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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_1260_Библиотеки_им_академика_М_И_Перельмана
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Figure 10.1 Hepatic division. Couinaud divided the left hemi-
liver into left paramedian and lateral sectors, while Healey and
Schroy divided the left lobe into medial and lateral segments.
Source: Takayama [11]. Reproduced with permission of Wiley.
10.2 Basic liver anatomy
10.2.1 Hepatic division
In the 1950s, Couinaud [2] and Healey and Schroy [10]
independently advocated two nomenclature systems for
hepatic division based on the results of corrosion cast
analyses (Figure 10.1). Both systems are widely accepted
throughout the world, each dividing the liver into three
levels. Couinaud’s levels are (1) hemi-liver, (2) sector,
and (3) segment, while Healey defined the levels as (1)
lobe, (2) segment, and (3) area. The caudate lobe as
defined by Healey corresponds to Couinaud’s segment
I, and Healey subdivided segment IV into the medial
superior and inferior areas [11].
Although there are some inconsistencies between the
two systems, surgeons have used either or both in their
clinical practice. However, Couinaud’s nomenclature,
based on the intrahepatic portal and hepatic venous
system, is more widely accepted in liver surgery today.
In Couinaud’s nomenclature, the liver is divided into
right and left hemi-liver along the middle hepatic vein
(MHV) (corresponding to the RexCantlie line). Each
hemi-liver is subdivided into two sectors by the right
hepatic vein (RHV) and left hepatic vein (LHV) (right/
left lateral and paramedian sectors), respectively. Each
sector (excluding the left lateral sector) is further subdivided into two segments, so that the overall number of
Relevant hepatobiliary anatomy 149
segments for the total liver is an eight-segment subdivision, including the caudate lobe (segments IVIII),
according to the third-order branches of the intrahepatic
portal pedicles. The liver segments are denoted in a
clockwise fashion by Roman numerals, starting from
the caudate lobe as segment I. Interestingly, this clockwise
designation is numbered similarly to the administrative
districts (arrondisements) of Paris.
In Healey’s nomenclature, Couinaud’s hemi-livers correspond to lobes, sectors become segments, and segments
become areas. The conceptual difference between the two
nomenclature systems lies in the left side of the liver.
Couinaud divided the left portal vein into an umbilical
portion and a segment II branch. Consequently, the left
hemi-liver was divided into the left paramedian sector
(Couinaud’s segments III and IV) and the lateral sector
(segmentII). Healey divided the left hepaticartery and bile
duct into lateral and medial branches, causing the left lobe
to be divided into the lateral segment (segments II and III)
and the medial segment (segment IV). The fact that the
term “segment” is used in both concepts, but indicates
different parts of the liver, has created confusion [11].
From an embryological perspective, Couinaud’s division
is more accurate than Healey’s [12]. In human embryos
(Figure 10.2), the right and left hemi-livers emerge simultaneously, and the umbilical vein connects equally to the
right and left portal veins. In the fifth week of gestation, the
umbilical vein feeding the right liver obliterates while the
vein feeding the left liver remains. This leads to an increase
in the left liver volume. On closure of the umbilical vein
after birth, the left liver gradually shrinks, triggering growth
of the right liver. This process of development indicates that
the right and left livers fundamentally share the same
formation pathway and anatomy.
In Couinaud’sdefinition, the right and left lateral
sectors share the same anatomical features of receiving
the first major branch from the right and left portal veins,
of having a main hepatic vein at their medial sides, and of
having a main portal pedicle at the center of the territory.
Therefore, treating segment IV as an independent sector,
as suggested by those who prefer the Healey nomenclature, primarily American surgeons, could be considered
to be anatomically inaccurate. As we are striving for
greater accuracy, it is believed by many that the use of
the Healey nomenclature to describe anatomical landmarks of the liver should be abandoned.
From a surgical viewpoint, a left paramedian sectoriectomy (e.g. segment III and IV) [13] can be performed
150 Chapter 10
Figure 10.2 Liver development. (a) the umbilical veins (UV) enter both the right and left portal veins (PV); (b) the right UV
obliterates, and the left UV remains; (c) the left UV closes and becomes the round ligament (RL) together with Arantius’ ligament
(AL). IVC, inferior vena cava; LB, lateral branch; PB, paramedian branch. Source: Makuuchi [12]. Reproduced with permission of
Lippincott, Williams & Wilkins.
similarly to a ri ght paramedian sectoriectomy (e.g.
resection of segments V and VIII) [14], with the LHV
or RHV running on the resected surface. In practice,
however, surgeons’ preference and a greater relevance
for the encountered clinical scenar ios mean that lateral
(e.g. segment II and III) or medial segmentectomy
(segmentectomy IV) is routinely performed in cli nical
practice today. Recently, the Hjortsjo’s divi sion of the
right paramedian sector into the ventral a nd dorsal
segments, which is clinically highly relevant, has
been proposed [15,16].
In 2000, a committee of the International HepatoPancreatico-Biliary Association proposed the first universal terminology for liver anatomy and resection (the
Brisbane 2000 Nomenclature) [17]. This classification
system aimed to simplify the descriptions of different
types of resections according to anatomically relevant
structures. In this system, the anatomical terms for parts
of the liver (hemi-liver, section, and segment) correspond
to the terms used to describe hepatic resection (hemihepatectomy, sectionectomy, and segmentectomy),
using Couinaud’s segmental reference as the preferential
anatomical source reference (segments IVIII). The
watersheds for the first-order, second-order, and thirdorder divisions are referred to as the midplane, the right
and left intersectional planes, and the intersegmental
planes, respectively. As a result, the Brisbane system is
based on the anatomy described by Couinaud but changes
the terminology (from sector to section), except for division of the left liver, and defines en bloc resection of
segments II and III as a lateral sectionectomy [18].
Recently, Strasberg [19] evaluated the global dissemination of the terminology 10 years after its introduction and
found that use of the Brisbane terms “hemihepatectomy”
and “sectionectomy” has increased dramatically in comparison with the discarded term “lobectomy,” especially
in America and Asia.
10.2.2 Portal vein
Of the vessels related to the liver, the portal venous system is
the most easily identifiable on imaging and is therefore a
good surgical landmark. The first-order branches of the
portal vein include the right and left main branches; the
second-order branches include the right anterior and posterior sectoral branches, left umbilical branch, and caudate
(segment I) branch; and the third-order branches include
thesegmental (segments II–VIII)branches(Figure 10.3) [20].
Third-order branches are named after the major f eeding area in the segmental domain (i.e. P8v is the Portal
pedicle of segment VIII for the ventral portion) [3,11].
Portalmapping facilitatesthesurgeon’sunderstandingof
the segmental anatomy in each patient; all portal venous
branches and hepatic veins can be traced by ultrasound
mapping of the portal venous branches. In addition to
mapping intrahepatic vessels, a precise understanding of
the relationship between target tumor and related intrahepatic vessels is of critical surgical importance, especially
when anatomical segmentectomies are performed [21].
10.2.3 Hepatic vein
The hepatic venous system consists of the three main
hepatic veins (RHV, MHV, and LHV), which run along
the right, main, and left portal fissures, respectively
(Figure 10.4). In addition, the umbilical fissure vein
runs along the umbilical fissure between the LHV and
MHV, and the anterior fissure vein runs along the anterior
fissure between the MHV and RHV. The drainage of these
veinshas several possible variations, in whichthe umbilical
Relevant hepatobiliary anatomy 151
Figure 10.3 Portal venous system. (a) anterior view; (b) lateral view of the liver. P represents the portal venous branch, numbers
refer to the eight segments of the liver, and lower-case letters refer to the segmental branches named after their major feeding
portions in the segment (v, ventral portion; d, dorsal portion; l, lateral portion; s, superior portion; i, inferior portion).
Source: Takayama [11]. Reproduced with permission of Wiley.
152 Chapter 10
Figure 10.3 (Continued)
Relevant hepatobiliary anatomy 153
Figure 10.4 Hepatic venous system. The liver has three major hepatic veins (right hepatic vein, RHV; middle hepatic vein, MHV;
left hepatic vein, LHV) and two fissure veins (umbilical fissure vein, UFV; anterior fissure vein, AFV). i-RHV, inferior RHV;
SV, superficial vein; V1, venous branch of segment I.
154 Chapter 10
fissure vein joins the LHV (90%), the MHV (7%) or the
bifurcation of both veins (3%). Likewise, the junctures of
the anteriorfissurevein may includea junctureat the MHV
(91%), RHV or inferior vena cava (IVC) (9%). There are
accessoryveins, such as the inferior RHV draining segment
VI and the short hepatic vein draining segment I [22].
The hepatic veins are a crucial element that must be
understood in order to perform anatomical liver resection
and partial liver transplantation. The major hepatic veins
represent a good landmark in resection and are, when
damaged or resected, a source of congestion and subsequent atrophy of the graft.
10.3 Anatomy for hemihepatectomy
10.3.1 Hilar vessels and hepatic vein
The hepatic hilus consists of the hilar plate above the hepatic
confluence, portal vein, hepatic artery, and bile duct (Figure
10.5). The umbilical portion of the left portal vein is located
at the left distal end of the hilus, and the gallbladder covers
the right distal end of the hilus with serosa [23].
The portal vein runs along the right back side of the
proper hepatic artery and the back side of the
hepatoduodenal ligament. The right portal vein usually
bifurcates into anterior and posterior branches at Rouviere’s sulcus. The left hepatic artery enters the liver
through the left part of Rex’s recessus, and the right
hepatic artery bifurcates into an anterior branch which
runs between the bile duct and the portal vein, and a
posterior branch which runs caudally and enters the liver.
The left bile duct is formed just above the left portal vein
by the junction of the medial and lateral ducts. The right
anterior bile duct lies on the right anterior portal vein and
comes down to join with the right posterior bile duct [23].
10.3.1.1 Portal vein
At the hepatic hilus, the main portal trunk bifurcates into
left and right portal veins. The left portal vein runs
horizontally and then vertically with formation of the
umbilical portion after giving off the portal vein branch to
segment II (P2). A few branches run dorsally from the
horizontal portion of the left portal vein to the caudate
lobe. In contrast, the right portal vein has three ramification patterns (Figure 10.6):
• common type (86%), forming a long right portal vein
• posterior type (7%), in which the posterior branch
arises directly from the main portal trunk
• trifurcation type (6%), in which the left, anterior, and
posterior branches arise from the same point [24].
Figure 10.5 Hepatic hilus. The hepatic hilus is made of the hilar
plate, including three vessels. Numbers refer to Couinaud’s
segments. BD, bile duct; LHA, left hepatic artery; MHA, middle
hepatic artery; PV, portal vein; RHA, right hepatic artery.
10.3.1.2 Hepatic artery
The ramification of the hepatic artery is classified into five
patterns, including (i) common type (76%); (ii) replaced
left hepatic artery (12%)arising from the left gastricartery;
and (iii) replaced right hepatic artery (11%) originating
from the superior mesenteric artery (Figure 10.7) [25]. In
patients with the third pattern, surgeons need to be careful
when the right (or posterior) hepatic artery runs behind
the portal trunk, especially when performing a right hemihepatectomy. The frequency of a type (iv) pattern with
double replaced left and right hepatic arteries arising from
the left gastric and superior mesenteric arteries, and type
(v), with replacedcommon hepaticarterydevelopingas an
independent branch of the superior mesenteric artery, is
very low.
10.3.1.3 Bile duct
The bile duct in the right hemi-liver is classified into three
types: (i) supraportal type (71%), in which the right
posterior duct runs behind the portal vein and joins the
anterior duct at the cranial side; (ii) supraportal type
Relevant hepatobiliary anatomy 155
Figure 10.6 Portal vein anatomy. The portal vein (PV) has three ramification patterns: (a) common (86%), (b) posterior (7%), and
(c) trifurcation (6%). Ant PV, anterior PV; LPV, left PV; Post PV, posterior PV; RPV, right PV.
joining left duct (17%), in which the right posterior duct
directly enters the left hepatic duct; and (iii) infraportal
duct prior to surgery can be very helpful to the surgeon
to avoid injury at the level of the hilus (Figure 10.9).
type (12%), in which the right posterior duct runs caudal
to the portal vein and joins the anterior duct at the caudal
side (Figure 10.8) [26]. As for the bile duct in the left
hemi-liver, there are three types: (i) B2/B3 common type
(50%), in which B2 and B3 join to the left of the umbilical
portion to form the common duct, which is joined by B4;
(ii) B3/B4 common type (29%), in which B3 and B4 join
to the right of the umbilical portion, which is joined by B2;
and (iii) confluence type (13%), in which B2, B3, and B4
join at the same point [27]. The relationship between
bile ducts and portal veins can be confusing, because
the bile ducts and portal veins do not run parallel at
the hepatic hilus. Therefore, three-dimensional (3D)
computed tomography (CT) reconstruction images at
the confluence of the posterior bile duct or left segmental
10.3.1.4 Hepatic vein
In hemihepatectomy, surgeons have to understand the
precise anatomy of tributaries of the MHV because in true
anatomical resection, the trunk needs to be exposed on
the resected surface (Figure 10.10). The MHV has three
distinct venous branches draining the anterior segment:
V5v (for ventral segment V), V8v (for ventral segment
VIII), and the anterior fissure vein. The MHV has two
venous branches draining segment IV: V4a (for inferior
segment IV) and V4b (for superior segment IV). V5v joins
V4a and forms the main trunk of MHV, and V8v and V4b
join MHV at the terminal portion. The anterior fissure
vein usually joins the MHV but sometimes joins the RHV
(6%) or IVC (2%). On the other hand, V4b joins the LHV
156 Chapter 10
Figure 10.7 Hepatic artery anatomy. The hepatic artery has three branching patterns. (a) Common (76%). (b) Replaced left hepatic
artery (LHA) (12%). (c) Replaced right hepatic artery (RHA) (11%). CA, celiac axis; LGA, left gastric artery; post HA, posterior HA;
SMA, superior mesenteric artery.
(57%) or MHV (43%) [22]. Accessory hepatic veins such
as the inferior RHV draining segment VI can be present
(27%), requiring that surgeons exercise caution in mobilization of the right hemi-liver.
In hemihepatectomy by an anterior approach using a
hanging maneuver [28], surgeons insert a pair of forceps
into the potential space between the retrohepatic IVC and
the liver. To identify a longitudinal avascular virtual
plane, Hirai et al. [29] have defined three insertion
courses: rightward, intermediate, and leftward. They
recommend that in patients without an inferior RHV,
the rightward course is the best approach, less frequently
damaging the caudate vein. However, changing from a
leftward to rightward approach to the retrohepatic space
is required in patients with an inferior RHV.
10.3.2 Pericaval ligament
10.3.2.1 Inferior vena cava ligament
This ligament is a fibrous membrane around the IVC
and attaches to the RHV and LHV at the cranial end.
Division makes it possible to expose the insertions of
the RHV and LHV to the IVC [30]. The attachment
between the ligament and IVC is usually loose, and its
mean length and width are 17 mm and 15 mm, respectively [31]. Therefore, when s eparating the IVC ligament, it is easier and safer to insert the forceps from the
caudal to cranial side. The lymphatic vessels in the
ligament are abundant and should be ligated and
divided to prevent postoperative lymphorrhea, especially in patients who have cirrhosis or those undergoing liver transplantation.
Relevant hepatobiliary anatomy 157
Figure 10.8 Bile duct anatomy. The right bile duct (BD) has three joining patterns: (a) supraportal (71%), (b) supraportal joining left
duct (17%), and (c) infraportal (12%); and the left BD has three: (d) B2/B3 common (50%), (e) B3/B4 common (29%), and
(f) confluence (13%).
10.3.2.2 Arantius’ ligament
During the embryonic period, this ligament is a bypass
between the umbilical portion of the left portal vein and
the IVC and runs from the ventral side of the umbilical
portion to the confluence of the LHV into the IVC (or
directly connects to the IVC). The round ligament, umbilical portion, and Arantius’ ligament line up on a straight
line. Arantius’ ligament is on the fossa between the left
side of the caudate lobe and the left hemi-liver (fossa
ductus venosi) and is attached to the surface of the liver.
158 Chapter 10
Figure 10.9 Three-dimensional image of the bile duct: (a) bile duct image and (b) bile duct with portal vein image. B3 and B4 form a
common duct (B3/B4 common type), and then B2 joins (a) at the right side of the umbilical portion (UP) (b). The right anterior and
posterior bile ducts join (a) at the ventro-cranial point of the right portal vein (supraportal type) (b).
Arantius’ ligament can be found as a band structure on
the anterior surface of the caudate lobe, and its junctions
must be divided to mobilize the caudate lobe.
10.3.3 Landmarks for surgeons
In hemihepatectomies, hepatic parenchymal transection [32] should be carried out along the demarcation
line, which can be obtained by extrahepatic ligation of the
hepatic artery and portal vein. To minimize hemorrhage
and avoid transfusion [33] during transection it is important to confirm the branches of the MHV preoperatively,
for which 3D imaging modalities such as CT-based simulation are useful [34].
Figure 10.10 Hepatic vein anatomy. The middle hepatic vein
has five distinct branches, including the vein for ventral
segment V (V5v), the vein for ventral segment VIII (V8v), the
anterior fissure vein (AFV), the vein for inferior segment IV
(V4a), and the vein for superior segment IV (V4b). V8d, vein
for dorsal segment VIII.
10.3.3.1 Right hemihepatectomy
Anatomical resection requires complete exposure of the
MHV, running along the midplane of the liver (Figure
10.11). At the initial stage of transection, the surgeon will
seek and trace the tributary of the MHV (V5v) to reach the
trunk of the MHV. Transection advances cranially with
division of other tributaries (V8v, AFV) up to the caval
insertion. At the hepatic hilum, the surgeon must be
aware of the ramification pattern of the vessels to prevent
injury to the anomalous hepatic artery and bile duct.
10.3.3.2 Left hemihepatectomy
Since the surgical landmark is again the MHV (Figure
10.12), the surgeon will trace the tributary of the MHV
(V4a) to reach the trunk of the MHV. Transection advances cranially with division of other tributaries (V4b, occasionally the umbilical fissure vein) up to the caval
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