32

Gallbladder and the Extrahepatic

Biliary System
chapter Kelly R. Haisley and John G. Hunter

Anatomy 1393 Endoscopic Choledochoscopy / 1400 Common Bile Duct Drainage

Gallbladder / 1393 Endoscopic Ultrasound / 1401 Procedures / 1414
Bile Ducts / 1394 Percutaneous Transhepatic Other Benign Diseases
Anatomic Variants / 1396 Cholangiography / 1401 and Lesions 1414
Physiology 1396 Gallstone Disease 1401 Biliary Dyskinesia and Sphincter
Bile Formation and Composition / 1396 Prevalence and Incidence / 1401 of Oddi Dysfunction / 1414
Gallbladder Function / 1397 Natural History / 1401 Acalculous Cholecystitis / 1415
Sphincter of Oddi / 1397 Gallstone Formation / 1402 Choledochal (Biliary) Cysts / 1417
Symptomatic Gallstones / 1404 Primary Sclerosing Cholangitis / 1417
Diagnostic Studies 1398
Cholangiohepatitis / 1410 Bile Duct Strictures / 1418
Blood Tests / 1398
Transabdominal Ultrasonography / 1398 Procedural Interventions Injury to the Biliary Tract 1419
Computed Tomography / 1398 for Gallstone Disease 1410 Gallbladder / 1419
Hepatobiliary Scintigraphy / 1399 Percutaneous Transhepatic Extrahepatic Bile Ducts / 1419
Magnetic Resonance Imaging / 1399 Cholecystostomy Tubes / 1410 Tumors 1421
Endoscopic Retrograde Endoscopic Interventions / 1410 Carcinoma of the Gallbladder / 1421
Cholangiopancreatography / 1400 Cholecystectomy / 1410 Cholangiocarcinoma / 1423
Common Bile Duct Exploration / 1413

ANATOMY Rarely, the gallbladder has a complete peritoneal covering on

all sides and is suspended in a mesentery off the inferior surface
Gallbladder of the liver.
The gallbladder is a pear-shaped sac that measures around 7 to The mucosal lining of the gallbladder is formed by a single,
10 cm long, with an average capacity of 30 to 50 mL. When highly redundant, simple columnar epithelium that contains
obstructed, the gallbladder can distend markedly and contain cholesterol and fat globules. The mucus secreted into the gall-
up to 300 mL of fluid. The gallbladder is located in an anatomic bladder originates in tubuloalveolar glands that are found in the
fossa on the inferior surface of the liver. Cantle’s line, a vertical mucosal lining of the infundibulum and neck of the gallbladder,
plane running from the gallbladder fossa anteriorly to the infe- but are absent from the body and fundus. The epithelial lining of
rior vena cava (IVC) posteriorly divides the liver into right and the gallbladder is supported by a lamina propria. The gallblad-
left lobes. The gallbladder itself is divided into four anatomic der differs histologically from the rest of the gastrointestinal
areas: the fundus, the body, the infundibulum, and the neck. (GI) tract in that it lacks a muscularis mucosa and submucosa.
The fundus is the rounded, blind end that normally extends 1 to The muscular layer has circular, longitudinal, and oblique
2 cm beyond the liver’s margin and contains most of the smooth fibers, but without well-defined layers. The adventitia contains
muscle of the organ. The body functions as the main storage connective tissue, nerves, vessels, lymphatics, and adipocytes.
area and contains most of the elastic tissue allowing for disten- The gallbladder is covered by serosa except where the gallblad-
tion. As the body tapers towards the neck of the gallbladder, der is embedded in the liver.
a mucosal outpouching is present at the junction of the neck The cystic artery that supplies the gallbladder is usually a
and the cystic duct, known as the infundibulum or Hartmann’s branch of the right hepatic artery (>90% of the time). The course
pouch. Beyond this, the neck of the gallbladder lies in the deep- of the cystic artery may vary, but it nearly always is found within
est part of the gallbladder fossa and can extend slightly into the the hepatocystic triangle (triangle of Calot), the area bound by
free portion of the hepatoduodenal ligament, where it connects the cystic duct, common hepatic duct, and the inferior edge
with the cystic duct (Fig. 32-1).1 of the liver. When the cystic artery reaches the neck of the gall-
The same peritoneal lining that covers the liver extends bladder, it divides into anterior and posterior divisions. Venous
to cover the fundus and the inferior surface of the gallblad- return is carried either through small veins that enter directly
der. Occasionally, part or all of the gallbladder is embedded into the liver or, rarely, to a large cystic vein that carries blood
deep inside the liver parenchyma (an intrahepatic gallbladder). back to the portal vein. Gallbladder lymphatics drain into nodes
 Key Points
1 The physiology of the gallbladder, biliary tree, and sphincter (Calot’s) triangle to obtain the critical view of safety and
of Oddi are regulated by a complex interplay of hormones careful identification of the anatomic structures are keys
and neuronal inputs designed to coordinate bile release with to avoiding these injuries. Once a bile duct injury is diag-
food consumption. Dysfunctions related to this activity are nosed, the best outcomes are seen at large referral centers
linked to the development of gallbladder pathologies as de- with experienced biliary surgeons, and patient transfer may
scribed in this chapter. be required.
2 In Western countries, the most common type of gallstones 5 The main risk factor for gallbladder disease in Western coun-
are cholesterol stones. The pathogenesis of these stones tries is cholelithiasis. The main complications include cho-
relates to supersaturation of bile with cholesterol and sub- lecystitis, choledocholithiasis, cholangitis, and biliary
sequent precipitation. pancreatitis. Cholelithiasis is also the major risk factor for
3 Laparoscopic cholecystectomy has been demonstrated to be the development of gallbladder cancer.
safe and effective, and it has become the treatment of choice 6 Carcinomas of the gallbladder or bile ducts generally have a
for symptomatic gallstones. Knowledge of the various ana- poor prognosis because patients usually present late in the
tomic anomalies of the cystic duct and artery is critical in disease process and have poor response to chemotherapy
guiding the dissection of these structures and avoiding injury and radiation. Surgery offers the best chance for survival and
to the common bile duct during cholecystectomy. has good long-term outcomes in patients with early-stage
4 Common bile duct injuries, although uncommon, can be disease.
devastating to patients. Proper exposure of the hepatocystic

at the neck of the gallbladder. Frequently, a visible lymph node and sensory innervation through nerve fibers running largely
(Lund’s or Mascagni’s node, often referred to as Calot’s node) through the gastro hepatic ligament. Parasympathetic (cholinergic)
overlies the insertion of the cystic artery into the gallbladder fibers arise from the hepatic branches of the vagus nerve to
wall. The gallbladder receives parasympathetic, sympathetic stimulate activity in the gallbladder, bile ducts, and liver. These
vagal branches also have peptide-containing nerves contain-
ing agents such as substance P, somatostatin, enkephalins, and
vasoactive intestinal polypeptide (VIP).2 The sympathetic and
b
sensory braches of the gallbladder, liver, and bile ducts pass
a through the celiac plexus and control gallbladder relaxation and
m
mediate the pain of biliary colic.
l
d
k c
o q Bile Ducts
e
The extrahepatic biliary tree consists of the right and left hepatic
j
ducts, the common hepatic duct, the cystic duct, and the com-
h mon bile duct. Exiting the liver, the left hepatic duct is longer
r than the right and has a greater propensity for dilatation as a
t f
consequence of distal obstruction. The two ducts join close to
g their emergence from the liver to form the common hepatic
n duct. The common hepatic duct typically extends 1 to 4 cm, has
i
p
a diameter of approximately 4 mm, and lies anterior to the portal
s
vein and to the right of the hepatic artery.
The cystic duct exits the gallbladder and joins the common
hepatic duct at an acute angle to form the common bile duct.
The segment of the cystic duct immediately adjacent to the gall-
bladder neck bears a variable number of mucosal folds called
the spiral valves of Heister. While they do not have any valvular
function, they can make cannulation of the cystic duct difficult.
The length and course of the cystic duct can be quite variable. It
Figure 32-1. Anterior aspect of the biliary anatomy. a = right hepatic
may be short or absent and have a high union with the hepatic
duct; b = left hepatic duct; c = common hepatic duct; d = portal vein;
e = proper hepatic artery; f = gastroduodenal artery; g = right gastro- duct, or it may be long and running parallel to, behind, or spiral-
epiploic artery; h = common bile duct; i = fundus of the gallbladder; ing around to the common hepatic duct before joining it, some-
j = body of gallbladder; k = infundibulum of the gallbladder; l = cystic times as far distally as at the duodenum. Variations of the cystic
duct; m = cystic artery; n = superior pancreaticoduodenal artery; duct and its point of union with the common hepatic duct are
o = neck of the gallbladder; p = pancreatic duct; q = common hepatic surgically important and misidentification can lead to bile duct
artery; r = right gastric artery; s = ampulla of Vater; t = supraduodenal injuries (Fig. 32-2).
artery. Note the situation of the hepatic bile duct confluence anterior The union of the cystic duct and the common hepatic duct
to the right branch of the portal vein, and the posterior course of the marks the start of the common bile duct. This segment is typi-
1394 right hepatic artery behind the common hepatic duct. cally about 7 to 11 cm in length and 5 to 10 mm in diameter,
 1395

CHAPTER 32 GALLBLADDER AND THE EXTRAHEPATIC BILIARY SYSTEM

A B C D

E F G H

Figure 32-2. Variations of the cystic duct anatomy. A. Low junction between the cystic duct and common hepatic duct. B. Cystic duct adher-
ent to the common hepatic duct. C. High junction between the cystic and the common hepatic duct. D. Cystic duct drains into right hepatic
duct. E. Long cystic duct that joins common hepatic duct behind the duodenum. F. Absence of cystic duct. G. Cystic duct crosses posterior
to common hepatic duct and joins it anteriorly. H. Cystic duct courses anterior to common hepatic duct and joins it posteriorly.

though its diameter can increase slightly with age and follow- lateral walls of the common duct (sometimes referred to as
ing cholecystectomy. The upper third (supraduodenal portion) 3 o’clock and 9 o’clock). The nerve supply to the common bile
passes downward in the free edge of the hepatoduodenal liga- duct is the same as for the gallbladder, with the density of nerve
ment, to the right of the hepatic artery and anterior to the portal fibers and ganglia increasing near the sphincter of Oddi.1,2
vein. The middle third (retroduodenal portion) of the common
bile duct curves behind the first portion of the duodenum and
diverges laterally from the portal vein and the hepatic arteries. Duodenal wall
The lower third (pancreatic portion) can curve behind the head
Common
of the pancreas in a groove, or traverse through it to enter the
bile duct
wall of the second portion of the duodenum. The duct then runs
obliquely downward within the wall of the duodenum for 1 to
2 cm before opening on a papilla of mucous membrane (ampulla
of Vater), about 10 cm distal to the pylorus.
Duodenum
The union of the common bile duct and the main pan-
creatic duct follows one of three configurations. In about 70%
of people, these ducts unite outside the duodenal wall and tra- Ampulla of
verse the duodenal wall as a single duct. In about 20%, they Vater Pancreatic duct
join within the duodenal wall and have a short or no common
duct, but open through the same opening into the duodenum. In
about 10%, they exit via separate openings into the duodenum,
termed pancreas divisum. The sphincter of Oddi, a thick coat of
circular smooth muscle, surrounds the common bile duct at the
Sphincter
ampulla of Vater (Fig. 32-3). It controls the flow of bile, and in
of Oddi
some cases pancreatic juice, into the duodenum.
The extrahepatic bile ducts are lined by a columnar mucosa
with numerous mucous glands that are concentrated in the com-
mon bile duct. A fibro areolar tissue containing scant smooth
muscle cells surrounds the mucosa. A distinct muscle layer is
not present in the human common bile duct. The arterial supply
to the bile ducts is derived from the gastroduodenal and the right
hepatic arteries, with major trunks running along the medial and Figure 32-3. The sphincter of Oddi.
1396 Anatomic Variants
The classic description of the extrahepatic biliary tree and its
arteries applies only in about one-third of patients.3 The gall-
bladder may have abnormal positions, be intrahepatic, be rudi-
mentary (a small, nonfunctional hypoplastic remnant), or have
anomalous forms or duplications. A partially or completely
intrahepatic gallbladder is associated with an increased inci-
dence of cholelithiasis, and may be encountered at the time of
cholecystectomy. Isolated congenital absence of the gallblad-
der is very rare, with a reported incidence of 0.03%. Before the A B
diagnosis is made, the presence of an intrahepatic gallbladder or
PART II

anomalous position must first be ruled out. Duplication of the

gallbladder with two separate cavities and two separate cystic
ducts has an incidence of about one in every 4000 persons. This
occurs in two major varieties: the more common form in which
each gallbladder has its own cystic duct that empties indepen-
SPECIFIC CONSIDERATIONS

dently into the same or different parts of the extrahepatic biliary

tree, and the less common variant in which the two cystic ducts
merge before they enter the common bile duct. Duplication is C D
only clinically important when some pathologic process affects
one or both organs. Even rarer variants include a left-sided
gallbladder (often with a cystic duct that empties into the left
hepatic or common bile duct), retrodisplacement of the gall-
bladder at the posterior-inferior surface of the liver, transverse
positioning of the gallbladder, or a floating gallbladder in which
the gallbladder is hanging by a mesentery (Fig. 32-4).
Additional small bile ducts (of Luschka) may drain directly
from the liver fossa into the body of the gallbladder. If present,
but not recognized at the time of a cholecystectomy, a bile leak
E F
and subsequent accumulation of bile (biloma) may occur in the
abdomen. An accessory right hepatic duct occurs in about 5% of Figure 32-5. Variations in the arterial supply to the gallbladder. A.
cases. Variations in how the common bile duct enters the duode- Cystic artery from right hepatic artery, about 80% to 90%. B. Cystic
num are described earlier, in the “Bile Ducts” section. artery off the right hepatic artery arising from the superior mesenteric
Anomalies of the hepatic artery and the cystic artery are artery (accessory or replaced), about 10%. C. Two cystic arteries, one
quite common, occurring in as many as 50% of cases. While the from the right hepatic, the other from the common hepatic artery,
right hepatic artery usually originates from the proper hepatic rare. D. Two cystic arteries, one from the right hepatic, the other from
branch of the celiac trunk, up to 20% of patients will have a the left hepatic artery, rare. E. The cystic artery branching from the
replaced right hepatic artery coming off the superior mesenteric right hepatic artery and running anterior to the common hepatic duct,
artery. In about 5% of cases, there are two right hepatic arteries, rare. F. Two cystic arteries arising from the right hepatic artery, rare.
one from the proper hepatic artery and the other from the superior
mesenteric artery (accessory right hepatic artery). While the right PHYSIOLOGY
hepatic artery typically runs posterior to the bile ducts, variations
may allow it to course anterior to the common duct, making it Bile Formation and Composition
vulnerable during surgical procedures, particularly if it runs par- The liver produces bile continuously and excretes it into the
allel to the cystic duct or in the mesentery of the gallbladder. The bile canaliculi. Bile leaves the liver through the right and left
cystic artery arises from the right hepatic artery in about 90% of hepatic ducts, into the common hepatic duct and then the com-
cases, but it may arise from the left hepatic, common hepatic, mon bile duct. With an intact sphincter of Oddi, tonic contrac-
gastroduodenal, or superior mesenteric arteries (Fig. 32-5).3 tion diverts bile flow into the gallbladder for storage, while
mealtime stimulation allows for its passage into the duode-
num. The normal adult consuming an average diet produces
500 to 1000 mL of bile a day. The secretion of bile is respon-
sive to neurogenic, hormonal, and chemical stimuli. Parasym-
pathetic stimulation from the hepatic branches of the vagus
nerve increases secretion of bile, whereas sympathetic nerve
stimulation via the celiac plexus results in decreased bile flow.
Hydrochloric acid, partly digested proteins, and fatty acids
entering the duodenum from the stomach after a meal stimulate
the release of secretin from the S-cells of the duodenum, and
increases bile production and flow.
Bile is mainly composed of water, mixed with bile salts
and acids, cholesterol, phospholipids (lecithin), proteins, and
Figure 32-4. Floating gallbladder suspended on mesentery bilirubin. It also contains several minor components such as