Endoscopic Retrograde Pancreatography

CLINICAL GASTROENTEROLOGY AND HEPATOLOGY 2009;7:931–943

CLINICAL IMAGING Endoscopic Retrograde Pancreatography OLGA BARKAY, EVAN L. FOGEL, JAMES L. WATKINS, LEE McHENRY, GLEN A. LEHMAN, and STUART SHERMAN Division of Gastroenterology and Hepatology, Indiana University Hospital, Indianapolis, Indiana

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ince its introduction in 1968,1 endoscopic retrograde cholangiopancreatography (ERCP) has become an integral part of gastroenterological practice. During ERCP, a side-viewing endoscope is passed through the mouth to the duodenum, the papilla is identified and cannulated, and radiographic contrast material is injected into the bile duct and/or pancreatic duct under fluoroscopic guidance. Like biliary endoscopy, endoscopic retrograde pancreatography (ERP) has evolved from being only a diagnostic procedure to frequently a therapeutic one, providing patients with a minimally invasive method to treat selected pancreatic diseases that previously required open surgery. However, fear of complications, particularly pancreatitis, has prevented some endoscopists from applying techniques used in therapeutic cholangiography for treatment of pancreatic disorders.2 Therefore, ERP with associated therapy is mostly performed in expert centers. In this review, we will focus on the normal and abnormal pancreatic ductal anatomy, indications for ERP, and techniques to optimize the acquisition and interpretation of pancreatographic images. Discussion of pancreatic endotherapy and its complications is beyond the scope of this review.

Normal Ductal Anatomy and Variants The pancreatic ductal system consists of the ventral duct and the dorsal duct. These ductal systems arise from the ventral and dorsal pancreas anlage, respectively. The 2 ducts commonly fuse in the head region, forming the main pancreatic duct (or duct of Wirsung), draining through the major papilla, and the accessory duct (or duct of Santorini), draining through the minor papilla. The embryologic dorsal and ventral pancreatic buds come together as a result of asymmetric rotation of the developing duodenum. The ventral bud (which also gives rise to the hepatobiliary system) rotates with the gut, passing behind the duodenum from the right to left, and eventually fuses with the dorsal bud by about the seventh week of gestation (Figure 1). Failure of fusion of the ventral and dorsal duct systems occurs in approximately 10% of individuals, resulting in pancreas divisum. There are 2 types of pancreas divisum. In complete pancreas divisum, a small ventral duct drains through the larger major papilla, and the larger dorsal duct drains through the smaller minor papilla. In some cases, the entire pancreatic ductal system drains through the minor papilla via the dorsal duct. Approximately 15% of pancreas divisum cases are of the incomplete type in which a small branch of the ventral duct communicates with the dorsal duct. However, drainage of pancreatic juice is predominantly via the minor papilla. The clinical implications of incomplete pancreas divisum, therefore, are the same as for complete pancreas divisum,

except that incomplete to full visualization of the dorsal duct might occur with vigorous major papilla contrast injection. In patients with pancreas divisum, the terminology used to name the ductal structures is based on the embryologic origin; the dorsal duct arises from the dorsal pancreas, and the ventral duct arises from the ventral pancreas. A “reverse” divisum also can occur in which there is an isolated small segment of dorsal duct. This occurs when the accessory duct of Santorini does not connect with the genu of the main pancreatic duct. This anatomic variant might have physiologic significance in that an alternate pathway of pancreatic juice drainage is absent. Thus, a gallstone impacted at the major papilla will likely cause more severe pancreatitis. In addition, non-filling of the duct of Santorini can mimic malignant obstruction. Annular pancreas is a rare congenital anomaly that arises from failed or incomplete rotation of a portion of the ventral pancreas during embryologic development. In this anomaly, a branch of the ventral pancreas passes posteriorly to the descending duodenum and encircles approximately three fourths of the descending duodenum. This typically produces a ringlike narrowing of the descending duodenum between the major and minor papillae. The narrowing might be subtle enough to be missed initially if the endoscopic examination is not conducted carefully. Whereas children with annular pancreas tend to present with symptoms of gastric outlet obstruction, adults do so less frequently, although typically the duodenal bulb is enlarged. More commonly, adult patients present with abdominal pain or pancreatitis, perhaps as a result of the association with pancreas divisum, which is present in approximately one third to one half of patients.3,4 The relationship between the annular pancreas and duodenal obstruction is well known; the relationship between pancreatitis and annular pancreas is less certain, particularly in patients without pancreas divisum. Ansa pancreatica is an uncommon type of ductal anatomic variation in which the main pancreatic duct forms a loop, usually in the head or neck of the pancreas. This anatomic variant can make wire passage for therapeutic maneuvers inAbbreviations used in this paper: CT, computed tomography; ERCP, endoscopic retrograde cholangionpancreatography; ERP, endoscopic retrograde pancreatography; EUS, endoscopic ultrasound; IPMN, intraductal papillary mucinous neoplasm; LOCM, low osmolality contrast media; MRCP, magnetic resonance cholangiopancreatography; MRI, magnetic resonance imaging. © 2009 by the AGA Institute 1542-3565/09/$36.00 doi:10.1016/j.cgh.2009.06.002

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creas divisum and also allows minor papilla endotherapy to be performed in symptomatic patients. (3) ERP before tissue sampling. A tissue sample can be obtained from the pancreatic duct by using a cytologic brush, biopsy forceps, fine-needle aspiration catheter, or by pancreatic juice aspiration. There is limited evidence suggesting that tissue sampling of a pancreatic stricture has a higher diagnostic yield than sampling a biliary stricture in patients with pancreatic cancer.8 ERP combined with pancreatoscopy is a promising tool in establishing the diagnosis of IPMN by direct endoscopic visualization and tissue sampling of suspicious lesions.9 (4) ERP in the diagnosis of chronic pancreatitis. ERP is an insensitive test to diagnose early stage chronic pancreatitis. However, when combined with intraductal secretin test, the yield appears better.10 ERP is rarely used for

Figure 1. Anatomy and embryology of normal pancreas and pancreas divisum.

volving the pancreas upstream to the loop very difficult, but otherwise it does not seem to have any clinical significance. Some anatomic variants of the pancreatic ductal anatomy are schematically represented in Figure 2, with corresponding pancreatographic images in Figures 3–7.

Indications for Endoscopic Retrograde Pancreatography The clinical value of ERP lies in the diagnosis of various pancreas disorders along with their appropriate therapy. The emergence of less invasive modalities that provide detailed views of the pancreatic duct, such as magnetic resonance cholangiopancreatography (MRCP) and endoscopic ultrasound (EUS), have largely replaced ERP as a diagnostic test in most clinical settings (Figures 8 –10). Currently, the main role of ERP is to image the pancreatic duct as a prelude to pancreatic endotherapy. There are 5 general indications for ERP. (1) ERP as a prelude to pancreatic endotherapy in the setting of acute pancreatitis, chronic pancreatitis, and sphincter of Oddi dysfunction. Appropriate images of the pancreatic ductal system are necessary before treatment of pancreatic ductal strictures, pancreatic ductal stones, duct disruption and communicating pseudocysts, etc.5 Treatment of pancreatic sphincter disease with a pancreatic sphincterotomy has become more common. Pancreatography is helpful before performing this maneuver and for placing a prophylactic pancreatic stent. (2) ERP for defining the cause of idiopathic acute pancreatitis.6 Potential pancreatographic findings in idiopathic acute pancreatitis include pancreatic sphincter of Oddi dysfunction (usually diagnosed by sphincter of Oddi manometry), pancreas divisum, anomalous pancreaticobiliary union and other congenital variants, and neoplasms (eg, intraductal papillary mucinous neoplasm [IPMN], Figure 11). Pancreas divisum might be missed on MRCP, even when secretin is used.7 Therefore, ERCP continues to be the gold standard for diagnosing pan-

Figure 2. Variants of pancreatic ductal anatomy. (a) The main pancreatic duct drains through the major papilla. The accessory duct is patent and drains through minor papilla. (b) Same as (a), except that the minor papilla is not patent, and the accessory duct and branches terminate near the duodenal wall. (c) The main pancreatic duct extends caudally in an ansa contour. (d) Complete pancreas divisum with a small ventral duct draining through the major papilla. There is a large dorsal duct draining through the minor papilla. (e) Incomplete pancreas divisum with a small branch connecting the ventral and the dorsal pancreatic ducts. (f) A variant of pancreas divisum in which the entire pancreatic ductal system drains through the minor papilla. There is no pancreatic duct connecting to the major papilla. (g) The same as (f) except that the dorsal pancreatic duct extends caudally in a “half-loop” configuration. (h) Complete pancreas divisum with saccular dilation of the terminal part of the dorsal pancreatic duct (Santorinicele). (i) Reversed pancreas divisum with the accessory ductal system draining a small portion of the pancreatic parenchyma through the minor papilla. There is no connection between the main and accessory ducts. Reproduced with permission from the Indiana University School of Medicine’s Office of Visual Media.

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and avoid prolonged major papilla attempts at obtaining a pancreatogram. Presence of large pancreatic stones might require another procedure (eg, extracorporeal shock wave lithotripsy) before the ERCP to facilitate the subsequent stone removal. A scout film should be obtained before cannulation and contrast injection. This image would help to avoid confusion as to what abnormalities existed before contrast injection. The presence of intraductal pancreatic stones will often be obscured by contrast. Before cannulation, the catheter should be flushed with contrast to avoid introduction of any air into the pancreatic duct. Pneumopancreatograms can lead to false interpretation of the radiographic findings, eg, falsely suggest an obstruction of the pancreatic duct. Prophylactic antibiotics should be administered in patients undergoing evaluation and/or therapy of pancreatic cystic lesions and fluid collections.

Figure 3. Normal pancreatogram. (A) Normal main pancreatic duct up to the tail of the pancreas. (B) A magnified view of the normal main pancreatic duct in the head and the body of the pancreas in the same patient. Note the finely tapered side branches.

diagnosing more advanced stages of the disease because less invasive radiologic (computed tomography [CT], magnetic resonance imaging [MRI]/MRCP) and endoscopic (EUS) imaging tests are equally sensitive. (5) Visualization of at least a portion of the main pancreatic duct before placement of a prophylactic pancreatic duct stent. The endoscopic literature is now replete with evidence that shows that placement of pancreatic stents reduces the incidence of post-ERCP pancreatitis in highrisk settings.11

Pre-Procedure Planning Personally reviewing prior radiographic pancreatic imaging before beginning the ERCP is often of value. Accurate determination of pancreatic pathology, eg, the location of a stricture, a leak (Figure 12), a pseudocyst, presence and size of stones (Figures 13, 14), or anatomic ductal variation (Figure 15) can allow better planning of the procedure. For example, in a patient with acute recurrent pancreatitis, recognition of pancreas divisum on MRCP and/or EUS (Figure 16) would allow the endoscopist to be focused on minor papilla cannulation

Figure 4. Complete pancreas divisum. (A) Contrast injection through the minor papilla shows the entire dorsal duct with no communication with the ventral duct. (B) Injection through the major papilla opacifies a small ventral duct with its terminal branches.

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Figure 5. Incomplete pancreas divisum. Contrast injection through the major papilla fills the dorsal pancreatic duct through the small communicating branch (arrow). There is a cystic dilation of the terminal part of the dorsal pancreatic duct (Santorinicele, arrowhead).

Major Papilla Cannulation Major papilla pancreatic cannulation techniques are similar to those used for biliary cannulation, with exceptions that the smaller size, the duct tortuosity, and the multiple side branches make deep wire passage more difficult in some cases.12 Although both a sphincterotome and a standard cannula are widely used for biliary cannulation, with a sphincterotome probably performing better,13 we prefer to use a standard tapered tip cannula for initial attempt at pancreatic duct cannulation. With the duodenoscope facing the papilla en face, the pancreatic orifice will almost always arise from the 1 to 4 o’clock position on the os. In contrast to the upward direction of cannulation of the bile duct, ventral pancreatic duct cannulation is best achieved with the catheter oriented in a more “straight on direction” (Figure 17), with the scope positioned toward the left wall of the duodenum at or slightly above the papilla (best performed when the scope is in the short position).

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Figure 7. Ansa pancreatica. A guidewire has been advanced around the loop to the neck of the pancreas.

Occasionally, positioning the scope just below the papilla will be helpful for cannulation, particularly when the pancreatic duct takes a more upward direction from the ampulla. If deep cannulation is not easily achieved, impacting the tip of the catheter at the orifice and gently injecting contrast might visualize the pancreatic duct. Deep cannulation can then be achieved by manipulating the catheter by using fluoroscopic guidance with or without a guidewire. Guidewire cannulation of the pancreatic duct is recommended when therapy is planned or standard techniques fail. Smaller-diameter guidewires (.018 and .025 inches) that are hydrophilic and/or flexible tipped are recommended to navigate ductal turns and avoid side-branch entry. If cannulation of the pancreatic duct is still difficult, then intravenous secretin (0.2 ␮g/kg; SecreFlo, Repligen Corporation, Waltham, MA) might facilitate pancreatic duct cannulation as a result of widening of the orifice during the increase in juice flow and relaxation of the sphincter of Oddi.14 This technique is more useful at the minor papilla or after a biliary sphincterotomy is done. In a case of difficult pancreatic duct cannulation with repeated inadvertent entrance into the bile duct, a wire could be left in the bile duct to improve the chance of subsequent pancreatic cannulation. More aggressive techniques such as precut pancreatic sphincterotomy are rarely necessary. After a biliary sphincterotomy, the pancreatic orifice is most commonly found at the 5 o’clock position. Many endoscopists use ultra-tapered (5F-4F-3F) tip catheters for cannulation of the pancreatic duct. If a sphincterotome is used for pancreatic duct cannulation, then less upward angulation should be applied to successfully cannulate the pancreatic duct.

Minor Papilla Cannulation

Figure 6. Annular pancreas and pancreas divisum. Contrast injection through the major papilla shows a short ventral duct with an annular branch encircling the descending duodenum.

The technical aspects of minor papilla cannulation are outlined in detail in our previous review.15 As noted above, although cannulation of the minor papilla can be performed to confirm the diagnosis of pancreas divisum, noninvasive and less invasive imaging studies such as thin-slice coronal CT scan, secretin-stimulated MRCP, and EUS can provide the diagnosis with reasonably good accuracy.16 –18 Most commonly, minor

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papilla cannulation is undertaken for therapeutic indications. In addition, in non-divisum patients, minor papilla cannulation can allow for therapeutic maneuvers in the pancreatic duct when cannulation of the ventral pancreatic duct is unsuccessful, or tortuous ductal anatomy (such as in an ansa pancreatica ductal configuration) prevents deep guidewire passage. In these settings, the minor papilla must be patent and the accessory duct in continuity with the main pancreatic duct. The minor papilla is usually located superior and anterior to the major papilla, which corresponds to the right upper quadrant portion of the visual field when using the side-viewing duodenoscope. It

Figure 8. (A) Radial endosonography from the duodenum shows normal pancreatic duct in the head of the pancreas. (B) Radial endosonography from the stomach shows normal pancreatic duct in the body of the pancreas. PD, pancreatic duct; CBD, common bile duct; PV, portal vein; HA, hepatic artery; CONF, confluence; BOP, body of the pancreas; SV, splenic vein; LRV, left renal vein. (C) Normal pancreatic duct as shown by secretin-enhanced MRCP. Figure 9. (A) MRCP shows multiple side-branch cysts involving the whole pancreas, suggestive of a multifocal side-branch IPMN. (B) EUS image in the same patient shows one of the cysts with mural nodule, suspicious for malignancy. SV, splenic vein; BOP, body of pancreas.

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The orifice of the minor papilla is then “penetrated” by the ultra-tapered catheter, and contrast is injected. Once deep cannulation is achieved, it is often advantageous to withdraw the scope into the short position (along the lesser curve of the stomach) because of improved mechanical advantage, patient comfort, and more “natural position” of the pancreatic duct. In patients with an inconspicuous minor papilla or minor papilla orifice, intravenous administration of secretin can facilitate identification of the orifice.14 It is important to appreciate that when secretin is given, it might be difficult to force contrast media retrograde to the tail because of vigorous anterograde juice flow, and using such force might precipitate pancreatitis. Occasionally, however, it is still difficult to find the minor papilla or its orifice, even with secretin stimulation (as might occur in patients with chronic pancreatitis and low pancreatic juice flow). In this scenario, spraying dilute methylene blue dye over the minor papilla might help to identify the orifice.19 Rarely will a precut sphincterotomy of the minor papilla be required. In experienced centers, minor papilla cannulation can be achieved in approximately 95% of cases. Dorsal pancreatograms are generally identical to standard major papilla pancreatograms, except that the duct-duodenal junction is more perpendicular. An exception to this rule is the saccular terminal dorsal duct dilation (Santorinicele) seen in about 15% of patients.20

Endoscopic Ultrasound–Assisted Pancreatography Even the most experienced endoscopists sometimes encounter patients in whom repeated attempts at cannulation of the pancreatic duct have failed. In these cases, EUS with a linear array echoendoscope can be of assistance. During this procedure, a 19-gauge or 22-gauge needle is used to enter the pancreatic duct via the transgastric route under real-time EUS.

Figure 10. Secretin-enhanced MRCP (A) in a 60-year-old man with a history of idiopathic acute pancreatitis shows a stricture in the neckbody of the pancreas (arrow), with upstream dilation of the pancreatic duct. MRI in the same patient (B) shows a mass (arrow) in the neckbody of the pancreas. These data obviate the need for ERCP.

might be as close as 10 mm from the major papilla or “attached” to the major papilla, but most commonly it is about 2–3 cm cephalad to the major papilla. Placing the duodenoscope in the long position along the greater curve of the stomach often facilitates cannulation (Figure 18). Because the orifice of the minor papilla might be extremely small, a diagnostic pancreatogram is usually obtained, with a highly tapered 5F catheter and a 23-gauge or 25-gauge blunt needle tip protruding 1–2 mm beyond the catheter tip. The needle tip should be gently inserted into the orifice to avoid tissue trauma and blurring of landmarks. Because this catheter does not accept a guidewire, therapeutic maneuvers are not possible with this catheter. When therapy is planned and deep cannulation is required, we prefer to use an ultra-tapered (5F-4F-3F) tip catheter with a 0.018-inch guidewire. To minimize the trauma to the minor papilla, the tip of the guidewire is extended 2–3 mm beyond the tip of the cannula and is passed under visual and fluoroscopic guidance deeply into the dorsal pancreatic duct.

Figure 11. Main duct IPMN. Note multiple filling defects (arrows) representing mucus in the dilated main pancreatic duct.

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Figure 12. (A) Secretin-enhanced MRCP shows extravasation of the contrast from the pancreatic duct in the tail of the pancreas (arrow). Initial contrast injection into the pancreatic duct during ERP shows a stricture in the body-tail of the pancreas (B, arrows), with no extravasation seen in the tail (C). Having known the results of MRCP, we injected more contrast in the tail, with resultant demonstration of the pancreatic duct leak (D, arrow).

Contrast is then injected into the pancreatic duct to obtain a pancreatogram21 (Figure 19). If pancreatic endotherapy is indicated, a guidewire might be placed into the pancreatic duct across the papilla and into the duodenum under EUS and fluoroscopic guidance, which facilitates subsequent retrograde cannulation of the pancreas after exchange to the standard duodenoscope by using the rendezvous technique.22–26 EUS-guided injection of a mixture of contrast and methylene blue into the pancreatic duct might help to identify the minor and major papilla orifices. After exchange for a sideviewing duodenoscope, blue dye can be seen exiting the papilla orifice, facilitating subsequent cannulation.27 We also have used this technique to find the pancreatic orifice at the major papilla in patients with stenosis of previous endoscopic sphincterotomy or surgical sphincteroplasty.28 EUSguided techniques are also useful in patients who have un-

dergone a Whipple procedure in which identification of the pancreas orifice is usually quite difficult, particularly when it is stenosed.

Choice of Contrast Because the incidence of post-ERCP pancreatitis was not reduced with use of low osmolality contrast media (LOCM),29,30 we use standard high osmolality contrast media, which are considerably less expensive. The incidence of adverse reactions to iodine-containing contrast media administered at the time of ERCP, even in patients considered to be at high risk, is exceedingly low.31 In patients considered at high risk for contrast media reactions (ie, those with a prior anaphylactoid reaction to intravascular contrast media), premedication and/or substitution of LOCM might be considered.32

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Figure 14. A large pancreatic stone with acoustic shadow in the pancreatic duct at the genu of the pancreas as seen by EUS. PD, pancreatic duct; CONF, portal confluence.

We prefer to use full strength contrast in the pancreatic duct, so that side-branch filling is easily seen and the duct is not overfilled. This allows us to obtain high quality pancreatographic images by using only a small amount of contrast, which might reduce the likelihood of postprocedure pancreatitis.

Pancreatic Duct Contrast Injection and Obtaining Fluoroscopic Images The catheter tip should be placed just inside the duct. Forceful injection within the papilla itself might cause a submucosal dissection and further conceal a portion of the pancreatic duct. Insertion that is too deep might enter a side branch and cause acinarization or rupture of a branch duct. Contrast media should be injected slowly, so that optimal ductal views can be obtained during fluoroscopy and small filling defects are most likely to be seen. Because the risk of post-ERCP pancreatitis in-

Figure 13. (A) Abdominal CT scan in an elderly woman with steatorrhea and weight loss shows a large calcified intraductal stone (arrowhead), with severe dilation of the upstream main pancreatic duct (arrows). (B) A dilated main pancreatic duct with prominent side branches in the head of the pancreas. A large radiopaque stone (arrow) prevents opacification of the upstream duct. (C) Partial visualization of the main pancreatic duct (arrows) upstream to the stone (arrowhead) is achieved. Note that with forceful contrast injection, the pancreatic duct stone moved to the junction of the neck and body of the pancreas.

Figure 15. A loop configuration of the otherwise normal main pancreatic duct as shown by secretin-enhanced MRCP.

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Optimal fluoroscopic images are obtained with a 180-degree rotatable C arm. The ability to rotate the fluoroscopy unit allows separation of the pancreatic duct and the bile ducts and the imaging of areas of the duct obscured by the shaft of the endoscope. It is also important to position the endoscope off the pancreatic ductal system for complete duct visualization. The pancreatic duct tends to have its normal configuration when the scope is in the short position and is often distorted in

Figure 16. Complete pancreas divisum as demonstrated by secretinenhanced MRCP (A). Note the dorsal pancreatic duct (arrows), which is not connected to the ventral pancreatic duct (arrowhead). (B) EUS shows a pancreatic duct (red arrow) that does not cross the border (black arrow) between the ventral (Ventr) and dorsal (Dors) portions of the pancreas, raising suspicion of pancreas divisum.

creases with increasing number of contrast injections into the pancreatic duct and extent of pancreatic duct opacification,33–35 the smallest amount of contrast required to achieve adequate fluoroscopic images should be used. It is our practice to not fill the duct at the tail and upstream body if noninvasive imaging shows no pathology in this region. Acinarization, defined as fluoroscopically observed focal or diffuse pancreatic parenchymal blush of contrast (Figure 20) occurring when the volume of contrast dye injected into the main pancreatic duct (or side branch) exceeds the ductal capacity, has been reported to double the risk of post-ERCP pancreatitis.34 On the other hand, underfilling can lead to misinterpretation. Thus, an obstructing lesion in the pancreatic body or tail might be missed if the pancreatic duct is incompletely filled.

Figure 17. Technique of pancreatic duct cannulation. (A) The duodenoscope facing the papilla en face, with the catheter oriented in straight on direction. (B) Pancreatic orifice location on the major papilla surface. Reproduced with permission from The Indiana University School of Medicine’s Office of Visual Media.

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Figure 18. Duodenoscope in a long position for minor papilla cannulation in a patient with complete pancreas divisum. Injection of contrast through the minor papilla fills the entire dorsal duct. There is no communication with the ventral duct.

the long position. The pancreatic tail might not fill completely in the prone position. Completion of the pancreatogram can be achieved by rotating the patient to the left lateral decubitus position, thereby avoiding the risk associated with further injection of contrast.36

Pancreas Divisum Diagnosis Repeated failed attempts at ventral duct cannulation and a prominent minor papilla37 might be initial clues to pancreas divisum anatomy. The short ventral duct in a case of pancreas divisum can simulate an obstructed main pancreatic duct. Conversely, pathologic obstruction of the main duct close to the papilla that might be seen in pancreatic cancer or rarely in chronic pancreatitis might mimic pancreas divisum (pseudodivisum, Figure 21). Attention to detail should minimize diagnostic confusion. The ventral duct in pancreas divisum is smaller than normal but arborizes normally; an obstructed duct usually comes to an abrupt termination and often

Figure 19. EUS-assisted pancreatography. Contrast is injected into the pancreatic duct via the transgastric route under EUS and fluoroscopic guidance in patient after failed retrograde cannulation of the main pancreatic duct.

Figure 20. (A) Acinarization of the dorsal pancreas in the upper head in a patient with pancreas cancer (contrast injection via the minor papilla). Note that a biliary stent has been placed. (B) Obstruction of the ventral pancreatic duct with mild acinarization in the same patient (contrast injection via the major papilla).

demonstrates a prestenotic dilation when further contrast is injected. If there is any diagnostic doubt, the minor papilla should be cannulated and injected to confirm the presence of pancreas divisum and to differentiate it from ventral duct obstruction.36

Figure 21. Cutoff of the main pancreatic duct in the head of the pancreas in a patient with carcinoma in the head of the pancreas (pseudodivisum). Note abrupt termination of the main duct in the pancreatic head.

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Table 1. Classification of Pancreatograms in Chronic Pancreatitis (Cambridge Criteria)

Terminology

MPD

Abnormal MPD branches

Normal Equivocal Mild CP Moderate CP Severe CP

Normal Normal Normal Abnormal Abnormal

None ⬍3 3 or more ⬎3 ⬎3

Additional features

None One or more: large cavity obstruction, filling defects, severe dilatation, or irregularity

CP, chronic pancreatitis; MPD, main pancreatic duct.

Focal dilatation at the termination of the dorsal duct, or Santorinicele, is observed in about 15% of patients with pancreas divisum (Figure 5). It is believed to result from a combination of obstruction and weakness of the terminal duct wall

Figure 23. Moderate chronic pancreatitis. Note the dilated and irregular main pancreatic duct with abnormal side branches.

and seems to be more common in patients with the minor papilla located within a diverticulum. Some authors have proposed that Santorinicele represents a sign of increased intraductal pressure and possibly a useful predictor of a good outcome after endoscopic drainage.20

Chronic Pancreatitis Diagnosis There are several classification systems used to define the presence and characterize the severity of chronic pancreatitis. The Cambridge classification system, which is most commonly used, classifies chronic pancreatitis according to morphologic changes of the pancreatic ducts38 (Table 1, Figures 22–25). One of the earliest findings of chronic pancreatitis is an abnormal branch of the main pancreatic duct. Unfortunately, interobserver variability is greatest in early stage disease, and ERP is believed to be a relatively insensitive method for the diagnosis of early stage chronic pancreatitis. Moreover, sufficient amount of contrast medium must be injected to image the side branches of the pancreatic ducts when mild changes of pancreatitis are sought, which can raise the risk of

Figure 22. (A) Mild chronic pancreatitis with normal-appearing main pancreatic duct (arrow). The side branches are dilated and irregular (arrowheads). (B) Secretin-enhanced MRCP in the same patient shows identical findings.

Figure 24. Stricture in the main pancreatic duct in a patient with severe chronic pancreatitis (arrow).

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Figure 25. Multiple stones in the main pancreatic duct in a patient with severe chronic pancreatitis.

post-ERCP pancreatitis.35,39 – 41 The intraductal secretin test, which measures pancreatic secretory flow rate and bicarbonate concentration after secretin stimulation, might improve the sensitivity of ERP for diagnosing early chronic pancreatitis.10 Some authors have suggested that changes mimicking chronic pancreatitis (eg, pancreatic duct dilation) occur in the pancreas with increasing age. This possibility should be taken into account in assessing pancreatograms in elderly patients.42,43

Conclusion ERP continues to be an invaluable tool for diagnosis and treatment of a variety of pancreatic diseases. Achieving deep pancreatic cannulation can be challenging at times for experts and novices alike. Good quality radiography is absolutely essential for diagnosis, assistance in therapy, and to limit complications. It is hoped that this review will help ERCP physicians obtain safe and accurate pancreatograms. References 1. McCune WS, Shorb PE, Moscovitz H. Endoscopic cannulation of the ampulla of Vater: a preliminary report. Ann Surg 1968;167: 752–756. 2. Mergener K, Kozarek RA. Therapeutic pancreatic endoscopy. Endoscopy 2005;37:201–207. 3. England RE, Newcomer MK, Leung JW, et al. Case report: annular pancreas divisum: a report of two cases and review of the literature. Br J Radiol 1995;68:324 –328. 4. Lehman GA, O’Connor KW. Coexistence of annular pancreas and pancreas divisum: ERCP diagnosis. Gastrointest Endosc 1985; 31:25–28. 5. Lehman GA. Role of ERCP and other endoscopic modalities in chronic pancreatitis. Gastrointest Endosc 2002;56:S237– S240. 6. Kozarek R. Role of ERCP in acute pancreatitis. Gastrointest Endosc 2002;56:S231–S236. 7. Carnes ML, Romagnuolo J, Cotton PB. Miss rate of pancreas divisum by magnetic resonance cholangiopancreatography in clinical practice. Pancreas 2008;37:151–153. 8. De Bellis M, Sherman S, Fogel EL, et al. Tissue sampling at ERCP in suspected malignant biliary strictures (part 2). Gastrointest Endosc 2002;56:720 –730.

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Reprint requests Address requests for reprints to: Olga Barkay, MD, Indiana University Hospital, 550 North University Boulevard, Suite 4100, Indianapolis, Indiana 46202. e-mail: [email protected]; fax: (317) 274-3710. Conflicts of interest The authors disclose no conflicts.