ANATOMY AND PHYSIOLOGY
The gallbladder is located in the right upper quadrant of the abdomen beneath the liver. The cystic duct exits at the neck of the gallbladder and joins the common hepatic duct to form the common bile duct, which empties into the duodenum at the ampulla of Vater. This is surrounded by the sphincter of Oddi, which regulates bile flow into the duodenum (Fig. 7-1).
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Figure 7-1 • Duct system. From Anatomical Chart Company. |
Bile produced in the liver is stored in the gallbladder. Bile is important for the absorption of fat-soluble vitamins (A, D, E, and K). Cholecystokinin stimulates gallbladder contraction and release of bile into the duodenum. The spiral valves of Heister in the cystic duct prevent bile reflux into the gallbladder. Arterial supply is from the cystic artery, which most commonly arises from the right hepatic artery and courses through the triangle of Calot, which is bounded by the cystic duct laterally, the common hepatic duct medially, and the edge of the liver superiorly (Fig. 7-2).
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Figure 7-2 • The hepatocystic triangle (of Calot) is defined by three structures: cystic duct, common hepatic duct and lower liver edge. From Blackbourne LH. Advanced Surgical Recall. 2nd ed. Baltimore: Lippincott Williams & Wilkins, 2004. |
GALLSTONE DISEASE
Cholelithiasis is the presence of gallstones within the gallbladder. Choledocholithiasis refers to stones in the common bile duct (Fig. 7-3). Biliary colic is pain produced when the gallbladder contracts against a transiently obstructing stone in the neck of the gallbladder. There is no inflammatory or infectious process in biliary colic. Acute cholecystitis produces a constant pain and refers to inflammation and infection of the gallbladder; total or partial occlusion of the cystic duct is thought to be required. The most common organisms cultured during acute cholecystitis are Escherichia coli, Klebsiella, enterococci, Bacteroides fragilis, and Pseudomonas. Gallstones within the common bile duct are a major cause of pancreatitis, known as gallstone pancreatitis.
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Figure 7-3 • Biliary pathology. |
PATHOGENESIS
Gallstones are composed of cholesterol, calcium bilirubinate (pigment), or a mixture of both. Cholesterol stones make up approximately 75% of gallstones in Western countries. Stone formation occurs when bile becomes supersaturated with cholesterol. Cholesterol crystals then precipitate out of solution and agglomerate to form stones.
A high-cholesterol diet causes increased concentrations of cholesterol and may have a role in the pathogenesis of cholesterol stones. Pigment stones are composed of calcium bilirubinate and are either black or brown. Black pigment stones are usually found in the gallbladder and are associated with cirrhosis and hemolytic processes, such as sickle cell anemia, thalassemia, and spherocytosis. Brown stones are associated with chronic biliary tract infection and are often found in the bile ducts. Patients with indwelling biliary stents or with intraluminal nonabsorbable sutures in the ducts from prior surgery are prone to developing brown stones.
EPIDEMIOLOGY
Approximately 10% of the U.S. population has gallstones. The vast majority of people with stones are asymptomatic. Nevertheless, more than 600,000 chole- cystectomies are performed in the United States annually.
Gallstones are found more commonly in women. Risk factors include obesity, multiparity, chronic total
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parenteral nutrition use, high-dose estrogen oral contraceptives, rapid weight loss, diabetes, and increasing age. Some ethnic groups such as American Indians have very high prevalence rates. Spinal cord injury predisposes to cholesterol stones.
HISTORY
As stated, most patients with gallstones are asymptomatic. Patients with biliary colic usually complain of right upper quadrant or epigastric pain, often radiating around the right flank to the back. The pain is usually postprandial (occurring after eating). Pain episodes may be precipitated by fatty food intake and last several hours before resolving spontaneously. Associated nausea and vomiting are common.
Cholecystitis implies infection and inflammation of the gallbladder. The pain of cholecystitis is usually constant, with progressive worsening. Patients may have fever, chills, or sweats.
Choledocholithiasis can result in transient or complete blockage of the common bile duct. Patients may relate episodes of passing dark urine or light-colored stools caused by the inability of bile pigments to reach the gastrointestinal tract and from subsequent renal clearance. Choledocholithiasis can also lead to ascending cholangitis, demonstrated by right upper quadrant abdominal pain, fever, and chills.
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Pancreatitis owing to choledocholithiasis (gallstone pancreatitis) typically manifests with epigastric pain radiating to the back.
PHYSICAL EXAMINATION
Physical examination in simple biliary colic reveals right upper quadrant tenderness but no fever. Cholecystitis may be associated with fever and signs of peritoneal irritation, including right upper quadrant rebound and guarding. The classic finding in acute cholecystitis is the arrest of inspiration on deep right upper quadrant palpation as pressure from the examiner's hand contacts the inflamed gallbladder and peritoneum (Murphy sign). Choledocholithiasis may be associated with jaundice, in addition to signs of biliary colic. Cholangitis is classically marked by fever, right upper quadrant pain, and jaundice (Charcot triad). Progression of cholangitis to sepsis defines Reynolds pentad by adding hypotension and mental status changes to the triad. Patients with gallstone pancreatitis have epigastric tenderness. A palpable, nontender, distended gallbladder in the clinical setting of jaundice indicates malignant biliary obstruction (Courvoisier law).
DIAGNOSTIC EVALUATION
Laboratory examination in biliary colic is usually unremarkable. Cholecystitis usually manifests with increased white blood cell count and minor liver function test abnormalities. Choledocholithiasis is classically associated with increased serum bilirubin and alkaline phosphatase. Cholangitis usually causes elevated serum bilirubin and transaminase levels, as well as leukocytosis. Gallstone pancreatitis is accompanied by elevations in serum amylase and lipase.
Ultrasound is the best modality for imaging the gallbladder and bile ducts, having a sensitivity and specificity of 98% for the detection of gallstones. On ultrasound, the gallstones appear as opacities, with echoless shadows posteriorly (Fig. 7-4). Moving the patient during ultrasound examination often demonstrates migration of the stones to the dependent portion of the gallbladder. Ultrasound is also used for diagnosing acute cholecystitis. Fluid around the gallbladder (pericholecystic fluid), a thickened gallbladder wall, and an ultrasonographic Murphy sign all support the diagnosis of acute cholecystitis.
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Figure 7-4 • Gallstone. There is a hyperechoic stone (large arrow) in the dependent portion of the gallbladder, with a posterior shadow (small arrow). There is no thickening of the gallbladder wall or fluid around the gallbladder. From Harwood-Nuss A, Wolfson AB, Linden CH, et al. The Clinical Practice of Emergency Medicine. 3rd ed. Philadelphia: Lippincott Williams & Wilkins, 2001. |
When ultrasound findings are equivocal or acalculous cholecystitis is suspected, cholescintigraphy (e.g., hepatobiliary iminodiacetic acid scan) is almost 100% sensitive and 95% specific for acute cholecystitis.
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In this test, a radionucleotide that is injected intravenously is taken up in the liver and excreted into the biliary tree. If the cystic duct is obstructed, as in acute cholecystitis, the gallbladder does not fill, and the radionucleotide passes directly into the duodenum.
Choledocholithiasis can be diagnosed by intraoperative cholangiography at the time of surgery or preoperatively or postoperatively by endoscopic retrograde cholangiopancreatography (ERCP). ERCP is performed by using a specialized side-viewing endoscope to visualize the ampulla, where the pancreatic and biliary ducts enter the duodenum. Using a catheter passed through the endoscope, contrast media is injected retrograde and outlines the biliary tree and pancreatic duct (Fig. 7-5). Magnetic resonance cholangiopancreatography can noninvasively detect common bile duct stones; however, it lacks the therapeutic advantage of ERCP for stone extraction.
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Figure 7-5 • Endoscopic retrograde cholangiopancreatography removal of common bile duct stone using balloon-tip catheter. |
COMPLICATIONS
Most gallstones are quiescent. When cholecystitis develops, however, delayed diagnosis may result in gangrenous necrosis of the gallbladder wall with perforation, leading to localized abscess or frank biliary peritonitis. Emphysematous cholecystitis owing to Clostridium perfringens can be seen in diabetic patients.
Gallstone pancreatitis may occur as a result of a common duct stone causing blockage of the ampulla, theoretically resulting in bile reflux into the pancreatic duct or increased intraductal pressure. (See Chapter 9, Pancreas.)
Chronic perforation may result in a bilioenteric fistula. This occurs in older adult patients when a large gallstone erodes through the gallbladder wall and causes a fistula to form between the gallbladder and bowel (usually duodenum, rarely colon). The large stone can then pass out of the gallbladder, through the fistula and into the bowel, resulting in distal bowel obstruction (gallstone ileus). Stone obstruction of the small bowel typically occurs at the terminal ileum, whereas the large bowel obstruction typically occurs at the sigmoid colon. Pneumobilia and a smooth obstructing mass on imaging studies are classic findings.
TREATMENT
For patients with asymptomatic stones found on workup for other problems, the incidence of symptoms or complications is approximately 2% per year. Cholecystectomy is usually not advised for these patients. For individuals with biliary colic, laparoscopic cholecystectomy is a safe and effective procedure. This is performed electively in most cases. If the preoperative workup suggests that common duct stones may be present, either ERCP or intraoperative cholangiography should be performed. (See Appendix for a description of a typical laparoscopic cholecystectomy.)
Patients with acute cholecystitis should be adequately fluid resuscitated before surgery, as vomiting and diminished oral intake often results in dehydration. Intravenous antibiotics should be administered.
Laparoscopic cholecystectomy is the procedure of choice for removal of the gallbladder (Fig. 7-6). In the acute setting with gallbladder inflammation and infection, the procedure tends to be technically more difficult and has a higher rate of conversion to the open technique when compared with elective operations for biliary colic. Rarely, when patients are too ill to tolerate surgery, a cholecystostomy tube may be considered. This involves placing a percutaneous drain into the gallbladder lumen for decompression and drainage of pus. Cholecystectomy can then be performed when the patient is stable.
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Figure 7-6 • Laparoscopic cholecystectomy: four small incisions allow insertion of laparoscope and instruments for retraction & dissection. From Smeltzer SC, Bare BG. Textbook of Medical-Surgical Nursing. 9th ed. Philadelphia: Lippincott Williams & Wilkins, 2000. |
Patients with gallstone pancreatitis require aggressive fluid resuscitation and close observation. Fortunately, mild episodes account for 80% of cases; however, severe fulminant cases can be lethal. Intravenous antibiotics are
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only indicated in severe cases with pancreatic necrosis, infected necrosis, or infectious complications. Early ERCP is indicated in patients with signs of common bile duct obstruction (cholangitis, jaundice, dilated common duct on imaging studies) and in patients with severe disease. Once pancreatic inflammation subsides, cholecystectomy with intraoperative cholangiography should be performed during the same hospitalization to reduce the risk of recurrent pancreatitis and to rule out residual common duct stones. If stones are present, intraoperative common duct exploration or postoperative ERCP is performed. The risk of recurrent pancreatitis is approximately 40% within 6 weeks (see Chapter 9, Pancreas).
Cholangitis, usually caused by choledocholithiasis, requires rapid diagnosis and treatment. Gram-negative organisms are the most common cause. Prompt treatment with intravenous antibiotics, fluid resuscitation, and urgent biliary decompression and drainage are indicated. ERCP with sphincterotomy is the primary intervention. If the obstructing stone is unable to be extracted, an indwelling biliary stent can be passed proximal to the stone to allow decompression and drainage of infected bile into the duodenum. Other methods of decompression include percutaneous transhepatic drainage or open surgical drainage with common bile duct exploration and T-tube placement. Overall mortality is approximately 15%.
GALLBLADDER CANCER
EPIDEMIOLOGY
Carcinoma of the gallbladder is the most common malignancy of the biliary tract. Cancer of the gallbladder is three times more common in females. The incidence is 2.5 in 100,000. Risk factors include gallstones, porcelain gallbladder, and adenoma. One percent of all patients who undergo cholecystectomy for gallstones will be found to have gallbladder carcinoma.
PATHOLOGY
Adenocarcinoma is the most common histologic type. Approximately 80% are adenocarcinomas, 10% are anaplastic, and 5% are squamous cell.
HISTORY
Unfortunately, most patients usually present with late-stage disease complaining of vague right upper quadrant pain. Weight loss, anorexia, and nausea may also be present.
PHYSICAL EXAMINATION
A right upper quadrant mass may be present. Obstructive jaundice represents invasion or compression of the common bile duct. Ascites is seen in advanced cases.
STAGING
Staging of gallbladder carcinoma is as follows:
TREATMENT
The mainstay of treatment for gallbladder cancer is surgical, because early detection and complete resection
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provide the only chance for cure. The extent of resection is controversial but is based on the stage of disease. Options include simple cholecystectomy, radical resection of the gallbladder including partial hepatic resection, or palliative operation as symptoms arise.
Most cases of early-stage disease are found incidentally after elective laparoscopic cholecystectomy. If the cancer is stage I and confined to the mucosa/submucosa, then no additional surgery is indicated. For stage II and III lesions, where the muscle layer is involved, the en-bloc resection of the gallbladder with hepatic segments 4 and 5 as well as radical lymph node dissection is indicated. Overall, stage IV cancers show no benefit from attempts at radical resection (except perhaps in patients with T4N0 disease).
PROGNOSIS
Unless cancer is found incidentally at cholecystectomy for symptomatic gallstones, the chance of long-term survival is low. For all patients diagnosed with gallbladder cancer, only 4% will be alive after 5 years. Patients found to have incidentally noted in situ disease on cholecystectomy have survival rates of 88%. Overall survival rates of patients with American Joint Committee on Cancer stage I disease is 60%; stage II, 24%; stage III, 9%; and stage IV, 1%.
BILE DUCT CANCER
EPIDEMIOLOGY
Bile duct cancer (cholangiocarcinoma) is rare. Risk factors include ulcerative colitis, sclerosing cholangitis, and infection with Clonorchis sinensis. Patients with sclerosing cholangitis should be observed closely for evidence of cancer.
HISTORY
Patients with advanced disease typically complain of right upper quadrant pain. Biliary obstruction may lead to jaundice and pruritus.
PHYSICAL EXAMINATION
The patient may be jaundiced, with a palpable nontender distended gallbladder. If so, Courvoisier law states that the site of obstruction is in the common bile duct, distal to the confluence of the hepatic and cystic ducts.
DIAGNOSTIC EVALUATION
Laboratory studies are consistent with the chemical findings of obstructive jaundice. Ultrasound and computed tomography show evidence of biliary obstruction with dilated ducts, but percutaneous transhe-patic cholangiography or ERCP is usually necessary to demonstrate the lesion. With access to the biliary tree, brushings or biopsies can be performed for cytologic diagnosis.
TREATMENT
Unresectable tumors are usually treated with either endoluminal stenting to relieve obstruction or else with percutaneous catheter biliary drainage. Surgical treatment mostly depends on the location of the tumor within the extrahepatic bile duct. Tumors of the proximal and middle thirds of the duct are best treated with resection and reconstruction with Roux-en-Y hepaticojejunostomy (Fig. 7-7). Tumors of the distal lower third are best treated with pancreaticoduodenectomy (Whipple procedure; Fig. 7-8).
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Figure 7-7 • Choledochojejunostomy. Anastomosis of common bile duct to jejunum. From Blackbourne LH. Advanced Surgical Recall. 2nd ed. Baltimore: Lippincott Williams & Wilkins, 2004. |
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Figure 7-8 • Classic pancreaticoduodenectomy. Top left: The structures resected include the distal stomach; pylorus; entire duodenum; head, neck, and uncinate process of the pancreas with tumor (black); gallbladder; and distal extrahepatic biliary tree. Top right: The structures retained include the proximal stomach, body and tail of the pancreas, proximal biliary tree, and jejunum distal to ligament of Treitz. Bottom: The reconstruction is shown as a proximal end-to-end pancreaticojejunostomy, end-to-side hepaticojejunostomy, and a distal gastrojejunostomy. From Yeo C, Cameron JL. The pancreas. In: Hardy J, ed. Hardy's Textbook of Surgery. 2nd ed. Philadelphia: JB Lippincott Co, 1988:717-718. |
PROGNOSIS
Overall mortality is 90% at 5 years. The 5-year survival rate after proximal duct resection is approximately 5%, after middle duct resection is 10%, and after Whipple procedure for distal duct lesions is 30%.
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KEY POINTS