This was a retrospective study on consecutive patients with liver haemangioma who underwent hemihepatectomy from April 2011 to April 2017 in our hospital. The diagnosis of giant liver haemangioma was made by computed tomography and/or magnetic resonance imaging and postoperative histopathology (Fig. 1). The main indication for operation was a giant liver haemangioma (>10 cm in diameter) with symptoms (abdominal pain, nausea, or premature satiety after a meal). These patients were all suitable for undergoing robotic, laparoscopic and open hemihepatectomy. The choice of operation was determined by the patient after discussion with the operating surgeons. All the operations were carried out by a single team of experienced liver surgeons. The variables selected for analysis were age, sex, tumour size, tumour location, hepatic disease, operative time, intraoperative blood loss, rate of blood transfusion, postoperative hospital stay, time to oral intake, time to get-out-of-bed, liver function after 24 hours of surgery, visual analogue scale (VAS) score after 24 hours of surgery, and operative morbidity/mortality. According to the type of operation, the patients were divided into the robotic hemihepatectomy (RH) group, laparoscopic hemihepatectomy (LH) group, and open hemihepatectomy (OH) group. Comparisons of the variables were then made among the three groups. The medical history was taken and physical examination and liver ultrasonography were routinely carried out at a follow-up visit 3 months after surgery. The data in our study that came from a single study centre were acquired retrospectively. As we know, potential biases naturally exist in respective studies. However, we developed a rigorous and scientific search strategy to lower the power of this bias (Fig. 2). This study was approved in writing by the Beijing Special Clinical Application Program (Grant No. Z171100001017239 and Grant No. Z151100004015004).
Measurements of liver volumes
The volumes of the future liver remnant (FLR) and liver haemangioma were calculated based on computed tomographic (CT) volumetry. The CT data were transferred to a workstation for assessment. Liver volumes were calculated by the integrated software technique. A standard liver volume (SLV) was calculated using the following formula: liver volume (cm3) = 706 × body surface area (m2) + 2.4. This volume has been validated in a meta-analysis to be a precise and unbiased method to estimate total liver volume . The ratio of FLR volume to total liver volume was estimated using the following formula: FLR/SLV. The body surface area (BSA) was calculated using the following formula: body surface area (m2) = [body weight (kg) × body height (cm) ÷ 3,600]0.5.  The resected volume was calculated using the following formula: resected volume (cm3) = standard liver volume (cm3) - future liver remnant volume (cm3). The resected normal liver volume was calculated using the following formula: resected normal liver volume (cm3) = resected volume (cm3) - liver haemangioma volume (cm3). The ratio of resected normal liver volume to resected volume was estimated using the following formula: resected normal liver volume/resected volume.
The patient was placed in a modified lithotomy and reverse Trendelenburg position, with the first assistant standing between the patient’s legs. For right hemihepatectomy, after general anaesthesia with endotracheal intubation, the first trocar was inserted at the umbilical site after creating pneumoperitoneum. Intraabdominal pressure was controlled at 12 to 14 mm Hg (1 mm Hg=0.133 kPa). The robotic camera was inserted through the umbilical port, and the other four ports were introduced under laparoscopic view. The camera port was then placed in the right paraumbilical area. The first and second robotic arm ports were introduced in the left and right upper quadrant areas, respectively. The umbilical port was used as the assistant’s port. The third robotic arm port was introduced at the left anterior axillary line (Fig. 3). For left hemihepatectomy, port placement was similar to that of right hemihepatectomy, except that the placements of the camera port and the assistant’s port were swapped. Selective hemihepatic inflow occlusion was used. The modified Pringle’s manoeuvre was used to occlude inflow of the entire liver when necessary (Fig. 4). Liver parenchymal transection was performed using an ultrasound scalpel. Intraparenchymal control of major vessels was achieved with clips or sutures (Figs. 5, 6). The corresponding hepatic pedicle and hepatic vein were transected with a linear vascular endo-stapler. The resected specimen was placed in a specimen bag and retrieved from the abdomen through an extension of the umbilical port wound.
The patient was placed in a supine position with the patient’s legs abducted. The surgeon stood between the patient’s legs, and the first assistant stood on the right side of the patient. After general anaesthesia with endotracheal intubation, the first trocar was inserted into the umbilical site after creating pneumoperitoneum. Intraabdominal pressure was controlled at 12 to 14 mm Hg (1 mm Hg=0.133 KPa). Four ports were usually used. The operating ports were placed in a fan shape around the lesion. Selective hemihepatic inflow occlusion was used for hemihepatectomy. The modified Pringle’s manoeuvre was used to occlude the inflow to the entire liver when necessary. Liver parenchymal transection was performed using an ultrasound scalpel. Intraparenchymal control of major vessels was achieved with clips or sutures. The corresponding hepatic pedicle and hepatic vein were transected using a linear vascular endo-stapler. The resected specimen was placed in a specimen bag and retrieved from the abdomen through an extension of the umbilical port wound.
The patient was placed in a supine position. After general anaesthesia with endotracheal intubation, laparotomy was carried out via a right subcostal incision. After exploration of the abdominal cavity, hepatic vascular inflow occlusion was similar to the technique used in laparoscopic hemihepatectomy. Liver parenchymal transection was performed using an electrotome or ultrasound scalpel. Haemostasis was achieved with monopolar cautery, sutures, or clips.
Qualitative variables were compared using the chi-square test. The likelihood ratio test was used for data when the theoretical frequency was less than 5. The data are expressed as the mean ± standard deviation. Continuous variables were compared using ANOVA. If ANOVA indicated that there were differences between the three groups, the SNK (Student-Newman-Keuls) test was used for further verification. A P-value of <0.05 was considered to be statistically significant. Statistical analyses were performed using SPSS software (version 19.0, IBM Corp, Armonk, NY). The study was reported following the STROCSS criteria.