CHAPTER 39
CHOLECYSTITIS, CHOLANGITIS, AND JAUNDICE
Disorders of the biliary tract often demand the attention of the acute care surgeon. These disorders can run the gamut from the benign attack of biliary colic, to the rapidly fatal entity—suppurative cholangitis. However, attention to key features in the history and physical exam, when coupled with the appropriate labs and imaging tests, allows an accurate diagnosis and treatment plan in most instances.
ANATOMY
Simplistically, the biliary system can be thought of as the plumbing of the liver, providing drainage of bile into the intestines. Most surgical disorders of the biliary tract are secondary to an obstruction along this drainage tract. As such, the diagnosis and treatment of biliary disorders requires a thorough understanding of biliary anatomy.
Biliary Anatomy
The intrahepatic bile ducts course alongside their arterial and portal venous counterparts to form the portal triads of the liver parenchyma. These ducts coalesce into the right and left hepatic ducts. The caudate lobe has its own system of small ducts which drain directly into both the right and left main ducts. As the right and left hepatic ducts exit the liver, they remain sheathed in Glisson’s capsule, hiding them from direct view. The right duct has a short course outside the liver, whereas the left duct has a long extrahepatic course as it travels along the undersurface of the left lobe to the hilum. The point of biliary convergence into the main hepatic duct is variable; in some individuals the bifurcation is well outside the liver, while in others it is practically intraparenchymal.
The gallbladder is nestled along the undersurface of the liver at the junction of the right and left lobes. It is separated from the liver parenchyma by the cystic plate, which is a continuation of Glisson’s capsule. A common mistake during cholecystectomy is to dissect the gallbladder en bloc with the cystic plate off the liver bed, which leads to unnecessary bleeding. The true plane for cholecystectomy is found close to gallbladder wall, leaving the whitish cystic plate intact on the liver.
The cystic duct empties into the common hepatic duct, forming the common bile duct (CBD). The length of the cystic duct may be short, or it may run along the hepatic duct for some distance before joining it. This anatomical variability is of paramount significance during cholecystectomy when extreme care should be taken to avoid inadvertent injury to the CBD while ligating the cystic duct.
The main bile duct runs vertically in the hilum, anterior to the portal vein and lateral to the hepatic artery. The normal diameter of the CBD is approximately 5 mm, although it can be slightly wider in the elderly.1 A useful rule of thumb is that the diameter of the bile duct increases 1 mm for every decade of life. While an 8 mm CBD could be a normal finding in an 80-year-old, it should be considered dilated in an otherwise healthy 30-year-old. The cystic duct usually measures 3 mm in diameter. Thus, any difficulty in ligation of the cystic duct with a 5-mm clip applier should be a red flag to the surgeon that the structure in question may in fact be the CBD.
When dealing with the biliary tree, anatomical variations are common and unpredictable. If appropriate vigilance is not exercised, an elective cholecystectomy can become a disaster with injury to the bile ducts, arteries or both. It cannot be stressed enough that the possibility of anomalies in biliary anatomy must be foremost in the mind of any surgeon performing a hepatobiliary procedure. Moreover, awareness of these variations is essential for the proper interpretation of an intraoperative cholangiogram.
A relatively common and potentially critical variation is the low-inserting posterior sectoral duct. In most individuals, this duct, which drains segments VI and VII of the liver, joins the anterior sectoral duct to form the right hepatic duct. However, in some individuals, this duct travels independently to enter the common hepatic duct, the cystic duct, or even the CBD as a separate structure. This low-inserting posterior duct may be injured during cholecystectomy leading to a persistent bile leak or atrophy of intrahepatic liver segments.
Arterial Anatomy
In most instances, the hepatic artery arises from the celiac trunk. However, the right hepatic artery (or even the entire hepatic) may originate from the superior mesenteric artery. In these cases, the hepatic artery will lie posterior to the CBD for its entire length. As a result, the cystic artery’s position within Calot’s triangle will be altered, which may lead to confusion during cholecystectomy.
Another common variant is the accessory left hepatic artery. Instead of arising from the common hepatic artery, this vessel arises from the left gastric artery. In most cases, this is actually an accessory artery which supplies segments II and III, while a smaller branch off the common hepatic still supplies segment IV.
After the hepatic artery bifurcates, the right hepatic artery dives behind the CBD where is becomes vulnerable to injury during cholecystectomy. The right hepatic artery sometimes curves near the cystic duct in its course towards the liver; this has been termed “Moynihans’ hump.”2,3 In these cases, the cystic artery is short, and attention must be paid to avoid either injury to the right hepatic artery or ligation when mistaken for the cystic artery. Anterior and posterior branches of the cystic artery are often identifiable; these can originate from the main cystic artery or may arise independently from the right hepatic artery.
When an injury to the CBD occurs in the course of a cholecystectomy, it is often a paired injury; that is, the common duct is mistaken for the cystic duct and as part of the illusion and the right hepatic artery is mistaken for the cystic artery. Therefore, in all cases of iatrogenic bile duct injury, it is important to investigate the patency of the right hepatic artery.4,5
The venous drainage from the gallbladder is directly into the liver parenchyma. Variations in hepatic venous and portal venous anatomy are common, but rarely clinically relevant to the acute care surgeon. However, special mention of the anatomy of the middle hepatic vein is warranted. The course of the middle hepatic vein within the hepatic parenchyma becomes quite superficial as it nears the gallbladder fossa. The vein can be injured during cholecystectomy if the surgeon veers off the correct plane and violates the liver parenchyma. Dark venous blood quickly fills the field, and can turn an ambulatory case into one with major blood loss. Direct pressure applied to the liver bed usually allows temporary hemostasis while assistance is en route. Depending upon the degree of injury, definitive control can be obtained with either argon beam coagulation, clipping, or with a parenchymal suture.
PHYSIOLOGY
Hepatocytes import unconjugated bilirubin from the plasma and conjugate it with glucuronic acid to make it water soluble. Conjugated bilirubin is then excreted into the bile canaliculi, and is eventually emptied into the duodenum. Through this process, approximately 1 L of bile is produced per day.6 The function of bile is (1) to deliver bile salts to the intestines to aid in digestion of fats, (2) to excrete bilirubin, which is an oxidative product of heme, resulting from the destruction of senescent red blood cells, and (3) to excrete toxins.
Jaundice is the physical manifestation of hyperbilirubinemia, and usually becomes noticeable when the bilirubin level exceeds 3 mg/dL. Jaundice can result from an aberration anywhere along the process from bile production through excretion. The etiology of jaundice can be determined by whether the hyperbilirubinemia is predominantly unconjugated or conjugated. Unconjugated hyperbilirubinemia is seen with overproduction of bilirubin, impaired uptake of bilirubin, or impaired conjugation of bilirubin. Conjugated hyperbilirubinemia is seen with impaired excretion or obstruction of the biliary tree.
A conjugated hyperbilirubinemia can also be seen in cholestasis. In this clinical scenario, the ratio of total to direct bilirubins will mimic an obstructive pattern, although no downstream obstruction is present and biliary dilatation will accordingly be absent. Any systemic inflammatory process can affect bile secretion and result in cholestatic jaundice. This is often the case in the chronically ill or septic intensive care unit (ICU) patient whose labs demonstrate direct hyperbilirubinemia and otherwise unimpressive liver function studies. This cholestatic jaundice may be profound and will not resolve until the underlying process is controlled.
Surgical emergencies of the biliary system are usually due to acute obstruction of the biliary tree. Obstructive jaundice has several physiologic consequences which have relevance to surgeons, including aberrations in cardiac output, coagulation, renal function, wound healing, and the immune system. These issues should be considered for any jaundiced patient on the surgical service.
Cardiac Physiology
Obstruction of the biliary system can cause hemodynamic disturbances including decreased peripheral vascular resistance and depressed cardiac contractility.7,8 Jaundiced patients display more labile blood pressure and are more susceptible to shock. Obstructed patients who undergo biliary decompression can become acutely hypotensive. It is unclear if this is due to cardiac lability, or secondary to instrumentation-induced bacteremia.
Coagulation
In patients with obstructive jaundice, impaired vitamin K absorption from the gut occurs due to a lack of intestinal bile, and is evidenced by a prolonged prothrombin time.9 The effect is reversible with parenteral administration of vitamin K. There is little risk to vitamin K administration, therefore any jaundiced patient undergoing an operation should receive preoperative supplementation.
Renal
The decreased cardiac function associated with jaundice leads to renal hypoperfusion and acute renal failure. Hepatorenal syndrome is well-known in advanced cirrhotics, but renal insufficiency can also occur in patients with obstructive jaundice. When undergoing surgery, special attention needs to be paid to maintenance of intravascular volume. The mortality rate of patients with obstructive jaundice who develop renal failure is close to 70%.10
Wound Healing
Delayed wound healing and a high incidence of wound dehiscence have been reported in patients undergoing surgery to relieve obstructive jaundice. This may be related to decreased activity of the enzyme prolyl hyrdoxylase, which is required for normal collagen synthesis, in the skin of jaundiced patients. Levels of this enzyme return to normal following relief of the obstruction.11 Accordingly, meticulous wound closure technique must be used in this group of patients.
Immune System
Jaundiced patients have numerous defects in cellular immunity which make them prone to infection; including impaired T-cell proliferation, decreased neutrophil chemotaxis, and defective phagocytosis.12–14 In addition, bacterial translocation from the gut is increased when bile is absent the intestinal lumen. Jaundiced patients should be considered immunocompromised.
IMAGING OF THE BILIARY TREE
Ultrasound
Ultrasound is inexpensive, fast, and noninvasive making it the ideal method for visualization of the gallbladder and intrahepatic bile ducts. Views of the more distal CBD are usually obscured by overlying bowel gas and cannot be adequately examined by ultrasound. In addition, it is of limited use in obese patients and in cirrhotics because of the poor image quality caused by these conditions. Lastly, it is important to keep in mind that sonography is highly user-dependent, and thus only as reliable as the skill of the user.
Stones and sludge in the gallbladder are hyperechoic and cast an acoustic shadow. The sensitivity of ultrasound in the detection of stones is high, and the lack of stones on an ultrasound should bring into question the diagnosis of biliary colic or cholecystitis in an otherwise healthy patient.
Sonographic findings suggestive of acute cholecystitis are: (1) the presence of stones or sludge, (2) gallbladder wall thickening >4 mm, (3) pericholecystic fluid, and (4) a sonographic Murphy’s sign, or tenderness elicited when the sonographer presses the ultrasound probe onto the visualized gallbladder.
When making a diagnosis of cholecystitis, it is important to note that bilirubin levels should be normal and on imaging the CBD should be of normal size. If jaundice or a dilated CBD is seen in a patient with abdominal pain, cholangitis must be suspected instead. Rarely, a markedly edematous gallbladder or a large stone impacted within the gallbladder can cause external compression of the CBD; a process known as Mirizzi’s syndrome. In this case, intrahepatic biliary dilatation may be seen on ultrasound; however the CBD distal to the gallbladder (downstream from the obstruction) should not be dilated.
Computed Tomography
Computed tomography (CT) is not the initial test of choice for evaluation of the biliary system since approximately one-third of stones are not dense enough to be seen on CT.15 In addition, the cost and radiation exposure make CT undesirable as first-line imaging. Nevertheless, in reality, CT is often the first test performed on patients with abdominal pain.
In acute cholecystitis, CT will demonstrate a thickened gallbladder; streaking and edema may be present in the pericholecystic fat. However, the CT appearance of the gallbladder can be misleading: the gallbladder may become slightly thick-walled due to other intraabdominal processes (e.g., ascites) which can mislead the clinician. Alternatively, the CT appearance of the gallbladder may be underwhelming even in genuine cases of acute cholecystitis. The absence of stones on CT scan should never be used in clinical decision making, since stones may be missed on CT.
Despite its limitations in stone-related disease, CT is well-suited to identify tumors and other non-stone sources of obstruction of the biliary tree. CT is also useful in patients with postoperative complications, since it can demonstrate the presence of a bile collection (biloma), hematoma, or vascular injury. When present, pneumobilia is easily seen with CT. While this is a normal finding following biliary enteric bypass or sphincterotomy, in patients who have not been instrumented, pneumobilia may indicate the presence of a biliary enteric fistula or may be a manifestation of suppurative cholangitis.
Scintigraphy
Hepatobiliary scintigraphy involves the intravenous injection of a radiopharmaceutical tracer (e.g., technetium-iminodiacetic acid compound) which is taken up by the liver and excreted into the bile. Sequential images show activity in the liver, then in the bile ducts and gallbladder, and eventually in the small bowel. The gallbladder is seen within 30 minutes, and the intestines within 60 minutes in most subjects. Nonvisualization of the gallbladder implies obstruction of the cystic duct and, in the appropriate clinical setting, confirms the presence of cholecystitis. Scintigraphy is the most accurate test for acute cholecystitis and sensitivity rates exceed 95%.16 Specificity rates are also high, but false positives can be seen during prolonged fasting, and when acute pancreatitis hypoalbuminemia is present. Scintigraphy can be a useful tool for the confirmation of biliary tract pathology in patients where the clinical picture is unclear. It is particularly useful to confirm acalculous cholecystitis, where ultrasound findings may be equivocal.
Cholangiography
Direct cholangiography can be obtained by injection of contrast (1) percutaneously through the liver, (2) retrograde via the ampulla during endoscopic retrograde cholangiopancreatography (ERCP), or (3) directly into the biliary tree during surgery. Cholangiography provides the highest resolution imaging of biliary anatomy. The technique of intraoperative cholangiography is discussed later. Noninvasive imaging of the biliary tree can be obtained by magnetic resonance cholangiopancreatography (MRCP). However, unlike ERCP, MRCP does not provide the opportunity for a concomitant therapeutic component.
DISORDERS OF THE GALLBLADDER
Surgical pathology of the biliary tree usually results from physical obstruction of bile drainage; most often due to stones. Treatment depends upon the site of obstruction and whether there is concomitant infection.
Asymptomatic Cholelithiasis
Bile is maintained in a liquid state by the delicate balance of bile salts, lecithin, and cholesterol. Cholelithiasis results when these factors become unbalanced. The vast majority of gallstones are cholesterol stones which form in the gallbladder. Pigment stones, which form secondary to hemolysis, are fairly unusual. Results from autopsy studies and ultrasound screening studies suggest that cholelithiasis is present in 10%-20% of the population. Surveillance of individuals with known gallstones suggests that only 15% of patients ever develop symptoms.17,18 Gallstones are often detected incidentally on an ultrasound or CT obtained for other reasons. These asymptomatic stones do not require any surveillance or surgical follow-up.
Biliary Colic
Gallstones may intermittently obstruct the cystic duct, causing pain known as biliary colic. This term is actually a misnomer, since within each attack the pain is constant, not colicky. When the cystic duct is obstructed, the patient usually experiences right upper-quadrant or epigastric pain that typically lasts for 4–6 hours. The pain may radiate to the back, shoulder or the subscapular area. Nausea is usually present, and vomiting may occur, but is not the dominant symptom. Classically, the pain starts after a fatty meal, due to cholecystokinin release. The resulting contraction of the gallbladder against an obstructed cystic duct causes intense pain. The pain often subsides without treatment when the offending stone slips back into the gallbladder, thereby resolving the obstruction.
Some patients with biliary colic will develop intractable pain with a crescendo of symptoms. These patients may experience symptoms with nearly every meal and often present with documented weight loss or dehydration. Cholecystectomy should be performed expeditiously in these cases.
It is important to note that in biliary colic, while obstruction of the cystic duct is present, infection is not. Accordingly, the treatment is does not require antibiotics, only bowel rest with IV hydration, pain control, and elective cholecystectomy. Once infection develops, right upper-quadrant tenderness, leukocytosis and fever invariably follow. With these findings, biliary colic has now evolved into acute cholecystitis. Careful physical examination and the use of ultrasonography will usually distinguish between these two entities.
Acute cholecystitis occurs when obstruction of the cystic duct is accompanied by infection of the bile and gallbladder. These patients will present with complaints of pain and nausea similar to biliary colic; however the pain of cholecystitis will persist for 1–2 days if left untreated. On physical examination, right upper quadrant tenderness will be present due to inflammation of the gallbladder. A classic Murphy’s sign describes the focal gallbladder tenderness that is elicited when, upon taking a deep breath, the patient abruptly halts inspiration due to the sudden pain that occurs when the descending gallbladder hits the examiner’s hand, which is pressed into the right subcostal margin. Fever and mild leukocytosis are typically present, consistent with infection. Liver function tests should be normal, except in rare cases of Mirizzi’s syndrome described below.
The treatment of acute cholecystitis generally consists of antibiotics, bowel rest with IV hydration, pain control, and cholecystectomy. Common biliary pathogens are the enteric gram-negative organisms including Escherichia coli and Klebsiella.19 Bile is normally sterile; the sphincter of Oddi prevents enteric bacteria from entering the biliary system, and the flow of bile helps prevent infection with its mechanical flushing action. However, when cystic duct obstruction occurs, as in cholecystitis, stasis of bile within the gallbladder allows bacterial proliferation and infection.
The definitive treatment of cholecystitis is cholecystectomy. In the past, delayed cholecystectomy was advocated as safer than cholecystectomy performed during the acute inflammatory phase. However, a meta-analysis of 12 prospective, randomized trials showed that prompt cholecystectomy does not result in higher rates of CBD injury, and actually results in substantially lower length of stay and decreased hospital costs.20,21 Therefore, unless there are medical contraindications, early cholecystectomy should be performed.
Variations of Cholecystitis
Routine cholecystitis is relatively straightforward in its diagnosis and treatment. However, certain types of cholecystitis can be more challenging to identify and manage.
Mirizzi’s Syndrome
Mirizzi’s syndrome, occurs when an inflamed gallbladder causes external compression of the CBD, thereby leading to obstructive jaundice (Fig. 39.1).22 The compression may be due to an enlarged and inflamed gallbladder, or from a large stone impacted in the gallbladder neck. Mirizzi’s syndrome is rare, one study states that it occurs in approximately 0.1% of patients with gallstone disease23; therefore, Mirizzi’s syndrome is diagnosis of exclusion. Direct hyperbilirubinemia should never be attributed to Mirizzi’s syndrome unless other causes of obstructive jaundice have been excluded, since the consequences of a missed cholangitis can be severe.
FIGURE 39.1. Mirizzi’s syndrome. Asterisk marks area of CBD compression by the infundibulum of the gallbladder.
Acalculous Cholecystitis
Acalculous cholecystitis occurs almost exclusively in patients with severe comorbidities, and is classically seen in hospitalized patients who are septic, receiving parenteral nutrition, on vasopressors, or who have suffered major trauma or burns. The precise etiology of this entity is unknown, but theories include gallbladder ischemia and presence of inspissated bile.24,25 Since the cystic artery is a small terminal vessel, global hypoperfusion is thought to result in gallbladder wall ischemia and eventually necrosis. The diagnosis of acalculous cholecystitis is challenging because, by definition, it occurs in patients who are ill, have confounding histories, and are usually unable to verbalize their symptoms. Acalculous cholecystitis is often found as the result of a CT done for fever of unknown origin in a patient in the ICU. Gangrene and perforation occur commonly, due to the frequent delay in diagnosis.
Often, ultrasound or CT show only a distended, mildly thickened gallbladder. Diagnosis can be difficult since gallbladder distension may simply be due to a prolonged NPO status with total parenteral nutrition, and not cholecystitis. Nuclear scintigraphy (e.g., HIDA scan) can be useful in unclear cases of acalculous cholecystitis. Since many patients with acalculous cholecystitis are quite ill, often immediate cholecystectomy is not possible or prudent. In this setting, imaging-guided percutaneous drainage of the gallbladder allows drainage of bile and release of the infection. This treatment is sufficient in most cases, less commonly a cholecystectomy may be required if tissue necrosis has set in. If the patient resolves the episode of acalculous cholecystitis with percutaneous cholecystostomy, cholecystectomy is seldom necessary at a later time.
Gangrenous Cholecystitis
Gangrenous cholecystitis occurs when infection and inflammation cause thrombosis of the cystic artery; this leads to ischemia and gangrene of the gallbladder wall, eventually resulting in liquefaction necrosis and perf oration of the gallbladder. Gangrene occurs first at fundus of the gallbladder because this is the most distant site from the blood supply of the cystic artery. In patients with free perforation, bile stained ascites may be present. Gangrenous cholecystitis is more common in diabetics due to their underlying small vessel disease.26 Once gangrene has developed, a cholecystostomy tube will most likely be insufficient to halt the process. The problem that arises is ascertaining which patients can be managed with a tube cholecystostomy and which cannot. If the patient with acute or gangrenous cholecystitis has not improved within 24 hours of placement of the tube, it is possible that tissue necrosis is present, for which the patient should undergo urgent cholecystectomy. Other causes for the lack of response to cholecystostomy include malposition or dislodgement of the catheter or incorrect diagnosis of cholecystitis.
The imaging appearance of gas within the gallbladder wall is pathognomonic of emphysematous cholecystitis and indicates the presence of gas-forming bacteria such as clostridia species, E. coli, or Klebsiella.27 The infection progresses in stages from the presence of gas in the gallbladder lumen, to within the gallbladder wall, and ultimately into pericholecystic tissues.28 The presence of gas can obscure ultrasound imaging of the gallbladder, however the diagnosis is easily made with CT (Fig. 39.2). Emphysematous cholecystitis occurs more commonly in elderly or diabetic males, and is more frequently associated with acalculous cholecystitis.29 Expeditious cholecystectomy is warranted if the patient will tolerate the operation.
FIGURE 39.2. Emphysematous cholecystitis on CT.
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