**1. Introduction**

Hepatic resection is the gold standard treatment for some of the most common malignant tumours of the liver, including primary tumours (hepatocellular carcinoma and cholangiocarcinoma) and colorectal liver metastasis and it can be sometimes the treatment option for some benign tumours [1]. Hepatobiliary surgery also includes complex biliary interventions for benign and malignant pathologies that, in addition to the liver resection, may require biliary reconstructions and bilioenteric anastomosis [2].

Open surgery remains the predominant approach for most of these hepatobiliary procedures. However, there is an exponential increase of minimally invasive surgery (MIS) within this field, supported by large cases series and randomised control trials (RCTs) recently published in the literature [3].

Outcomes from the available literature suggests that MIS for liver resections improves patients' outcomes in terms of length of stay, blood loss and postoperative complications. Although some series suggest longer operative time and higher initial costs, the overall cost-efficiency seems to favour laparoscopic surgery [4, 5]. Despite this data, laparoscopic liver surgery is not routinely performed in all Hepatobiliary Centres and there is a large proportion of patients being treated via open approach. The delayed implementation of this type of intervention is commonly related to the technical challenges of these operations, the long tradition of open surgery associated to liver transplantation and the specific technological requirements attached to this type of resections.

From the original era of the pioneers in laparoscopic surgery, the consensus meetings in Louisville and Morikawa highlighted the challenges of this new approach. Recommendations from these meetings were very cautious about suggesting laparoscopic liver surgery for every patient and limited its clear indication to minor resections. From them, MIS for minor liver resections (less than 3 segments) such as left lateral secitonectomy and segmentectomies from the anterior Couinaud segments (II to VI) became well established [6]. On the contrary, there has been limited diffusion of minimally invasive major hepatectomies and it is commonly confined to high volume specialised centres [7]. This is in part due to the more complex anatomical and technical challenges of major hepatic resections, and the inherent limitations of laparoscopic surgery.

Traditional laparoscopic surgery is the most commonly used MIS technique for liver resections whilst there is also an increment in the number of series of robotic liver surgery [8]. Advantages of robotic surgery when compared to traditional laparoscopic surgery are well described and include: a magnified three dimensional (3D) view, tremor filtration and improved dexterity with articulated instruments providing seven degrees of freedom [9]. It also adds some surgeon's specific advantages in terms of ergonomics with the suggested, but not proven, potential reduction of fatigue, increase precision and longer work expectancy. However controversies around robotic surgery remain when compared with laparoscopic surgery. Main limitation was always the higher cost without any evidence suggesting clinical superiority when compared to laparoscopic surgery. There is, in fact to date, lack of agreement whether they should be compared against each other, or directly compared to open surgery. We are of the opinion that both should be grouped as MIS and promoted equally for the benefit of the patient.

In this chapter we describe the key aspects of robotic hepatobiliary surgery, with a focus on technical descriptions, the current evidence base, limitations, and possible future developments.
