You are in: eMedicine Specialties > Radiology > GASTROINTESTINAL Pancreas DivisumArticle Last Updated: May 3, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 10
  Author: Majid A Khan, MD, Consulting Neuroradiologist, Department of Diagnostic Radiology, GV(Sonny) Montgomery VA Medical Center Majid A Khan, MD, is a member of the following medical societies: American College of Radiology and American Society of Neuroradiology Coauthor(s): Israh Akhtar, MD, Staff Physician, Department of Pathology, Nassau University Medical Center, State University of New York at Stony Brook; David I Weltman, MD, Consulting Staff, S & D Medical, LLP; Director, Department of Radiology, Southside Hospital Editors: Glenn Krinsky, MD, Chief of Abdominal Imaging Section, Associate Professor, Department of Radiology, New York University School of Medicine; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; Paul M Silverman, MD, Professor, Chief of Body Imaging, Chair in Diagnostic Imaging, Department of Radiology, University of Texas MD Anderson Cancer Center; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; John Karani, MBBS, FRCR, Consulting Staff, Department of Radiology, King's College Hospital, London Author and Editor Disclosure Synonyms and related keywords: pancreatic divisum, duct of Santorini, minor papilla stenosis, duct of Wirsung INTRODUCTIONSection 2 of 10
  BackgroundPancreas divisum, the most common congenital variant of the pancreatic anatomy, occurs when the ductal systems of the ventral and dorsal pancreatic ducts fail to fuse. As a result of nonunion of the ducts, a major portion of pancreatic exocrine secretions enter the duodenum via the dorsal duct and minor papilla. Generally, it has been accepted that a relative obstruction to pancreatic exocrine secretory flow through the minor duct and minor papilla can result in pancreatitis in a small number of patients with pancreas divisum (with stenotic minor papilla). Incomplete or partial divisum is defined as the communication of the dorsal and ventral ducts via a tiny branch. PathophysiologyMost people with anomalous pancreatic ductal systems are asymptomatic and completely unaffected by the condition; however, a significant number of patients present with recurrent attacks of acute pancreatitis. A relative obstruction to the flow of pancreatic fluid at the level of an inadequately patent or stenosed minor papilla has been hypothesized to result in an increase in intraductal pressure with consequent pancreatitis. FrequencyInternationalPancreas divisum is observed in 6% of normal persons at autopsy. The frequency with which pancreas divisum has been diagnosed during a patient’s lifetime has increased with newer diagnostic modalities. Mortality/MorbidityAn incidence of pancreas divisum as high as 10-20% has been reported in some series in patients with acute recurrent pancreatitis. The actual incidence of divisum and minor papilla stenosis is not known, but it is certainly significantly less than that of pancreas divisum alone. RaceNo racial predominance exists, although the anomaly has been noted more frequently in whites. SexThe male-to-female ratio is 1:1. AgeAge ranges from 7 months to 98 years, with a median age at diagnosis of 57 years. AnatomyThe pancreas is formed during the embryologic stage from distinct ventral and dorsal buds, which arise from the duodenal diverticulum. The ventral duct undergoes rotation and fuses with the dorsal duct by the seventh week of intrauterine life. In 1642, Wirsung demonstrated the main pancreatic duct, and in 1775, Santorini accurately described the ductal anatomy and demonstrated the accessory pancreatic duct. Typically, the main pancreatic duct is derived from both embryologic parts of the pancreas; the dorsal pancreas provides the main duct in the tail and body of the gland, and the ventral pancreas provides the main duct in the head of the gland. The accessory duct (called the duct of Santorini) is the remaining portion of the duct in the dorsal pancreas and may drain through an accessory papilla more proximally in the duodenal loop. In pancreas divisum, the ventral and dorsal pancreatic ducts fail to fuse in utero, resulting in drainage of the bulk of pancreatic fluid (80-95%) via the duct of Santorini through the relatively small minor papilla. Clinical DetailsThe symptom complex of patients with pancreas divisum and minor papilla stenosis includes abdominal pain of varying intensity, with epigastric pain radiating to the back and pain brought on by alcohol intake and worsened by eating fatty foods. Patients usually present with nausea, vomiting, weight loss, diarrhea, and jaundice (which can be both obstructive and nonobstructive). Many patients are treated for gastritis, irritable bowel syndrome, or other conditions before a more definitive investigation for a pancreatic abnormality. Patients usually present with an increased serum amylase level, lipase level, bilirubin level, white blood cell count, or urinary amylase-to-urinary creatinine ratio. Preferred ExaminationTake a methodical approach to the patient with recurrent abdominal pain and pancreas divisum. The presence of clear-cut pancreatitis in association with this anomaly on presentation makes it easier to determine whether the pancreas is the site of origin of the abdominal pain. In patients with divisum who do not demonstrate clinical pancreatitis, determine the existence of accessory papilla stenosis. Some patients may demonstrate focal dilatation of the pancreatic duct at the minor ampulla (termed santorinicele). Endoscopic retrograde cholangiopancreatography (ERCP) is the test of choice for making a diagnosis of pancreas divisum. Occasionally, this anomaly can be depicted with computed tomography (CT), but CT has a low sensitivity and requires thin slices. Magnetic resonance pancreatography (with or without secretin) may replace ERCP for diagnostic purposes in the future. Limitations of TechniquesERCP is expensive and invasive, with a reported complication rate of 5%. The use of secretin increases the cost of MRI examination because of the cost of the drug and the additional imaging time. DIFFERENTIALSSection 3 of 10
Choledochal Cyst Pancreas, Adenocarcinoma Pancreatitis, Acute Pancreatitis, Chronic Other Problems to Be Considered:Annular pancreas RADIOGRAPHSection 4 of 10
FindingsERCP is the diagnostic test of choice for the diagnosis of pancreas divisum (see Image 1, see Image 2); however, magnetic resonance pancreatography (with or without secretin) will likely replace this invasive test for diagnostic purposes in the future. Criteria for the diagnosis of pancreas divisum on ERCP are as follows (see Images 10-11):
ERCP is also used for therapeutic intervention in patents with pancreas divisum (see Intervention). Degree of ConfidenceEndoscopic cannulation of the accessory papilla is considered technically difficult. Because of the small size of the accessory papilla, it is difficult to recognize and localize. The overall success rate of cannulation depends on the experience of the endoscopic team, technical improvements in endoscopes and catheters, and the interest in precisely documenting ductal morphology. CT SCANSection 5 of 10
FindingsCT is frequently used to evaluate patients with chronic pancreatitis or chronic abdominal pain. Images are analyzed for glandular size, contour, and focal alteration in attenuation. Single or multislice helical CT with 1-3 mm collimation, overlapping reconstructions, and the use of water as a negative contrast agent provide for high-quality images amenable to three-dimensional (3D) reformations. While demonstration of ductal anatomy by CT is more difficult than demonstration of gross glandular architecture, use of meticulous technique, minimum-intensity projection algorithms, and curved reformations can often show the pancreatic duct throughout its entire course. CT criterion for the diagnosis of pancreas divisum is visualization of the nonunion of the dorsal and ventral ducts directly joining the common bile duct (see Images 3-9). Although it is possible to confuse a patent accessory duct of Santorini with divisum, in the normal pancreas, a vertical segment of the main pancreatic duct caudal to the accessory duct is usually seen on its way to the ampulla of Vater. In divisum, this segment of the duct is not present. In addition, an accessory duct should not be confused with a ventral duct, since the accessory duct does not join the bile duct. Additional evidence of pancreas divisum on dynamic thin-section CT is the visualization of a fat-attenuation cleft separating the pancreatic head from the pancreatic body. This cleft runs obliquely through the section and acts as a boundary between the 2 distinct pancreatic moieties visible at the same craniocaudal level. Fatty infiltration of the dorsal portion of the gland can also be observed with a normal ventral portion. False Positives/NegativesComplete pancreatic ductal anatomy and the presence of separate dorsal and ventral pancreatic moieties are seen only in a minority of patients using conventional CT. Zeman et al1 were able to definitively identify separate dorsal and ventral ducts in only 5 of 12 patients with known pancreas divisum. Thin-section multislice helical CT may be more accurate, but no studies using this technique have been reported. MRISection 6 of 10
FindingsMagnetic resonance cholangiopancreatography (MRCP) is a noninvasive imaging modality that accurately and simultaneously depicts morphologic abnormalities of the biliary and the pancreatic ducts and parenchymal structures. Bret et al2 were able to identify pancreas divisum in 6 of 114 MRCP examinations using a body coil and 19 of 154 MRCP examinations using a torso coil. Exogenous administration of secretin stimulates the secretion of fluids and bicarbonates by the exocrine pancreas, with a consequent increase in the volume of fluid inside the pancreatic ducts. This increase in fluid content is used to improve the visualization of pancreatic ductal anatomy on MRCP. Nonfusion of ventral and dorsal pancreatic ducts in pancreas divisum can be recognized more readily after secretin-stimulated MRCP. The amount of fluid secreted into the duodenum can also be quantified to assess the degree of pancreatic exocrine reserve in patients with chronic pancreatitis related to pancreatic divisum. Manfredi et al3 identified pancreas divisum in 7% of patients (6 of 84) by MRCP before secretin administration and in 14% of patients (12 of 84) following secretin administration. Recent development of half-Fourier pulse sequences and phased-array surface coils enables the acquisition of high-quality images during breath holding, with a high signal-to-noise ratio. Parameters that can be assessed before and after administration of secretin in MRCP include the following:
Abnormalities indicative of chronic pancreatitis secondary to minor papilla stenosis in patients with pancreas divisum can be seen more frequently following secretin administration. Degree of ConfidenceIn the series by Bret et al,2 ERCP was performed following MRCP in fewer than half of the patients, but the sensitivity and specificity of MRCP for pancreas divisum was 100% in this group. ULTRASOUNDSection 7 of 10
FindingsSecretin-stimulated ultrasound ( Degree of ConfidenceSecretin-stimulated US is 78% sensitive in detecting surgically proven pancreatic duct stenosis. INTERVENTIONSection 8 of 10
ERCP is used for therapeutic intervention in patents with pancreas divisum. Endoscopic intervention has yielded encouraging results, although no consensus has been reached about which approach is the best (surgery vs ERCP). Various endoscopic approaches used for the treatment of pancreas divisum with acute recurrent pancreatitis include endoscopic sphincterotomy of the minor ampulla, with or without sphincterotomy of the major ampulla; ductal balloon dilatation; and pancreatic duct stent placement (see Image 12). Despite a relatively small number of patients and a near absence of controlled randomized trials, the patients most likely to benefit from endoscopic therapy, as with a surgical approach, appear to be those with well-documented acute recurrent pancreatitis rather than those with pain or chronic pancreatitis alone. MULTIMEDIASection 9 of 10
REFERENCESSection 10 of 10
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