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Page 6 of 15 Kato et al. Hepatoma Res 2021;7:10 I http://dx.doi.org/10.20517/2394-5079.2020.129

method using Maryland forceps or direct parenchymal division using monopolar scissors or ultrasonic
shears (Harmonic ACE Curved Shears, Intuitive Surgical). Small vessels were divided using ultrasonic
shears, small metal clips, or monopolar scissors, and large vessels were divided using ligature clips or linear
stapler.

At our institution, there are two basic approaches to AR: the extrahepatic Glissonian pedicle approach
(GPA) and hepatic vein (HV) root-at first one-way resection, regardless of the type of anatomic
hepatectomy [14-16] . Using our method of AR, on the basis of the extrahepatic GPA, the target Glissonian
pedicles corresponding to the anatomic liver area to be resected are isolated and occluded or divided at
the hepatic hilum before parenchymal dissection is started [14-16] . This approach to the hilar Glissonian
pedicles is based on the anatomical relationship between Laennec’s capsule of the liver and the Glissonian
sheath [14-16] . Both structures can be manually separated from each other at the hilum by careful dissection.
On the other hand, for AR requiring exposure of the major HVs, we used a technique called the HV root-
at first one-way resection [15,16] . During this approach, we first dissect and expose the roots of the major HVs
as a regular procedure, followed by cranial-to-caudal one-way parenchymal dissection after occlusion of
the target Glissonian pedicles. This approach to the major HVs is also based on the anatomical background
[14]
of Laennec’s capsule .
During all types of robotic AR performed in this series, we applied the extrahepatic GPA and HV root-
at first one-way resection as standardized procedures; both approaches were similar to those used for
conventional laparoscopic AR [15,16] . Even in anatomic segmentomies (n = 7) or subsegmentectomies (n = 6;
subsegment VIII-c: n = 3, VIII-acd: n = 1, IV-a: n = 1, VI-a: n = 1), we isolated and controlled the third- or
fourth- order pedicles extrahepatically at the hilum, before starting parenchymal dissection.

We used intraoperative ultrasonography for detection of tumors, acquisition of resection margin and
confirmation of vascular anatomy and flow. In the early period of this study, we used conventional
laparoscopic ultrasonography, which was operated by the assistant surgeon. In the later period, a dedicated
probe was used directly by the console surgeon.

The use of the Pringle maneuver was restricted to cases where bleeding during parenchymal dissection
was not controlled well. When the Pringle maneuver was applied, we snared the hepatoduodenal ligament
using a tape and tourniquet it with a Nelaton catheter, which was brought out through the abdominal wall
along with the tape inside it.

Representative procedures during robotic AR: robotic anatomic segmentectomy VIII
Robotic AR procedures that are used in robotic anatomic segmentectomy VIII are shown in Figures 2-4.
Cystic plate cholecystectomy [14,16] is the first procedure; it allows good access to the root of the Glissonian
pedicle of the anterior section (G-ant). At the hilar plate, several pieces of fibrous tissue connect the plate
[14]
and liver parenchyma, which we call the anchor . By dividing the anchors, one can easily create and enter
[14]
the space between the liver parenchyma covered with Laennec’s capsule and Glissonian pedicle sheaths .
[14]
Laennec’s capsule-based layer dissection at Gates IV and V according to the Gate theory facilitates
extrahepatic isolation of the G-ant by passing a tape from Gate IV to Gate V [Figure 2A and B]. Compared
to the open procedure, laparoscopic and robotic approaches seem to be more useful for meticulous
and accurate layer dissection and isolation of pedicles due to the magnified caudal view of the hilum.
Furthermore, during robotic dissection of the hilar pedicles, articulated instruments are quite useful.

Next, the ventral surface of the G-ant is dissected, and the pedicle of segment V (G-V) is isolated
extrahepatically. The right stump of the tape holding G-ant is then passed under G-V and switched
cranially over G-V, resulting in the isolation of the G-VIII pedicle (G-VIII) extrahepatically [Figure 2C].