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Nota et al. Mini-invasive Surg 2020;4:74 I http://dx.doi.org/10.20517/2574-1225.2020.57 Page 7 of 9

Table 4. Summarized comparison of robotic liver resection with conventional laparoscopic liver resection
Minor resections, Operative time, Blood loss, median Conversion, Major complications, Mortality,
Approach n
n (%) mean (SD), min (IQR), mL n (%) n (%) n (%)
Conventional 885 683 (77)* 164 (95) 200 (50-500) 121 (14) 76 (9) ^ 9 (1)
laparoscopy
Robotic liver 70 60 (86) 160 (78) 150 (40-300) 5 (7) 10 (14) 1 (1)
resection
*Defined as less than three liver segments in Dutch LAELIVE database; ^defined using the Accordion severity grading system of surgical
complications. SD: standard deviation; IQR: interquartile range

for pancreatoduodenectomy, whilst the number of conventional laparoscopic pancreatoduodenectomies
[19]
performed decreased . This finding supports the hypothesis that robotic surgery might be better suited
(and more widely implemented) than conventional laparoscopy for complex procedures, such as pancreatic
resection or liver resection.

Since the use of robotic technology in liver resection is gaining momentum, new techniques and devices for
parenchymal transection have emerged. Initial series on robotic liver resection mostly reported the use of
the robotic Harmonic Scalpel or the Maryland Bipolar Forceps for transection of the parenchyma . Other
[7]
currently available devices include the PK Dissecting Forceps (Intuitive Surgical, Sunnyvale, California,
USA), EndoClips, robotic stapler, and the Vessel Sealer . The Harmonic Scalpel, however, lacks the ability
[20]
to articulate. The Maryland Bipolar Forceps and the PK Dissecting Forceps provide meticulous dissection,
but these instruments appear inefficient for larger transection planes. EndoClips provide reliable ligation of
vessels and bile ducts, though do not seem efficient for larger transection planes. Robotic staplers facilitate
reliable sealing, but are expensive. A few cases using the Vessel Sealer for transection of the parenchyma
[21]
during robotic liver resection have been reported by Kingham et al. , however, no separate outcomes were
reported for the different transection techniques used in this study.

The results in our study demonstrate that the use of the Vessel Sealer is feasible and safe during robotic
liver resection. Only ten patients (14%) suffered from a major complication, from which one patient died.
However, this patient suffered from post hepatectomy liver failure, which is most likely a consequence of
the extent of the resection rather than of the parenchymal transection technique chosen. Three patients
(4%) suffered postoperatively from bile leakage, which is comparable to large series reporting on open
and laparoscopic liver resection [22-25] . We could generally employ the Vessel Sealer for parenchymal bile
ducts, portal branches and veins but use a stapler and/or hemolocks for inflow/outflow pedicles, major
veins, or when larger vascular structures are encountered that are clearly beyond a size that could easily
be sealed with a margin within the length of sealer’s surface at 90 degrees. We therefore conclude that the
Vessel Sealer is appropriate to seal most vascular structures encountered within the parenchyma of the
liver segments. The R1 resection rate in our series (defined as a surgical margin of < 1 mm) appears to be
relatively high (24%). However, studies show that R1 resection for colorectal liver metastases (CLRM) can
be considered acceptable [26,27] . The majority of our R1 resections were for CLRM. In addition, in our initial
series, robotic manipulation of the liver tissue during resection may have caused inadvertent laceration in
the specimen contributing to the number of R1 margins on final pathology in several cases.

Secondly, we provided an overview of all conventional laparoscopic liver resections performed in the
Netherlands. Our outcomes are not inferior to those of conventional laparoscopic liver resection. Major
morbidity appeared to be lower after conventional laparoscopic liver resection, however, different
definitions were used for the grading of the postoperative complications.

Several limitations must be considered for this study. Firstly, the patients who underwent robotic liver
resection in this study were selected. Patients with tumours adjacent to the hepatic vessels, patients who