERCP concluded that although MRCP and ERCP had similar sensitivity and specificity in diagnosing common bile duct stones, ERCP, as an invasive procedure, is more operator dependent and has risks associated with it because of the required sedation, and it carries the risk of injection pancreatitis. As a result, stand-alone diagnostic ERCP is being used much less frequently. It is most commonly combined with a therapeutic endoscopic procedure, such as endoscopic sphincterotomy and stone extraction for choledocholithiasis, or the insertion of an endobiliary stent for malignant biliary obstruction.

Technique

Patient selection is important, because ERCP is commonly done in an outpatient setting. Patients should be alert and oriented and must be able to give informed consent. In the rare situation in which this is not possible, such as with an intubated patient on mechanical ventilation, consent is obtained from the next of kin. Patients with uncorrected shock, cardiac arrhythmias, profound neutropenia, or significant coagulopathy should not have an elective diagnostic test such as ERCP performed.

Age is not a contraindication to ERCP, because the procedure is safe even for selected patients in their 90s. Although children less commonly have pancreatic and biliary disease, the standard technique is often all that is necessary for children, and instrumentation is the same except in children younger than 6 months old. General anesthesia is rarely needed for children older than 11 or 12 years (Buckley & Connon, 1990). ERCP has been shown to be a valuable adjunct in the evaluation of infantile cholestasis (Wilkinson et al, 1991). In a case-control study comparing children undergoing ERCP with adults, there were no differences in the success rate or the rate of complications (Varadarajulu et al, 2004). Elderly patients can safely undergo ERCP, and they have the same risks of bleeding and perforation as younger patients do but have a lower risk of pancreatitis.

Patient comfort is maintained by the use of intravenous sedation under monitored control. Drug combinations include narcotics such as meperidine and droperidol and the benzodiazepines midazolam or diazepam. Dosages are titrated for each patient with a total dose of meperidine generally ranging from 50 and 100 mg and midazolam between 2 and 10 mg. More recently, propofol, at 190 μg/kg/min, administered by anesthesia personnel, has been replacing meperidine and a benzodiazepine. Studies have shown that propofol is more effective than sedation with midazolam, it is safe, and it is associated with a faster postprocedure recovery (Wehrman et al, 1999). In some centers, if the endoscopic procedure is expected to be difficult, or if the patient has significant comorbid medical conditions, general anesthesia is used. Excess duodenal motility is controlled by bolus injections of 0.2 to 1 mg of intravenous glucagon. Oxygen is administered by nasal cannula to avoid the hypoxemia that has been described in 40% of patients undergoing ERCP (Woods et al, 1989). The patient’s electrocardiogram, blood pressure, oxygen saturation, and overall condition are continually monitored throughout the procedure by a dedicated nurse. Antibiotics are not given routinely for diagnostic procedures except when biliary obstruction is expected. All endoscopic equipment used for this procedure, including the endoscopes, is either chemically disinfected or gas sterilized.

A side-viewing duodenoscope is used to afford excellent visualization of the ampulla of Vater. In patients with a Billroth II type gastrojejunostomy, a standard forward-viewing upper endoscope or pediatric colonoscope may be needed to successfully approach the ampulla. An initial endoscopic evaluation of the stomach and duodenum is performed before cannulation of the ampulla. The pancreatic and biliary ducts are selectively cannulated and identified, and a contrast agent, such as diluted Renografin-60, is injected into the desired duct under fluoroscopic control, with subsequent radiographic images obtained of the duct anatomy. The use of a guidewire to cannulate the ampulla without using contrast is becoming common. In one recent series, 795 (99%) of 801 ERCPs were performed without contrast to initially identify access to the common bile duct (CBD). The pancreatitis rate in this series was 1.3%, as was guidewire perforation of the bile duct, which also occurred infrequently (Adler et al, 2010). An additional way of gaining access to the difficult-to-cannulate CBD is to selectively place a pancreatic duct stent first and then attempt wire-guided cannulation of the bile duct.

Material for pathologic and cytologic evaluation can be obtained from either the biliary or pancreatic duct system with a variety of dedicated endoscopic biopsy forceps and cytology brushes. Pathologic and cytologic material also may be obtained from the ampulla of Vater, duodenum, and stomach.

A skilled endoscopist can be expected to identify the ampulla of Vater in almost all patients with normal anatomy. If the ampulla is inside a duodenal diverticulum, or if the second portion of the duodenum is stenotic, compressed, or invaded by a pancreatic mass, identification of the ampulla may be difficult. When the ampulla is found, success rates for selectively cannulating the CBD and pancreatic duct are greater than 90% (Rosch, 1985). When difficulty occurs in cannulation of the CBD, invasive maneuvers, such as precut papillotomy, can improve the success rate but with an associated increase in the complication rate (Shakoor & Geenen, 1992). In a patient with a Billroth II gastrojejunostomy, success rates for bile duct cannulation are much lower (Katon et al, 1975; Osnes & Myren, 1975).

Endoscopy and Pancreatography during Endoscopic Retrograde Cholangiopancreatography

The ability to perform endoscopy and pancreatography in addition to cholangiography during ERCP affords a major advantage to this procedure. It is common for endoscopic examination of the stomach and duodenum to provide important diagnostic information that is helpful in management planning. Displacement of the antrum or pylorus or a stricture or narrowing of the second portion of the duodenum may indicate the presence of a pancreatic mass responsible for obstructive jaundice. The diagnosis can be confirmed by biopsy and cytologic specimens taken during the procedure from the infiltrated or ulcerated duodenal wall.

Duodenal diverticula almost always are located near the papilla in the descending duodenum. Large juxtapapillary diverticula are clinically significant, because they are often associated with choledocholithiasis. Although it was thought that periampullary diverticula may make cannulation of the ampulla more difficult, more recent work has shown that this may not be true (Tham & Kelly, 2004). On inspection of the ampulla, anatomic variants should be looked for before attempting cannulation (Phillip et al, 1974). Occasionally, two orifices are found, and this indicates separate biliary and pancreatic duct systems. The minor ampulla is located about 1 to 2 cm above the major papilla. Impacted gallstones give rise to a characteristic distension or bulge of the papilla, and previous spontaneous passage of bile duct stones can be recognized by a fissured splitting of the papillary orifice. Previous surgical dilation of the papilla or spontaneous gallstone perforation above the papilla also produces a characteristic appearance. Occasionally, a fistulous perforation in the roof of the papilla is found as a result of a false passage produced at surgical dilation (Tanaka & Ikeda, 1983). Biliary–enteric anastomoses appear as circular or slitlike openings.

The endoscopic diagnosis of ampullary carcinoma is not difficult, especially if the tumor is exophytic. The diagnosis becomes more challenging, however, when the tumor is predominantly intramural. In such instances, the diagnosis is frequently confirmed by biopsy and cytologic specimens, after endoscopic papillotomy allows the tumor to be exposed. In a series from the Medical College of Wisconsin, the correct diagnosis was made by endoscopic biopsy in 42 of 44 patients with ampullary neoplasia and in 16 of 18 patients with invasive ampullary cancer (Komoroski et al, 1991).

Imaging the pancreatic duct can be an important adjunct to cholangiography during ERCP. Strictures, stones, and other obstructing lesions can be identified. With increasing age comes progressive atrophy and fibrosis of the pancreas. The diameter of the main pancreatic duct also increases with age, although one study found no difference in pancreatic duct length among patients younger than 40 years compared with older patients. Duct diameter throughout the pancreas was significantly greater, however, in patients over 40 (Anand et al, 1989).

Anatomic variations, such as pancreas divisum (Fig. 18.4), also may be identified on a pancreatogram. This abnormality has been described in 7.5% of ERCP procedures and can be confirmed by cannulation of the main pancreatic duct through the orifice in the minor papilla (Bernard et al, 1990).

FIGURE 18.4 Pancreas divisum. The cannula is in the major papillary orifice, and contrast injection opacifies the proximal portion of the major pancreatic duct (Wirsung). Injection through the minor papillae allows opacification of the duct of Santorini and the distal duct of Wirsung.

Complications

The experience of the endoscopist is one of the most significant factors related to the development of ERCP complications (Bilbao et al, 1976). Statistics on complication rates vary accordingly. High case volume also has an impact on the complication rate. In a study conducted in Austria, endoscopists performing more that 50 ERCP procedures per year were compared with on those performing fewer than 50 per year. Those in the higher case volume group had a significantly higher success rate (86.9% vs. 80.3%; P < .001) and a lower overall complication rate (10.2% vs. 13.6%, P = .007; Kapral et al, 2008).

Acute pancreatitis after ERCP occurs in less than 7% of patients (Christensen et al, 2004; Rosch et al, 1981) and should be distinguished from transient asymptomatic hyperamylasemia, which occurs in 40% to 75% of cases (Classen & Demling, 1975). Asymptomatic hyperamylasemia disappears within 1 to 2 days, as do hypertrypsinemia (Phillip & Hagenmuller, 1983) and elevations of serum lipase and elastase 1 levels (Okuno et al, 1985). Radiographic documentation of renal excretion of the contrast agent injected into the pancreatic duct does not predict the development of acute pancreatitis (Hopper et al, 1989), and necrotizing pancreatitis, a serious complication, is observed in about 0.1% of pancreatograms. The prevalence of post-ERCP pancreatitis in children is quite low, about 2.5% in one study (Iqbal et al, 2008).

The use of nonionic contrast medium of low osmolarity has shown no advantage over the less expensive ionic contrast medium in preventing ERCP-related pancreatitis (Hannigan et al, 1985). The risk of pancreatitis is reduced by careful and gentle injection of the contrast medium into the pancreatic duct, by avoiding overdistension or “acinarization” of the pancreatic duct, and by minimizing repeated injection of the pancreatic duct when encountering difficulty in filling the CBD. Prophylactic administration of somatostatin or its analog octreotide has not been shown to prevent pancreatitis during diagnostic or therapeutic ERCP (Borsch et al, 1984; Sternlieb et al, 1992). A large, prospective, randomized, placebo-controlled study from Italy looked at the efficacy of somatostatin and gabexate in preventing post-ERCP pancreatitis; 966 patients were studied, and no difference in the rate of pancreatitis was observed between the groups (Andriulli et al, 2004). A randomized control study demonstrated that 24 hours of octreotide prophylaxis before ERCP significantly decreased the incidence of post-ERCP pancreatitis compared with a placebo group (2/100 [2%] vs. 9/101 [8.9%]; P = .03) (Thomopoulos et al, 2006). Other investigators have suggested that when injection pancreatitis is a possibility, the use of a temporary pancreatic duct stent may serve to prevent its occurrence (Singh et al, 2004). In addition, when pancreatitis has developed, the use of somatostatin does not improve its clinical course (Phillip et al, 1985).

A serious complication of ERCP is the development of postprocedure cholangitis. This condition occurs most commonly when there is a significant and high-grade bile duct obstruction. When an obstructed bile duct is identified on ERCP, it is important to treat the obstruction rapidly by nonsurgical or surgical means (Classen & Phillip, 1982). Although no studies confirm the benefit of prophylactic antibiotics, it is reasonable to administer intravenous antibiotics that are preferentially excreted from the liver into the bile until adequate biliary drainage is achieved.

One study looked at the prophylactic use of antibiotics in routine ERCPs (Sauter et al, 1990). The authors found no difference in cholangitis rates when antibiotics were used, although the frequency of procedure-related bacteremia was significantly reduced. Antibiotics added to the injected radiographic contrast medium are of no benefit (Jendrzejewski et al, 1980). In addition, it was found that endoscopic instruments used in ERCP can be the source of serious infections (Earnshaw et al, 1985). Salmonella species are the most common organisms transmitted by contaminated endoscopes (Axon, 1991), and for this reason, it is imperative to ensure that the endoscopic equipment used for ERCP is adequately disinfected or sterilized.

Biliary Anatomy

The anatomy of the bile ducts is discussed in Chapter 1A, Chapter 1B . Knowledge of the common variations of ductal branching is essential for accurate interpretations of cholangiograms, and these are shown in Figures 18.5 and 18.6; segmental nomenclature is summarized in Table 18.1. In the right lobe, the posterior segments lie more laterally than the anterior segments, so that the most lateral ducts on a cholangiogram are usually segments VI inferiorly and VII superiorly. The posterior sectoral duct is often recognizable by an arched course near the confluence (Figs. 18.7 and 18.8B). A right sectoral duct crosses to the left to join the left hepatic duct in 28% of cases according to Healey and Schroy (1953); in 22%, this is the posterior sectoral duct (see Figs. 18.6B and 18.8B), and in 6%, this is the anterior duct (see Figs. 18.6C and 18.8D). Occasionally, a right sectoral or segmental duct, posterior more often than anterior, courses inferiorly and enters the common hepatic duct directly (Fig. 18.9). The confluence of the right and left ducts takes the form of a trifurcation rather than a bifurcation in 12% of cases according to Couinaud (1957; see Fig. 18.6A).

FIGURE 18.5 Standard intrahepatic ductal anatomy. The segments are numbered according to Couinaud’s description (see Table 18.1). CHD, common hepatic duct; LHD, left hepatic duct; RASD, right anterior sectoral duct; RHD, right hepatic duct; RPSD, right posterior sectoral duct.

FIGURE 18.6 Variations of perihilar ductal anatomy. CHD, common hepatic duct; LHD, left hepatic duct; RASD, right anterior sectoral duct; RHD, right hepatic duct; RPSD, right posterior sectoral duct.

Table 18.1 Segmental Nomenclature

FIGURE 18.7 Hilar cholangiocarcinoma involving first-order right hepatic duct, proximal common hepatic duct, and faintly opacified left hepatic duct (arrowhead). Note the characteristic arched course of the right posterior sectoral duct (arrow).

FIGURE 18.8 Postcholecystectomy strictures graded according to Bismuth. A, Grade I (>2 cm from the confluence of the right and left hepatic ducts; arrowheads): calculi lie above and below the stricture (arrow). B, Grade II (<2 cm from the confluence): there has been a previous hepatojejunostomy; the right posterior sectoral duct (arrowhead) has an exaggerated arched course and enters the left hepatic duct as a normal variant. C, Grade III (the confluence is involved by stricture, but the right and left hepatic ducts are not completely separated): ducts of segment II (white arrow) and segment III (black arrow) join the confluence independently as a normal variant. D, Grade IV (the right and left ducts are separated by the stricture): the right anterior sectoral duct (A) is draining into the left hepatic duct (L), which is separated from the right posterior sectoral duct (P) by the stricture (arrows).

FIGURE 18.9 Pancreatitis producing a typical, incomplete long stricture of the common bile duct. The right posterior sectoral duct has a low entrance into the common hepatic duct, an uncommon but important normal variant.

In the left lobe, the superior and inferior lateral segment ducts, segments II and III, unite in the line of, or to the right of, the umbilical fissure in 92% of cases. In the latter instance, the quadrate lobe, segment IV, may drain wholly or partially into the segment II duct. Rarely, segment II and III ducts join at or close to the confluence (see Figs. 18.6E and 18.8C), and segment IV drains directly into the common hepatic duct in 1% of cases (see Fig. 18.6F; Healey & Schroy, 1953).

The caudate ducts are often difficult to identify. Usually two or three ducts drain most commonly into the right posterior sectoral duct, right hepatic duct, or left hepatic duct (Healey & Schroy, 1953). The recognizable caudate ducts are usually a few centimeters long and drain downward or to the right.

The left hepatic duct (average length, 17 mm) is considerably longer than the right hepatic duct (average length, 9 mm) and has a longer extrahepatic course. The normal diameters of the main bile ducts as measured at PTC are shown in Table 18.2. These figures are greater than the true duct dimensions because of some distension produced by direct cholangiography together with considerable magnification occurring on any fluoroscopic “spot film.” The magnification is of the order of 40% (Nichols & Burhenne, 1984) and affects all structures in the image, including calculi, tubes, and strictures.

Table 18.2 Average Duct Diameters Measured Directly from 50 Normal Percutaneous Transhepatic Cholangiography Examinations

From Okuda K, et al, 1978: Frequency of intrahepatic arteriovenous fistula as a sequela to percutaneous needle puncture of the liver. Gastroenterology 74:1204-1207.

The upper limits of normal for the diameter of the extrahepatic bile ducts as measured by ERCP vary between 9 mm and 14 mm (Niederau et al, 1984). Combined radiologic and manometric studies (Poralla et al, 1985) have shown that even in the absence of extrahepatic cholestasis, the diameter of the bile ducts and the pressure difference therein increases with advancing age. The diameter of the bile ducts as measured by ultrasonography is less than those measurements obtained during ERCP (Niederau et al, 1984). Anatomic abnormalities of the hepatobiliary system include cystic dilations (Fig. 18.10) of the bile duct or of the intrahepatic bile ducts (Caroli disease; see Chapter 46). There is a wide variation in where the cystic duct joins the common hepatic duct. A low junction with a correspondingly long cystic duct (Fig. 18.11) may result in difficulties if not recognized,. This is especially true when a cholecystojejunostomy is performed as a palliative biliary bypass for carcinoma of the head of the pancreas, and the jaundice either is not relieved or recurs rapidly in the postoperative period.

FIGURE 18.10 Choledochal cyst.

FIGURE 18.11 Long cystic duct.

Interpretations

Because of its inherent weakness of only allowing visualization of the bile duct lumen, the main problem with the use of direct cholangiography is its lack of specificity. There are few, if any, pathognomonic radiologic findings. Many disease entities, from benign to malignant, overlap greatly in their cholangiographic appearances. The combination of history, blood markers, associated radiologic findings, and clinical scenario can often significantly narrow the differential diagnosis. However, it must be stressed strongly that because the cholangiographic appearance of many biliary diseases may be indistinguishable, biopsy is often required to rule out malignancy or to confirm suspected diagnosis.

Bile Leaks

Bile leaks are seen as sites of free extravasation of contrast agent at a site of bile duct injury. Injury may be secondary to trauma, but most commonly it is iatrogenic in nature. Associated bilomas may be seen at the point of bile leak. Although puncture or opacification of the correct duct is necessary for diagnosis, this is perhaps the remaining diagnostic scenario in which invasive direct cholangiography has a distinct advantage over noninvasive techniques. Because leaking intrahepatic bile ducts are usually not dilated, nonvisualization and inability to localize this finding on MR and CT cholangiography is common. Cystic duct leaks, minor injuries to extrahepatic bile ducts, and leaking anastomoses may also be unidentifiable and nonlocalizable with indirect techniques. Diagnosis and localization of bile duct leaks is therefore perhaps the only remaining indication for direct cholangiography.

Filling Defects

Air Bubbles, Blood Clots, Calculi, Primary and Secondary Bile Duct Cancers, and Parasitic Diseases

Air bubbles, though confusing, most commonly declare themselves by their perfectly circular shape and their distribution to nondependent structures. Blood clots in the bile duct are seen more frequently with PTC than with ERCP. Hemobilia can sometimes take more than 48 hours to resolve, and when it is more severe; it can be castlike and may mask other filling defects.

Calculous disease (see Chapters 36, 37, and 39) remains the most common filling defect in the biliary system. Distinguishing characteristics of gallstones and primary bile duct calculi include a faceted radiologic appearance and disposition to move to gravity-dependent positions. Calculi may be seen as discrete filling defects (Figs. 18.12 and 18.13) or castlike structures filling entire ducts, as occurs in oriental cholangiohepatitis, cystic diseases of the bile ducts, or even proximal to strictures of any etiology. Impacted calculi may be difficult to differentiate from strictures or tumors.

FIGURE 18.12 Choloedocholithiasis.

FIGURE 18.13 Benign stricture of the right hepatic duct (arrow) with multiple ductal calculi proximal to it. The hepatojejunostomy is partially strictured.

Primary bile duct cancer (see Chapter 50A, Chapter 50B, Chapter 50C, Chapter 50D ), specifically papillary cholangiocarcinomas, can also present as cholangiographic filling defects (Fig. 18.14). T-shaped filling defects may also be detected (Torok & Gores, 2001; Fig. 18.15), and papillary bile duct cancers may cause filling defects as a result of mucin production (Fig. 18.16). Other malignancies, including melanoma and intraductal metastases, such as colon cancer, are also more unusual causes of cholangiographic filling defects (Riopel, 1997).

FIGURE 18.14 Papillary hilar cholangiocarcinoma (arrowheads). Only the right ducts are opacified.

FIGURE 18.15 “Golf tee” appearance of a papillary bile duct cancer (arrow) involving the common hepatic duct.

FIGURE 18.16 Nasobiliary cholangiogram opacifying left hepatic ducts. Main left hepatic duct contains a small mucin-secreting papillary cholangiocarcinoma (arrow). The mucin results in expansion of the common bile duct below the tumor and appears as strandlike filling defects.

(Courtesy Dr. A. Speer.)

Parasitic infections (see Chapter 45), such as with hydatid disease or with Ascaris lumbricoides or Clonorchis sinensis, are diseases with worldwide distribution that can also present cholangiographically as intraductal filling defects. A proportion of hepatic hydatid cysts (5% to 10%) rupture into the bile ducts and may simulate choledocholithiasis (see Chapter 68). Calcified cysts are easy to recognize on radiographs, and daughter cysts can cause biliary obstruction. When the calcified cyst is not obvious, biliary strictures with obstruction may be noted on cholangiogram. The biliary ducts can show considerable irregularities in caliber and extensive displacement of the intrahepatic branches secondary to the mass effect of a large hydatid cyst (Cottone et al, 1978; Dyrszka & Sanghavi, 1983; Ibrahim & Kawanishi, 1981).

Ascaris lumbricoides is a commonly seen helminth that has worldwide distribution. Its prevalence is 90% in some parts of Africa and Asia. If the worm passes through the sphincter of Oddi, it may cause acute pancreatitis or a cholestasis syndrome (Winters et al, 1984). In the acute stage, the worm occasionally may be found and extracted from the ampulla, and it can be detected in the biliary tract by cholangiography.

Eating raw meat has been associated with Clonorchis sinensis infestation. The prevalence of this disease has been estimated to be 60% of the general population of Hong Kong based on stool ova examinations. This worm can penetrate through the papilla into the bile ducts. In an ERCP study of 31 consecutive patients, the typical filamentous, wavy, or elliptical appearance of the worm in the bile ducts was believed to be pathognomonic. Other common cholangiographic findings include widely dilated extrahepatic bile ducts, which are filled with biliary sludge and stones, and intrahepatic duct strictures, which are predominantly found in the branches of the left hepatic duct (Yellin & Donovan, 1981). The eggs of C. sinensis act as a nucleus for the development of the bile duct stones (Lam et al, 1978). Naval and colleagues (1984) reported successful endoscopic biliary lavage to eliminate the eggs.

Invasion of Fasciola hepatica into the biliary tract also may cause serious lesions. In the chronic stage, F. hepatica infection can resemble sclerosing cholangitis (Hauser & Bynum, 1984). The appearance on ERCP is that of dilated bile ducts with unexplained sludge in the distal bile duct (Figs. 18.17 and 18.18).

FIGURE 18.17 Liver flukes in the distal bile duct presenting as “biliary sludge.”

FIGURE 18.18 Extracted liver flukes (same patient as in Figure 18.34).

Cystic Diseases

Typing of choledochal cysts (see Chapter 46) is according to the Todani et al (1977) classification. Type 1 cysts, the most common kind (80% to 90%), manifest as a fusiform dilation of the CBD, common hepatic duct (CHD), or both (see Figs. 18.10 and 18.19). A type 2 cyst (2% to 3%) is seen as a diverticular outpouching of the CBD or CHD. A type 3 cyst, also referred to as choledochocele, is a dilation of the intraduodenal (mural) portion of the distal CBD. Type 4 cysts (10% to 15%) have intrahepatic and extrahepatic cystic components in any combination, and type 5 cysts, also known as Caroli disease, is a rare form in which cysts are only seen in the intrahepatic bile ducts. Although most patients with choledochal cysts are diagnosed in infancy or childhood, 20% to 30% are diagnosed as adults. Associated calculous diseases secondary to bile stasis or stricture are frequently seen with cystic diseases. However, these must be differentiated from other more significant entities, such as bile duct cancers, because of the marked predisposition of biliary malignancies in patients with choledochal cysts (Fig. 18.20).

FIGURE 18.19 Choledochal cyst with intrahepatic cyst formation (arrowhead). The common bile duct has an abnormally proximal junction with the pancreatic duct (arrow).

FIGURE 18.20 Cholangiocarcinoma within a choledochal cyst.

Bilomas, saccular intrahepatic contrast collections, may be secondary to occlusive disease or trauma, including iatrogenic trauma and trauma from transarterial chemoembolization (TACE) (Sakamito et al, 2003; Kim et al, 2001). Particularly in occlusive disease, bilomas can become infected and may appear as abscesses. Microabscesses seen with suppurative cholangitis typically appear as grapelike clusters in terminal bile ducts (Fig. 18.21).

FIGURE 18.21 Multiple hepatic abscesses associated with suppurative cholangitis in a patient with hilar duct obstuction.

Strictures

Bile duct strictures may be classified by their morphologic appearance or level of obstruction. Level of obstruction classification, as described by Bismuth and colleagues (1992), has significant surgical implications. When used strictly for etiologic diagnosis, however, neither level of obstruction nor morphologic appearance description is as clinically rewarding. Cholangiographic strictures are present in a diverse group of diseases. Many benign and malignant conditions can have strictures that encompass the entire gamut of cholangiographic appearances. Any combination of intrahepatic or extrahepatic distribution, shouldered or smooth, beaded or nonbeaded, long or short, and with or without associated proximal dilation has been described in most of these diseases. Diagnostic limitations of direct cholangiography are due to this great overlap in findings. Visualization of only the bile duct lumen, as achieved with direct cholangiography, offers no advantages over noninvasive imaging techniques when evaluating bile duct strictures. Direct cholangiography is generally reserved for when concomitant biliary intervention is anticipated. In much of the diagnostic spectrum of stricture disease, biopsy is frequently required to rule out malignancy.

Sclerosing cholangitis (see Chapter 41) can produce cholangiographic changes in the intrahepatic and extrahepatic biliary trees, and it is commonly seen in both (La Russo, 1984). The bile ducts in primary sclerosing cholangitis (PSC) are characterized by an annular concentric stenosis, usually multifocal, with areas of normal or mildly dilated ducts between strictures (Fig. 18.22; Rogers et al, 1972). Larger bile ducts can appear beaded (Fig. 18.23), and other radiologic findings include a “prune tree” appearance, from reduction of peripheral bile duct radicles, and diverticular outpouchings of the extrahepatic bile ducts (Gulliver et al, 1991; La Russo et al, 1984; Fig. 18.24). Ulcerative colitis is identified in as many as 70% of patients with PSC, and coexisting cholangiocarcinoma can occur in 15% of these patients (MacCarty et al, 1985; Crippin & Lindor, 1992). Detecting a cholangiocarcinoma in a background of sclerosing cholangitis is difficult. Cholangiographic features suggesting cholangiocarcinoma include progressive focal stricturing, the presence of uniform proximal duct dilation, and nodular filling defects (Li-Yeng & Goldberg, 1984). It has been suggested that evaluating these features together with cross-sectional imaging can detect many tumors (Campbell et al, 1998). Again, biopsy is generally required for definitive diagnosis.

FIGURE 18.22 Sclerosing cholangitis producing a stricture of the common hepatic duct extending into second-order ducts bilaterally. Differentiation from cholangiocarcinoma is aided by fine-needle aspiration cytology (arrow). Note the right posterior sectoral duct (arrowhead) entering the left hepatic duct.

FIGURE 18.23 Primary biliary sclerosis with typical irregularity and beading of large ducts.

FIGURE 18.24 Sclerosing cholangitis with multiple intrahepatic and extrahepatic segments of stricturing. A characteristic “diverticulum” (arrow) overlies the confluence of the right and left hepatic ducts.

Cholangiocarcinoma (see Chapter 50A, Chapter 50B, Chapter 50C, Chapter 50D ) is commonly seen as the classic sclerosing Klatskin type with a high-grade Y-shaped obstruction involving the right and left main bile ducts and the proximal common hepatic duct (see Fig. 18.7). Extension of stenoses to subsegmental bile ducts is frequently seen, and biliary dilation proximal to the obstruction is expected, as is a decompressed gallbladder. Klatskin tumors may cause obstruction of adjacent portal veins, resulting in hepatic atrophy that manifests itself cholangiographically as dilated, tortuous, or even beaded, crowded bile ducts (Fig. 18.25).

FIGURE 18.25 Hilar cholangiocarcinoma with crowded left ducts indicating left lobe atrophy. The right ducts are opacified by a percutaneous transhepatic drainage catheter.

Like central lesions, the more common (60%) peripheral bile duct cancers are demonstrated in direct cholangiography as nonspecific stenoses or obstructions (Longmire et al, 1973; Ohto et al, 1980; Tompkins et al, 1981; Warren et al, 1972). They may also present with bilevel obstruction as a result of central lymphadenopathy. The additional diagnostic benefits of CT and MR cholangiography make these noninvasive techniques preferable for preprocedural planning and in differential diagnosis (Tompkins et al, 1990; Stroszczynski & Hünerbein, 2005).

Direct cholangiography for the diagnosis of gallbladder cancer (see Chapter 49) is rarely required. Gallbladder cancer is best diagnosed with CT, ultrasound, or MRI. Cross-sectional imaging reveals the common radiologic findings of associated calculous disease and direct extension of tumor into the adjacent hepatic parenchyma. Findings in direct cholangiography consist of high-grade stricture or occlusion of the biliary tree at any level (Fig. 18.26), typically with no visualization of the cystic duct or gallbladder.

FIGURE 18.26 Gallbladder carcinoma involving right third-order ducts and deviating upper common hepatic duct medially (arrowheads). Multiple small calculi appear in the gallbladder fundus (arrow), which is separated from the strictured ducts by the tumor.

Approximately two thirds of pancreatic cancers occur in the region of the papilla of Vater and the head of the pancreas, and the bile duct is usually involved (see Chapter 58A, Chapter 58B ). Characteristic cholangiographic findings include occlusion of the distal CBD with proximal dilation. The CBD above the occlusion may have a more horizontal course (Freeney, 1988; Fig. 18.27). Cystic duct patency is often preserved, and dilation of the gallbladder may be marked. ERCP, CT, and MRI may show occlusion or stenosis of the main pancreatic duct with proximal pancreatic duct dilation. The more classic double-duct sign of simultaneous obstruction of the pancreatic duct and CBD at proximate levels is also best determined with these techniques (Fig. 18.28).

FIGURE 18.27 Two of the common appearances of carcinoma of the pancreas. A, Rounded obstruction with characteristic horizontal common bile duct. Note the coincidental stones in the distended gallbladder. B, Tapered obstruction with slight shouldering. Compare this with pancreatitis (see Figure 18.9), in which shouldering tends to be absent.

FIGURE 18.28 Double-duct sign, stenosis of the bile duct and pancreatic duct, in a case of pancreatic carcinoma.

Periampullary cancer (see Chapter 59) also causes obstruction of the CBD at the level of the papilla of Vater. The site of origin may be the duodenum or distal bile duct, which is indeterminate cholangiographically. A short-segment obstruction with proximal dilation most often identified though more central biliary abnormalities could also be seen (Fig. 18.29). A polypoid filling defect may also occasionally be seen with periampullary cancers. The filling defect, however, is not pathognomonic and must be differentiated from other possible malignancies or filling defects.

FIGURE 18.29 Periampullary carcinoma producing localized stricture of distal common bile duct (white arrow) indistinguishable from pancreatic cancer. Stricturing of the upper common hepatic duct (black arrow) is due to porta hepatis lymphadenopathy.

Malignant bile duct obstruction has also been described with metastatic colon, breast, lung, and gastric cancers (Fig. 18.30). Obstructions can be intrahepatic and/or extrahepatic and may be due to lymph node involvement or direct extension (Lokich et al, 1987). Bile duct obstruction from lymphoma is more commonly extrahepatic, and extrahepatic bile duct strictures can also be seen with benign lymph node enlargements such as in Castleman disease (Przkora et al, 2003).

FIGURE 18.30 Hilar obstruction from metastatic breast cancer.

The conundrum of “malignant masquerade” (see Chapter 42A, Chapter 42B ) present with direct cholangiography is perhaps most classically demonstrated by Mirizzi syndrome (Hadjis et al, 1985; Clemett & Lowmann, 1965; Becker et al, 1994), which occurs when a gallstone is impacted in the cystic duct or gallbladder neck, causing inflammatory obstruction of the common hepatic duct. The obstruction may be limited and focal or may extend into the intrahepatic bile ducts. On cholangiogram the syndrome is indistinguishable from cholangiocarcinoma, gallbladder cancer, or other malignant strictures (Figs. 18.31 and 18.32).

FIGURE 18.31 Mirizzi syndrome. A large gallbladder calculus has eroded into the common hepatic duct (arrow), which is narrowed and deviated medially.

FIGURE 18.32 Mirizzi syndrome. A, Endoscopic retrograde cholangiopancreatography shows common hepatic duct stricture resulting from gallstone in a Hartmann pouch of the gallbladder. B, CT scan shows the impacted stone. An associated gallbladder cancer is also shown.

Oriental cholangiohepatitis (see Chapter 44) is generally seen in Asian populations. Cholangiography demonstrates strictured intrahepatic or extrahepatic bile ducts with markedly dilated proximal bile ducts. The dilated proximal bile ducts are packed with filling defects, which represent pigmented stones. Although all segments of the biliary tree can be involved, disease in the lateral segment of the left lobe is most common (Lim, 1991). Oriental cholangiohepatitis is characterized by recurrent episodes of cholangitis and is therefore commonly referred to as recurrent pyogenic cholangitis.

Acute pancreatitis (see Chapter 54) is usually diagnosed by combination of history, serum chemistry (amylase and lipase elevation), and cross-sectional imaging. Direct cholangiography, especially ERCP, is rarely performed during an acute episode because of the possibility of exacerbation of disease or introduction of infection. Once the episode has subsided, ERCP can be performed and may demonstrate a distal stricture and possible choledocholithiasis (Fig. 18.33). Care must be taken, however, as pancreatic cancer and periampullary cancer can not only have similar cholangiographic appearances but may coexist or even present clinically as acute pancreatitis (Mujica et al, 2000; Murakami et al, 2006; Akatsu et al, 2008).

FIGURE 18.33 Acute pancreatitis with pseudocyst in the head of the pancreas (verified on operation), leading to cholestasis.

In chronic pancreatitis as in acute pancreatitis, distal bile duct stricture is the most common cholangiographic abnormality, seen in approximately 25% of patients with chronic pancreatitis (Fig. 18.34; see Chapter 42A, Chapter 42B, Chapter 55A, Chapter 55B ). Stricture length and morphology are variable, and the frequently described long, smoothly tapered stenosis occurs in only 27% to 56% of patients (Stolte et al, 1984). MRI and ERCP have greater sensitivity than PTC in chronic pancreatitis because of their ability to demonstrate pancreatic duct abnormalities such as enlargement, ectasia, beading, and the presence of chronic pseudocysts. The development of a pseudocyst can also cause pressure obstruction of more central segments of the bilinear tree.

FIGURE 18.34 Filiform stenosis caused by chronic pancreatitis.

Hepatic artery infusional chemotherapy via hepatic artery infusion pump (HAIP) and with transarterial chemoembolization have both been implicated as causes of biliary sclerosis (Kim et al, 2001; Brown et al, 1997). Stricture formation is due to either direct action of the chemotherapeutic agent or from ischemia secondary to damage of the arterial vasculature supplying the bile ducts. Chemotherapy-induced biliary sclerosis (CIBS) secondary to HAIP most commonly presents cholangiographically as high-grade obstruction of the common hepatic duct (50%) indistinguishable from a Klatskin tumor. Frequently, the area of CHD obstruction takes on a fuzzy, striated, ill-defined appearance (Fig. 18.35); peripheral stenoses may also be seen but are not always present. Biloma formation with or without associated infection (abscess) is not uncommon and may be due to peripheral bile duct necrosis.

FIGURE 18.35 Chemotherapy-induced biliary sclerosis (CIBS) from hepatic artery infision pump (HAIP) therapy. Note catheter portion of pump (arrowhead) and fuzzy, striated appearance of commom hepatic duct stenosis.

Patients with AIDS may have bile duct inflammation from opportunistic infections such as cytomegalovirus and Cryptosporidium. The most common radiologic findings are gallbladder and bile duct wall thickening that are not demonstrated with direct cholangiography. Direct cholangiographic findings in AIDS-related cholangitis are very similar to those seen in sclerosing cholangitis: multiple strictures with intervening areas of dilation, beading, and even prune-tree appearances have been described (Farman et al, 1994; Schneiderman et al, 1987; Texidor et al, 1991; Miller et al, 1996).