DOI: 10.1148/rg.275065163
RadioGraphics 2007;27:1389-1400
© RSNA, 2007
Disconnection of the Pancreatic Duct: An Important But Overlooked Complication of Severe Acute Pancreatitis1
Kumaresan Sandrasegaran, MD,
Mark Tann, MD,
S. Gregory Jennings, MD,
Dean D. Maglinte, MD,
Sanjit D. Peter, MD,
Stuart Sherman, MD, and
Thomas J. Howard, MD
1 From the Departments of Radiology (K.S., M.T., S.G.J., D.D.M.), Surgery (S.D.P., T.J.H.), and Medicine (S.S.), Indiana University School of Medicine, 550 N University Blvd, Suite UH 0279, Indianapolis, IN 46202. Recipient of a Certificate of Merit award for an education exhibit at the 2005 RSNA Annual Meeting. Received September 5, 2006; revision requested October 30 and received December 18; accepted December 19. K.S. receives research support from Koninklijke Philips Electronics NV, Cleveland, Ohio; D.D.M. is a consultant for Cook, Bloomington, Ind, and E-Z-Em, Westburg, NY; S.S. is a consultant for Repligen, Waltham, Mass; all other authors have no financial relationships to disclose.
Address correspondence to K.S. (e-mail: ksandras{at}iupui.edu).
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Abstract
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In patients with severe acute pancreatitis, the percentage of necrosis of pancreatic glandular parenchyma is an important predictor of prognosis. However, little attention has been paid to necrosis of ductal epithelium, which may result in disconnection of the main pancreatic duct. In pancreatic duct disconnection, a viable segment of the pancreatic body or tail is isolated from the gastrointestinal tract; the result is a persistent end fistula, that is, an uncontrolled leak of pancreatic secretions into peripancreatic spaces without communication to the gastrointestinal tract. The authors present their experience with clinical and radiologic follow-up of 85 patients with necrotic pancreatitis who either did (n = 46) or did not (n = 39) have pancreatic duct disconnection at surgery. Confident preoperative diagnosis of a disconnected duct requires both imaging tests (computed tomography or magnetic resonance imaging) and pancreatography. However, not all peripancreatic collections signify ductal disconnection, and imaging has poor accuracy in differentiation between pancreatic and peripancreatic necrosis. Early recognition of disconnected pancreatic duct obviates unnecessary and potentially harmful drainage procedures.
© RSNA, 2007
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Introduction
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The imaging method of choice for assessment of acute pancreatitis is computed tomography (CT). Contrast material–enhanced CT is used to evaluate the cause of the pancreatitis and the presence of pancreatic necrosis. This modality is also used to detect local complications, such as acute fluid collections and vascular damage. The spectrum of CT findings associated with acute pancreatitis and its complications has been extensively documented (1,2). Magnetic resonance (MR) imaging and MR cholangiopancreatography are alternatives to CT, particularly for patients in whom intravenous iodinated contrast material is contraindicated (3).
Pancreatic necrosis occurs in 20%–30% of cases of acute pancreatitis (4). The initial mortality of severe pancreatitis is related to organ failure and pancreatic necrosis. The radiologic grading of acute pancreatitis, proposed by Balthazar (5), takes into account the degree of necrosis that is seen at CT (Table 1). Clinical classification systems such as the Atlanta classification (7) (Table 2) also include pancreatic necrosis in categorization of severity. In the Atlanta classification, pancreatitis is deemed severe in the presence of pancreatic necrosis, organ failure (renal or pulmonary), shock, gastrointestinal bleeding, at least three Ranson criteria (Table 3) (8), or at least eight APACHE II points (Table 4) (9).
The Atlanta and Balthazar classifications concentrate on the severity of glandular necrosis and provide important prognostic information. However, in a subset of patients with necrotic pancreatitis, the brunt of the disease is on the ductal epithelium and not glandular tissue. Such patients survive the initial period but continue to have inflammatory collections for several weeks. They are at increased risk of complications such as infection if appropriate therapy is not instituted early (10).
Ductal necrosis can result in the entity called disconnection of the main pancreatic duct. This term was coined in 1996 (11) and has been previously described in the surgical, gastrointestinal, and radiologic literature (12–16). Disconnected pancreatic duct is an anatomic situation where there is a lack of main pancreatic ductal continuity between viable secreting pancreatic tissue and the gastrointestinal tract (Fig 1). The isolated viable pancreatic segment continues to have an exocrine output that is not drained into bowel. The resultant fistula and inflammatory collections are persistent and are unlikely to resolve with conservative drainage measures (12,16–19). The prevalence of pancreatic ductal disconnection is not known.
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Figure 1a. Anatomy of disconnected pancreatic duct. (a) Necrosis of the entire width of the pancreatic neck, body, or proximal tail (single arrow) leads to a viable upstream segment (arrowhead) that no longer drains into the duodenum. Note that the angle the fluid collection makes with the main pancreatic duct ( ) is close to 90°. The length of the necrosis (double arrow) should be at least 2 cm. If the condition is untreated, the exocrine secretions of the disconnected segment continue to feed the fluid collection for a prolonged period until acinar atrophy of the disconnected segment occurs. (b) Intraoperative photograph (original magnification, x2) of an 83-year-old woman with necrotizing pancreatitis shows lack of a connection between the pancreatic tail (white arrowhead) and the proximal body (single arrow) due to necrosis of the intervening segment (double arrow). A pediatric feeding tube (black arrowhead) was inserted into the pancreatic duct in the tail.
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Figure 1b. Anatomy of disconnected pancreatic duct. (a) Necrosis of the entire width of the pancreatic neck, body, or proximal tail (single arrow) leads to a viable upstream segment (arrowhead) that no longer drains into the duodenum. Note that the angle the fluid collection makes with the main pancreatic duct () is close to 90°. The length of the necrosis (double arrow) should be at least 2 cm. If the condition is untreated, the exocrine secretions of the disconnected segment continue to feed the fluid collection for a prolonged period until acinar atrophy of the disconnected segment occurs. (b) Intraoperative photograph (original magnification, x2) of an 83-year-old woman with necrotizing pancreatitis shows lack of a connection between the pancreatic tail (white arrowhead) and the proximal body (single arrow) due to necrosis of the intervening segment (double arrow). A pediatric feeding tube (black arrowhead) was inserted into the pancreatic duct in the tail.
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In this article, we discuss diagnosis of disconnected pancreatic duct in the setting of severe acute pancreatitis. This diagnosis is often overlooked with imaging tests. We discuss how this diagnosis affects treatment options. Our experience is derived from clinical and radiologic follow-up of 85 patients with necrotic pancreatitis who either did (n = 46) or did not (n = 39) have ductal disconnection at surgery.
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Diagnosis of Disconnected Pancreatic Duct
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To confidently diagnose disconnected pancreatic duct, it is necessary to demonstrate all of the following features: (a) necrosis of at least 2 cm of pancreas, (b) viable pancreatic tissue upstream (ie, toward the pancreatic tail) from the site of necrosis, and (c) extravasation of contrast material injected into the main pancreatic duct at pancreatography.
Note that not all patients with pancreatic necrosis have pancreatic duct disconnection. The CT or MR imaging hallmarks of ductal disconnection are a large intrapancreatic collection or necrosis (ie, nonenhancement) of a section of the pancreatic head, neck, or body, combined with a viable segment of the distal body or tail (Figs 2–4). The duct in the pancreatic tail segment may or may not be dilated. When visible, the main pancreatic duct enters the collection at an angle of approximately 90° (Fig 4a). In all cases of disconnected pancreatic duct that were proved surgically in our series, there was longitudinal necrosis of at least 2 cm of pancreatic glandular tissue. Necrosis over a shorter segment may result in healing of the duct, although usually with stricture formation (20).
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Figure 2a. Acute disconnection of the pancreatic duct in a 62-year-old man with prior episodes of alcoholic pancreatitis. (a) Axial CT image shows a 7-cm-diameter fluid collection occupying the pancreatic head and neck (arrow). The collection is confined within the capsule of the gland with no enhancing tissue in the neck. The duct in the viable pancreatic body is dilated (arrowhead). (b) Image from endoscopic retrograde cholangiopancreatography (ERCP) shows extravasation of injected contrast material (arrows). The main pancreatic duct is abruptly cut off (white arrowhead). Note the embolization coils (black arrowhead) in a pseudoaneurysm of the inferior pancreaticoduodenal artery. Disconnected pancreatic duct was diagnosed, and the patient underwent median segment pancreaticojejunostomy.
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Figure 2b. Acute disconnection of the pancreatic duct in a 62-year-old man with prior episodes of alcoholic pancreatitis. (a) Axial CT image shows a 7-cm-diameter fluid collection occupying the pancreatic head and neck (arrow). The collection is confined within the capsule of the gland with no enhancing tissue in the neck. The duct in the viable pancreatic body is dilated (arrowhead). (b) Image from endoscopic retrograde cholangiopancreatography (ERCP) shows extravasation of injected contrast material (arrows). The main pancreatic duct is abruptly cut off (white arrowhead). Note the embolization coils (black arrowhead) in a pseudoaneurysm of the inferior pancreaticoduodenal artery. Disconnected pancreatic duct was diagnosed, and the patient underwent median segment pancreaticojejunostomy.
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Figure 3a. Disconnected pancreatic duct in an 18-year-old woman with gallstone pancreatitis. (a) Axial CT image shows that the entire pancreatic body and the proximal tail are necrosed (arrow). A viable upstream segment of the pancreatic tail (arrowhead) is noted. (b) ERCP image shows extravasation of contrast material (arrow) from the region of the pancreatic neck. A wire (arrowhead) could not be passed beyond the extravasation site into the upstream duct of the pancreatic body and tail.
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Figure 3b. Disconnected pancreatic duct in an 18-year-old woman with gallstone pancreatitis. (a) Axial CT image shows that the entire pancreatic body and the proximal tail are necrosed (arrow). A viable upstream segment of the pancreatic tail (arrowhead) is noted. (b) ERCP image shows extravasation of contrast material (arrow) from the region of the pancreatic neck. A wire (arrowhead) could not be passed beyond the extravasation site into the upstream duct of the pancreatic body and tail.
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Figure 4a. Disconnected pancreatic duct in a 67-year-old man with alcohol-induced pancreatitis who experienced ductal disconnection during the third acute episode. Coronal T2-weighted turbo spin-echo MR image (a) and secretin-enhanced MR cholangiopancreatogram (b) show a complex 8-cm-diameter fluid collection (arrow) replacing the neck and superior head of the pancreas. The main pancreatic duct (arrowhead) enters the collection. Disconnected pancreatic duct was proved at surgery.
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Figure 4b. Disconnected pancreatic duct in a 67-year-old man with alcohol-induced pancreatitis who experienced ductal disconnection during the third acute episode. Coronal T2-weighted turbo spin-echo MR image (a) and secretin-enhanced MR cholangiopancreatogram (b) show a complex 8-cm-diameter fluid collection (arrow) replacing the neck and superior head of the pancreas. The main pancreatic duct (arrowhead) enters the collection. Disconnected pancreatic duct was proved at surgery.
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To confirm disconnection of the main pancreatic duct, it is necessary to show extravasation of ductal contents. Traditionally, ERCP has been used for this purpose (Figs 2, 3). Ductal disconnection may also be demonstrated with endoscopic ultrasonographically guided duct injection or surgical pancreatography. More recently, MR cholangiopancreatography enhanced with secretin (SecreFlo; Repligen, Waltham, Mass) has been suggested to be of value in assessing ductal continuity and pancreatic fistulas (Fig 5) (21,22). The technique of secretin-enhanced MR cholangiopancreatography has been described elsewhere (23).
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Figure 5a. Pancreatic duct stenosis without ductal disconnection after acute pancreatitis. (a) MR cholangiopancreatogram obtained without secretin shows apparent discontinuity of the main pancreatic duct at the level of the pancreatic neck (curved arrow) with an adjacent fluid collection (arrowhead). Note the acute angle between the pancreatic duct and the fluid collection. There is diffuse ascites (straight arrow). (b) MR cholangiopancreatogram obtained 7 minutes after administration of secretin shows that the main pancreatic duct is stenosed at the neck (curved arrow) and not disconnected. The adjacent fluid collection (arrowhead) appears slightly brighter than on the presecretin image; this finding is suggestive of extravasation of pancreatic juice after increased exocrine output in response to secretin. Note the diffuse ascites (straight arrow). (c) ERCP image shows the ductal stenosis (arrowhead) and the absence of disconnection. The fluid collection is filled with injected contrast material (arrow), a finding indicative of disruption of a side branch without disconnection of the main pancreatic duct. The upstream pancreatic duct is mildly distended. The patient was treated with a stent and did not need surgery.
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Figure 5b. Pancreatic duct stenosis without ductal disconnection after acute pancreatitis. (a) MR cholangiopancreatogram obtained without secretin shows apparent discontinuity of the main pancreatic duct at the level of the pancreatic neck (curved arrow) with an adjacent fluid collection (arrowhead). Note the acute angle between the pancreatic duct and the fluid collection. There is diffuse ascites (straight arrow). (b) MR cholangiopancreatogram obtained 7 minutes after administration of secretin shows that the main pancreatic duct is stenosed at the neck (curved arrow) and not disconnected. The adjacent fluid collection (arrowhead) appears slightly brighter than on the presecretin image; this finding is suggestive of extravasation of pancreatic juice after increased exocrine output in response to secretin. Note the diffuse ascites (straight arrow). (c) ERCP image shows the ductal stenosis (arrowhead) and the absence of disconnection. The fluid collection is filled with injected contrast material (arrow), a finding indicative of disruption of a side branch without disconnection of the main pancreatic duct. The upstream pancreatic duct is mildly distended. The patient was treated with a stent and did not need surgery.
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Figure 5c. Pancreatic duct stenosis without ductal disconnection after acute pancreatitis. (a) MR cholangiopancreatogram obtained without secretin shows apparent discontinuity of the main pancreatic duct at the level of the pancreatic neck (curved arrow) with an adjacent fluid collection (arrowhead). Note the acute angle between the pancreatic duct and the fluid collection. There is diffuse ascites (straight arrow). (b) MR cholangiopancreatogram obtained 7 minutes after administration of secretin shows that the main pancreatic duct is stenosed at the neck (curved arrow) and not disconnected. The adjacent fluid collection (arrowhead) appears slightly brighter than on the presecretin image; this finding is suggestive of extravasation of pancreatic juice after increased exocrine output in response to secretin. Note the diffuse ascites (straight arrow). (c) ERCP image shows the ductal stenosis (arrowhead) and the absence of disconnection. The fluid collection is filled with injected contrast material (arrow), a finding indicative of disruption of a side branch without disconnection of the main pancreatic duct. The upstream pancreatic duct is mildly distended. The patient was treated with a stent and did not need surgery.
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We do not consider subacute pancreatitis, even if clinically severe, to be an absolute contraindication to use of intravenous secretin. However, if there is a recent history (<4 weeks) of acute pancreatitis, we use this agent only in inpatients whose clinical and laboratory status can be closely monitored. Our concern is that by increasing exocrine output, secretin may increase the degree of inflammation in and around the pancreas. We have performed secretin-enhanced MR cholangiopancreatography in 54 patients with acute pancreatitis and have not seen biochemical or clinical worsening of pancreatitis. Five of these patients experienced transient abdominal pain that did not require specific therapy, and the MR imaging examination had to be terminated in three cases owing to the abdominal pain. We know of two patients with confirmed pancreatitis after the use of secretin, but these patients had pancreas divisum and no history of recent acute pancreatitis.
The sensitivity of secretin-enhanced MR cholangiopancreatography for showing extravasation at the site of pancreatic duct disconnection is lower than that of ERCP (23). It is probable that the ductal pressure reached with manual injection of contrast material during ERCP cannot be achieved with increased exocrine output in response to secretin (Fig 6); in any case, such a response is usually suboptimal in patients with pancreatitis. In addition, the presence of an adjacent fluid collection or ascites makes it difficult to perceive small ductal leaks. Thus, confident preoperative diagnosis of a disconnected duct requires both imaging tests (CT or MR imaging) and pancreatography.
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Figure 6a. Absence of ductal disconnection in a 48-year-old man with a history of alcoholic pancreatitis. (a) MR cholangiopancreatogram obtained without secretin shows an 8-cm-diameter fluid collection (arrow) adjacent to the pancreatic body. Some fluid is noted in the second part of the duodenum (arrowhead). Axial T2-weighted images showed an acute angle between the main pancreatic duct and the fluid collection. (b) MR cholangiopancreatogram obtained 7 minutes after intravenous administration of secretin shows more fluid in the duodenum (arrowhead) owing to increased exocrine pancreatic secretions in response to secretin. The fluid collection (arrow) is not noticeably larger or brighter, and there is no evidence of fluid leakage from the pancreatic duct. (c) ERCP image shows extravasation of contrast material (straight arrow) from the main pancreatic duct. There is filling of the moderately dilated upstream pancreatic duct (curved arrow), a finding that indicates absence of ductal disconnection. A wire (arrowhead) was passed into the fluid collection.
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Figure 6b. Absence of ductal disconnection in a 48-year-old man with a history of alcoholic pancreatitis. (a) MR cholangiopancreatogram obtained without secretin shows an 8-cm-diameter fluid collection (arrow) adjacent to the pancreatic body. Some fluid is noted in the second part of the duodenum (arrowhead). Axial T2-weighted images showed an acute angle between the main pancreatic duct and the fluid collection. (b) MR cholangiopancreatogram obtained 7 minutes after intravenous administration of secretin shows more fluid in the duodenum (arrowhead) owing to increased exocrine pancreatic secretions in response to secretin. The fluid collection (arrow) is not noticeably larger or brighter, and there is no evidence of fluid leakage from the pancreatic duct. (c) ERCP image shows extravasation of contrast material (straight arrow) from the main pancreatic duct. There is filling of the moderately dilated upstream pancreatic duct (curved arrow), a finding that indicates absence of ductal disconnection. A wire (arrowhead) was passed into the fluid collection.
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Figure 6c. Absence of ductal disconnection in a 48-year-old man with a history of alcoholic pancreatitis. (a) MR cholangiopancreatogram obtained without secretin shows an 8-cm-diameter fluid collection (arrow) adjacent to the pancreatic body. Some fluid is noted in the second part of the duodenum (arrowhead). Axial T2-weighted images showed an acute angle between the main pancreatic duct and the fluid collection. (b) MR cholangiopancreatogram obtained 7 minutes after intravenous administration of secretin shows more fluid in the duodenum (arrowhead) owing to increased exocrine pancreatic secretions in response to secretin. The fluid collection (arrow) is not noticeably larger or brighter, and there is no evidence of fluid leakage from the pancreatic duct. (c) ERCP image shows extravasation of contrast material (straight arrow) from the main pancreatic duct. There is filling of the moderately dilated upstream pancreatic duct (curved arrow), a finding that indicates absence of ductal disconnection. A wire (arrowhead) was passed into the fluid collection.
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Diagnostic Pitfalls
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Not All Peripancreatic Collections Signify Ductal Disconnection
Intra- or peripancreatic fluid collections per se do not signify ductal disconnection. Acute collections may result from focal disruptions of the main pancreatic duct or its side branches (Fig 5) and may compress pancreatic tissue to such an extent that a segment of the gland appears to be necrosed. For this reason, it is important to look for a thin bridge of viable glandular tissue that is compressed inferiorly or posteriorly by the fluid collection. Identification of such a bridge of tissue prevents misdiagnosis of pancreatic duct disconnection (Figs 7, 8). In this respect, coronal or sagittal reformations may be helpful. When a fluid collection compresses the gland, the pancreatic duct is usually displaced and makes an oblique angle (not a right angle) with the wall of the collection (Fig 9).
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Figure 7a. Absence of ductal disconnection in a 39-year-old woman with alcohol- and pancreas divisum–related pancreatitis. (a) Axial CT image shows a 4-cm-diameter fluid collection (arrow) in the pancreatic neck. The main pancreatic duct (arrowhead) appears to enter the collection. (b) Axial CT image obtained inferior to a shows a bridge of viable tissue in the pancreatic neck (arrow). Note the stent in the dorsal (Santorini) duct. (c) ERCP image obtained with cannulation of the minor papilla shows stenosis of the main duct (curved arrow) in the pancreatic neck. Extravasation of contrast material into the fluid collection is seen (straight arrow). The duct in the pancreatic body is also opacified (arrowhead), a finding that indicates absence of ductal disconnection in the pancreatic neck. Owing to concern about provoking acute pancreatitis, filling of the duct in the pancreatic tail was not attempted.
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Figure 7b. Absence of ductal disconnection in a 39-year-old woman with alcohol- and pancreas divisum–related pancreatitis. (a) Axial CT image shows a 4-cm-diameter fluid collection (arrow) in the pancreatic neck. The main pancreatic duct (arrowhead) appears to enter the collection. (b) Axial CT image obtained inferior to a shows a bridge of viable tissue in the pancreatic neck (arrow). Note the stent in the dorsal (Santorini) duct. (c) ERCP image obtained with cannulation of the minor papilla shows stenosis of the main duct (curved arrow) in the pancreatic neck. Extravasation of contrast material into the fluid collection is seen (straight arrow). The duct in the pancreatic body is also opacified (arrowhead), a finding that indicates absence of ductal disconnection in the pancreatic neck. Owing to concern about provoking acute pancreatitis, filling of the duct in the pancreatic tail was not attempted.
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Figure 7c. Absence of ductal disconnection in a 39-year-old woman with alcohol- and pancreas divisum–related pancreatitis. (a) Axial CT image shows a 4-cm-diameter fluid collection (arrow) in the pancreatic neck. The main pancreatic duct (arrowhead) appears to enter the collection. (b) Axial CT image obtained inferior to a shows a bridge of viable tissue in the pancreatic neck (arrow). Note the stent in the dorsal (Santorini) duct. (c) ERCP image obtained with cannulation of the minor papilla shows stenosis of the main duct (curved arrow) in the pancreatic neck. Extravasation of contrast material into the fluid collection is seen (straight arrow). The duct in the pancreatic body is also opacified (arrowhead), a finding that indicates absence of ductal disconnection in the pancreatic neck. Owing to concern about provoking acute pancreatitis, filling of the duct in the pancreatic tail was not attempted.
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Figure 8a. Absence of ductal disconnection in a 33-year-old woman with idiopathic pancreatitis. (a, b) Axial CT images (a obtained at a lower level than b) show a large fluid collection (curved arrow) occupying most of the pancreatic neck. A thin rim of compressed tissue (straight arrow) is seen posterior to the collection. A pancreatic stent (arrowhead) is present. (c) Axial CT image obtained at a more superior level shows a mildly distended main duct in the pancreatic body and tail (arrows). The pancreatic stent (arrowhead) traverses the pancreatic head and neck, and there is no disconnection of the main pancreatic duct. At follow-up CT 3 months later, the large fluid collection had resolved spontaneously. A small fluid collection is incidentally noted adjacent to the pancreatic tail.
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Figure 8b. Absence of ductal disconnection in a 33-year-old woman with idiopathic pancreatitis. (a, b) Axial CT images (a obtained at a lower level than b) show a large fluid collection (curved arrow) occupying most of the pancreatic neck. A thin rim of compressed tissue (straight arrow) is seen posterior to the collection. A pancreatic stent (arrowhead) is present. (c) Axial CT image obtained at a more superior level shows a mildly distended main duct in the pancreatic body and tail (arrows). The pancreatic stent (arrowhead) traverses the pancreatic head and neck, and there is no disconnection of the main pancreatic duct. At follow-up CT 3 months later, the large fluid collection had resolved spontaneously. A small fluid collection is incidentally noted adjacent to the pancreatic tail.
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Figure 8c. Absence of ductal disconnection in a 33-year-old woman with idiopathic pancreatitis. (a, b) Axial CT images (a obtained at a lower level than b) show a large fluid collection (curved arrow) occupying most of the pancreatic neck. A thin rim of compressed tissue (straight arrow) is seen posterior to the collection. A pancreatic stent (arrowhead) is present. (c) Axial CT image obtained at a more superior level shows a mildly distended main duct in the pancreatic body and tail (arrows). The pancreatic stent (arrowhead) traverses the pancreatic head and neck, and there is no disconnection of the main pancreatic duct. At follow-up CT 3 months later, the large fluid collection had resolved spontaneously. A small fluid collection is incidentally noted adjacent to the pancreatic tail.
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Figure 9a. Large fluid collection compressing the pancreas and no ductal disconnection. (a) The pancreatic duct is displaced by a fluid collection and makes an acute angle () with the wall of the collection. (b) Absence of ductal disconnection in a 57-year-old man with a single prior episode of pancreatitis. Axial CT image shows a cystic lesion (arrow) in the posterior neck and body of the pancreas; the lesion displaces the main pancreatic duct (arrowhead) anteriorly. The duct makes an acute angle with the body of the cystic mass. Because of the possibility of a malignant cystic mass, surgery was performed. Surgical biopsy demonstrated that the lesion was a pseudocyst. Cystojejunostomy was performed.
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Figure 9b. Large fluid collection compressing the pancreas and no ductal disconnection. (a) The pancreatic duct is displaced by a fluid collection and makes an acute angle () with the wall of the collection. (b) Absence of ductal disconnection in a 57-year-old man with a single prior episode of pancreatitis. Axial CT image shows a cystic lesion (arrow) in the posterior neck and body of the pancreas; the lesion displaces the main pancreatic duct (arrowhead) anteriorly. The duct makes an acute angle with the body of the cystic mass. Because of the possibility of a malignant cystic mass, surgery was performed. Surgical biopsy demonstrated that the lesion was a pseudocyst. Cystojejunostomy was performed.
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Poor Accuracy of Imaging in Differentiation between Pancreatic and Peripancreatic Necrosis
Full-thickness glandular necrosis associated with entry of the duct at a right angle into the necrosed tissue allows correct prediction of pancreatic duct disconnection in most patients. However, despite careful attention to the described pitfalls, in some patients prediction of pancreatic duct disconnection with CT may be incorrect (Fig 10). Imaging tests do not allow reliable differentiation between peripancreatic fat necrosis, pancreatic parenchymal necrosis, and pancreatic ductal necrosis. In our experience, MR imaging is not superior to CT in differentiating between these types of necrosis. Therefore, to reliably diagnose disconnection of the pancreatic duct, it is necessary to show extravasation of injected contrast material from the main pancreatic duct without filling of the upstream duct.
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Figure 10a. Absence of ductal disconnection in a 52-year-old man with alcoholic pancreatitis. (a) Axial CT image obtained during the acute phase of pancreatitis shows a fluid collection (straight arrow) that apparently replaces the pancreatic body. The pancreatic tail (curved arrow) enhances normally. A prospective diagnosis of disconnected pancreatic duct was made. In retrospect, there are possible wisps of poorly enhancing periductal tissue (arrowheads) in the pancreatic body. Necrosectomy and débridement were performed. The necrosis was predominantly of periglandular fat. The patient was found to not have ductal disconnection at surgery. (b) Axial CT image obtained 3 months later shows a normally enhancing pancreatic body without a residual fluid collection. The patient also underwent coil embolization of a pseudoaneurysm of the superior pancreaticoduodenal artery (arrow). Note the right renal cyst and the open abdominal wound.
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Figure 10b. Absence of ductal disconnection in a 52-year-old man with alcoholic pancreatitis. (a) Axial CT image obtained during the acute phase of pancreatitis shows a fluid collection (straight arrow) that apparently replaces the pancreatic body. The pancreatic tail (curved arrow) enhances normally. A prospective diagnosis of disconnected pancreatic duct was made. In retrospect, there are possible wisps of poorly enhancing periductal tissue (arrowheads) in the pancreatic body. Necrosectomy and débridement were performed. The necrosis was predominantly of periglandular fat. The patient was found to not have ductal disconnection at surgery. (b) Axial CT image obtained 3 months later shows a normally enhancing pancreatic body without a residual fluid collection. The patient also underwent coil embolization of a pseudoaneurysm of the superior pancreaticoduodenal artery (arrow). Note the right renal cyst and the open abdominal wound.
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Treatment of Disconnected Pancreatic Duct
Most peripancreatic collections following acute pancreatitis are treated conservatively or with guided drainage (4,16,24–26). In the absence of infection, surgery is not usually contemplated. However, if there is a viable segment of gland that continually feeds the collection with its exocrine juices, a chronic end fistula is created (Fig 11).
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Figure 11a. Disconnected pancreatic duct in a 54-year-old woman with pancreatitis thought to have been induced by hyperlipidemia. (a) Axial CT image obtained during the subacute phase of pancreatitis shows a large fluid collection (curved arrow) occupying the entire pancreatic body. A viable disconnected tail segment is noted (straight arrow). Multiple gastrocystic stents were placed (arrowhead). Gas bubbles are present in the fluid collection due to a connection with the gastric lumen. There were no clinical features of sepsis. (b) On an axial CT image obtained 5 months later, the fluid collection (straight arrow) is smaller and there is resolution of ascites. However, persistence of the collection, despite the presence of multiple gastrocystic stents (arrowhead) and percutaneously placed drains (curved arrows), was consistent with a disconnected pancreatic duct. Distal pancreatectomy was performed.
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Figure 11b. Disconnected pancreatic duct in a 54-year-old woman with pancreatitis thought to have been induced by hyperlipidemia. (a) Axial CT image obtained during the subacute phase of pancreatitis shows a large fluid collection (curved arrow) occupying the entire pancreatic body. A viable disconnected tail segment is noted (straight arrow). Multiple gastrocystic stents were placed (arrowhead). Gas bubbles are present in the fluid collection due to a connection with the gastric lumen. There were no clinical features of sepsis. (b) On an axial CT image obtained 5 months later, the fluid collection (straight arrow) is smaller and there is resolution of ascites. However, persistence of the collection, despite the presence of multiple gastrocystic stents (arrowhead) and percutaneously placed drains (curved arrows), was consistent with a disconnected pancreatic duct. Distal pancreatectomy was performed.
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Identification of this anatomic situation is important. In a recent study, the imaging findings in 47 consecutive patients with pancreatic necrosis who underwent surgical débridement were blindly reviewed (27). The results were classified as showing pancreatic duct disconnection (n = 22) or no disconnected duct (n = 25) by using the criteria discussed earlier. There was no difference in age, sex, cause of pancreatitis, Balthazar CT score, or percentage of glandular necrosis between the groups. Postoperative pancreatic fistulas occurred in 74% of patients with evidence of ductal disconnection compared to only 46% of patients with no evidence of disconnection. Furthermore, the rates of spontaneous closure of the fistula were 18% and 64% in those with and those without evidence of ductal disconnection, respectively. These observations suggest that imaging identification of pancreatic duct disconnection predicts the likelihood of persistent pancreatic fistulas.
The difficulty of closing pancreatic fistulas in patients with pancreatic duct disconnection has also been emphasized in the endoscopy literature. Endoscopic stent placement in the pancreatic duct has been used as a therapeutic option to close pancreatic fistulas in patients after acute pancreatitis (13). However, only six of 23 patients (26%) with complete disconnection of the pancreatic duct responded to endoscopic stent placement at the disconnection site (28). These findings suggest that patients with acute necrotic pancreatitis in whom a disconnected pancreatic duct is identified at imaging are at increased risk of persistent pancreatic fistula, which in most cases will require surgery.
Surgical therapy may involve removal of the viable disconnected pancreatic segment or creation of a pancreaticojejunostomy to drain this segment. The choice of surgery depends on the age of the patient, the presence of continued retroperitoneal inflammation, the volume of the disconnected segment, and the exocrine and endocrine pancreatic function (29). In patients in whom the disconnected distal portion of the gland is thought to substantially contribute to pancreatic function, median segment pancreaticojejunostomy is the preferred surgical option (Fig 12) (12). Distal pancreatectomy with or without splenectomy may be performed if the disconnected segment is small.
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Conclusions
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In this article, we have discussed the cross-sectional imaging and ERCP findings of disconnected pancreatic duct. This is an important finding for the radiologist to recognize in the setting of necrotic pancreatitis. Early diagnosis of this condition enables more definitive therapy to be instituted and obviates unnecessary drainage procedures.
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Footnotes
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Abbreviations: APACHE II = Acute Physiology and Chronic Health Evaluation II, ERCP = endoscopic retrograde cholangiopancreatography
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References
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Abstract
Introduction
