Endoscopic Ultrasound in Pancreatic Duct Anomalies

Abstract

Embryological development of the pancreas is a complex phenomenon and, therefore, it can have multiple developmental aberrations. Fortunately, the majority of these pancreatic ductal anomalies are asymptomatic with no clinical relevance and are incidentally detected during diagnostic cross-sectional imaging or endoscopic retrograde cholangiopancreatography (ERCP) or autopsy. Occasionally, pancreatic duct anomalies can result in symptoms like abdominal pain or recurrent pancreatitis. Also, an accurate pre-operative diagnosis of ductal anomalies can prevent inadvertent duct injury during surgery. Conventionally, ERCP had been used for an accurate diagnosis of pancreatic duct anomalies. However, because it is invasive and associated with a risk of pancreatitis, it has been replaced with magnetic resonance cholangiopancreatography (MRCP). MRCP has demonstrated high sensitivity and specificity for the diagnosis of ductal anomalies, which can be further improved with the use of secretin-enhanced MRCP. Endoscopic ultrasound (EUS) is a new diagnostic and interventional tool in the armamentarium of endoscopists and has demonstrated promising results in the detection of pancreatic duct variations and anomalies. Along with the visualization of the course and configuration of the pancreatic duct, EUS can also visualize changes in the pancreatic parenchyma, thereby helping with an early diagnosis of any co-existent pancreatic disease. Absence of the stack sign and crossed duct sign are important EUS features to diagnose pancreas divisum. EUS can also help with the diagnosis of other congenital ductal anomalies like annular pancreas, ansa pancreatica, and anomalous pancreaticobiliary union, although the published experience is limited.

Keywords: annular pancreas; endosonography; magnetic resonance cholangiopancreatography; pancreas divisum.

Figure 1

Radial EUS showing both ventral pancreatic duct and common bile duct stacked together. This finding rules out pancreas divisum.

Figure 2

Radial EUS: Portal vein and common bile duct are seen but ventral pancreatic duct is not seen. This finding suggests diagnosis of pancreas divisum.

Figure 3

Stack sign on linear EUS.

Figure 4

Pancreatic duct dipping towards major papilla excludes pancreas divisum.

Figure 5

Annular pancreas: CECT showing pancreatic tissue encircling descending duodenum.

Figure 6

Linear EUS shows pancreatic tissue lateral to the duodenum.