In order for digestion to occur, bile and pancreatic enzymes are secreted through the papilla of Vater (major duodenal papilla) and into the second or descending part of the duodenum. Both the biliary tree and the pancreatic duct share a common channel at Vater's ampulla (the hepatopancreatic ampulla). Consequently, it's not surprising that diseases of either system can affect the other, particularly when the main pancreatic duct and the common bile duct are involved. The following will discuss clinical scenarios involving the pancreaticobiliary system, such as common bile duct stones, strictures, and acute and chronic pancreatitis that physicians are likely to encounter in practice.
The cornerstone of managing these disorders is endoscopic retrograde cholangiopancreatography (ERCP), a procedure where at duodenoscopy, a special side-viewing video endoscope cannulates the Vater's ampulla so that a cholangiogram and pancreatogram can be obtained. The next step is the appropriate therapeutic procedure to deal with the specific problem at hand.
do common bile duct stones present?
Common bile duct stones are perhaps one of the most frequently seen gastrointestinal (GI) problems. A stone in the common duct will produce biliary pain. The pain is typically felt in the upper abdomen/right quadrant and radiates to the back between the scapulae. At times, it may also present as severe chest pain and could be confused with cardiac pain. Symptoms often occur in patients with previously undiagnosed gallstone disease. However, the pain may arise even after a cholecystectomy, and it's not unusual for patients to say that it feels very much like a previous gallbladder attack, despite having had their gallbladder removed.
The crucial difference between a gallbladder attack and a common bile duct stone episode is that the stone in the common bile duct generates signs and symptoms of a common duct obstruction. On the other hand, acute cholecystitis, resulting from a stone obstructing the cystic duct, produces gallbladder tenderness, both clinically and via ultrasound, with features of gallbladder wall thickening, in addition to fluid collection around the gallbladder. Typically, there are no signs or symptoms of common bile duct obstruction in acute cholecystitis.
Pain may be associated with jaundice, though not always. In a patient who is not jaundiced, the liver enzymes aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase are elevated. This obstruction can further be complicated by a biliary tract infection (i.e. acute cholangitis) or pancreatic inflammation (i.e. acute pancreatitis) because they share a common channel. In this situation, patients are often in severe pain and require opioid analgesics in the emergency department. Some patients with acute cholangitis, particularly the elderly, may have no pain at all and the major clinical presentation can be fever, septic shock, confusion or heart failure.
does an initial evaluation begin?
If common bile duct stones are suspected, order a complete blood count (CBC). If the white blood cell count (WBC) is elevated, consider a diagnosis of acute cholangitis. Other blood work should include liver enzymes AST, ALT and alkaline phosphatase, which are invariably elevated. If the pancreatic enzyme, lipase/amylase, is elevated (typically in the 1,000s), consider a diagnosis of acute pancreatitis.
An ultrasound examination may demonstrate gallstones, a dilated biliary tree (because of a stone obstructing the duct) and a swollen pancreas in the case of pancreatitis. Keep in mind that in the majority of patients, the actual stone in the common bile duct doesn't show up on ultrasound. Consequently, it's important to rely on other indicators to make a diagnosis.
are they managed?
Pain relief is the first, and foremost therapeutic step and usually requires opioid-type analgesics. For acute cholangitis, broad-spectrum antibiotics are invariably effective. A minority of cases don't respond to antibiotics and require urgent endoscopic intervention to drain the obstructed biliary tree ERCP, sphincterotomy and removal of the stones with basket or balloon sweep extraction. Percutaneous biliary drainage is an option used infrequently especially when endoscopic therapy isn't feasible.
Most cases of acute biliary pancreatitis resolve on their own because of spontaneous passage of the stone. In these cases, management consists of bowel rest, intravenous fluids and analgesics. In a small number of individuals (about 10%), however, extraction of the stone by endoscopic means is urgently required. These patients often have evidence of severe pancreatitis and persistent biliary obstruction with cholangitis. In such instances, urgent ERCP intervention is essential for a favourable outcome. Once these complications are dealt with, the next step is laparoscopic cholecystectomy.
In many cases, the patient will ask about permanent damage to the pancreas. Simply reassure these individuals that the organ will return to its normal functioning state.
On the other hand, severe acute necrotizing pancreatitis although uncommon can have devastating consequences. These patients require intensive care and can experience complications from pancreatic and systemic infections, and sometimes death. On presentation, they're so ill that the challenge is to treat the severe pancreatitis and not the offending stone.
do common bile duct strictures present?
Obstructive jaundice is the most common initial presentation with common bile duct strictures, and some patients may complain of intense itching. Unlike a stone in the bile duct, pain is uncommon. Occasionally, the liver enzymes will show an obstructive pattern (i.e. high bilirubin, alkaline phosphatase, gamma glutamyl transpeptidase and minimal AST/ALT elevation). Itching may be the dominant symptom, which is related to elevated bile salts and not to the degree of jaundice.
Any individual presenting with anorexia or sudden weight loss should alert you to the possibility of a malignancy. Carcinoma of the head of pancreas is the most frequent cause of a malignant stricture. Other causes include cholangicarcinoma and ampullary carcinoma. Benign strictures are usually caused by chronic pancreatitis, common duct injury (i.e. post cholecystectomy), and other rare conditions such as primary sclerosing cholangitis and Mirizzi's syndrome (benign obstruction of the bile duct). In malignant strictures, the prognosis is quite poor, with the worst being pancreatic malignancy. With surgical excision, ampullary carcinoma carries the best five-year survival rate.
When a patient presents with a bile duct stricture, jaundice may be the only physical finding. The liver may also be slightly enlarged and, if the site of the obstruction is at the lower end of the common duct near the pancreatic head, the gallbladder will also be distended and may be detected by palpation.
investigations are next?
Blood work requires a CBC, international normalized ratio (INR) and liver enzymes. An ultrasound examination of the abdomen should follow these investigations, which, in the presence of a mechanical obstruction, will show a dilated biliary tree and, in some cases, gallbladder dilatation. The exact cause of the obstruction, for example, a pancreatic mass, may be seen on ultrasound, but can easily be missed.
Once ultrasound confirms an obstructive process, the next steps are to assess the type and location of the stricture and relieve the jaundice with stent therapy (the latter two are achieved by ERCP, and in the rare case of a failed ERCP, percutaneous transhepatic cholangiography). The patient must also be evaluated to determine resectability of the underlying problem. Ideally, a computed tomography (CT) scan or magnetic resonance imaging (MRI) can help in sorting out this process.
In my practice, the usual approach would be a CT scan, followed by a diagnostic and therapeutic ERCP, though it may not always be possible to follow this sequence.
about malignant vs benign strictures?
In patients with pancreatic carcinoma, for example, the stricture is usually identified at the lower end of the common bile duct and an endobiliary stent is put in place to relieve jaundice. Depending on various factors age, comorbidity and CT scan features (probability of a resection) a surgical consultation should be obtained. If suitable for surgery, a malignancy in this area calls for Whipple's operation, which involves a pancreaticoduodenectomy (the head of the pancreas is removed along with the duodenal loop), a partial gastrectomy, gastrojejunostomy, a biliary enteric anastomosis and a pancreaticoenteric anastomosis. Surgery is extensive and morbidity and mortality is lower in expert hands.
Benign strictures are less common and are most often seen in known cases of chronic pancreatitis (about 10-15% of such cases may present with obstructive jaundice). They're also rarely seen post-cholecystectomy (about two months after surgery, an ischemic stricture may develop), and when there's surgical injury to the common duct followed by repair. A stricture may also develop from primary sclerosing cholangitis (chronic inflammatory/fibrosing process involving both the intra and extrahepatic biliary tree). The most common associated disease is ulcerative colitis.
Management of these strictures involves identifying the type and site of the stricture, followed by stenting to relieve jaundice. Depending on the clinical scenario, other options such as ongoing stent therapy or balloon dilatation of the stricture, or surgical bypass may be considered.
is chronic pancreatitis?
The chronic form of pancreatitis differs greatly from the acute form. They are, in fact, two distinct diseases. As the name implies, chronic pancreatitis is a long-standing disease process characterized by chronic inflammation and fibrosis, which may ultimately lead to parenchymal fibrosis, ductal stenosis/stones, and acinar and islet cell destruction. Alcohol abuse is the most frequent cause of chronic pancreatitis, which manifests after many decades.
Pain is the most typical symptom. Post-prandial epigastric pain, often radiating to the back and relieved by analgesics, but not by acid-suppressing drugs, should suggest the possibility of chronic pancreatitis. To better define the diagnosis, try to obtain a history of alcohol abuse and perform other investigations.
Blood work is often not helpful in making a diagnosis, and pancreatic lipase/amylase enzymes are usually normal. An ultrasound may show a bulky pancreas and perhaps pancreatic ductal dilatation. A CT scan, however, is quite reliable in depicting a bulky pancreas (although in advanced cases, the pancreas may look small and atrophied), pancreatic calcification and ductal dilatation resulting from a stricture or stone within the duct. Chronic pancreatitis is best handled by a gastroenterologist with a special interest in pancreaticobiliary disorders.
In the latter part of the disease course, pancreatic insufficiency develops. Exocrine insufficiency presents as weight loss due to malabsorption. At this stage, the pancreas' functioning is usually wiped out by 90%, leaving the digestive enzymes (lipase, protease, amylase, etc.) unable to be produced in reasonable amounts. As a result, fat and protein malabsorption occur. At a later stage, other manifestations such as diabetes and loss of islet cells may result.
is it managed?
The most important first step is to get patients to abstain from alcohol. Over time many, but not all, will benefit from this approach. As with common bile duct stones, offer pain relief with analgesics, typically codeine preparations. When looking at the big picture, the disease will burn itself out in about 10-15 years, resulting in diminished pain, but onset of pancreatic insufficiency.
An important mechanism to consider is an obstructed pancreatic duct due to a stricture or stone. The resulting ductal dilatation/distention, which causes pain, is often referred to as a "surgical duct," mainly because surgery can decompress the distended duct. Similar results may be obtained from endoscopic decompression through ERCP. The benefits aren't consistently good, particularly because of confounding factors such as analgesic addiction, depression and chronic pain syndrome. In some respects, the less invasive endoscopic therapy may predict the results of surgery, though many patients who undergo the endoscopic/surgical procedure will require other supportive measures such as ongoing (and hopefully diminishing) analgesic use and antidepressants. This can be much more easily accomplished through good communication with the primary care physician and a pain clinic.
In certain instances, the ducts aren't distended, yet the patient complains of pancreatic pain. These ducts are often referred to as "medical ducts" or "small duct disease." In such cases, the pain is probably neural, arising from the extensive fibrosis in the pancreatic parenchyma. These patients are difficult to treat because medical measures are rather limited analgesics, antidepressants (mainly tricyclics) and abstinence from alcohol. Pancreatic enzymes may be used on the theory that if you "rest" the pancreas with oral enzymes, the pain might improve. The results, however, are not great and, in my own experience, I haven't found such therapy to be impressive.
In some cases, pancreatic resection is necessary to relieve symptoms. This could include a Whipple's procedure for predominant pancreatic head disease, or resection of the tail of the pancreas for focal pancreatitis. In severe cases, either sub-total or total pancreatectomy is performed with resultant metabolic issues, which will require carefully supervised medical therapy, including insulin and pancreatic enzymes.
about pancreatic insufficiency?
Exogenous pancreatic enzymes, in optimal doses, should be prescribed with each meal. Some examples of commercially available preparations include Creon 20 and Cotazym 20. The "20" stands for lipase units in the 1,000s (e.g. Creon 20 contains 20,000 units of lipase), and they also contain other enzymes, including proteases. The typical dose is about 20-40,000 units of lipase with each meal; therefore, a patient would typically take one or two capsules.
Complications from chronic pancreatitis can arise and include common bile duct stricture and a pseudocyst. The latter is a cystic collection of pancreatic enzymes, which become circumscribed when mature. Any pseudocyst larger than five centimetres needs to be monitored closely and drained if it increases in size, causes pain or becomes infected. Other complications include duodenal stenosis causing gastric outflow obstruction, and splenic vein thrombosis, which may cause portal hypertension and gastric varices that bleed.
The prognosis for chronic pancreatitis is subject to a number of factors, including the patient's capacity to abstain from alcohol and minimize drug dependency, adequate control of exocrine and endocrine insufficiency, in addition to prompt recognition and management of complications.
Arni Sekar, MD, FRCPC is a consultant gastroenterologist and therapeutic endoscopist at the Ottawa Hospital, and Assistant Professor of Medicine at the University of Ottawa. He's been involved in the training of gastroenterology for 30 years. Many fellows have trained under him in therapeutic endoscopic procedures including ERCP.