Similar to other surgical techniques, minimally invasive techniques have gained popularity for liver resection in recent years. This has also been observed in donor hepatectomies for living-donor liver transplantation. Minimally invasive hepatectomy can range from laparoscopy-assisted procedures to pure laparoscopic donor hepatectomy, in which the entire surgical procedure is performed using laparoscopic techniques, depending on the extent of laparoscopic technique used in the overall procedure. Following the first reported case of pure laparoscopic donor left lateral sectionectomy in 2002 [1], international consensus guidelines have been updated [2-5]. The latest guidelines state that this technique is applicable and should be considered standard practice for experienced surgical teams [5]. According to these guidelines, full left liver grafts are suitable for pure laparoscopic donor hepatectomy (PLDH). However, the guidelines indicate that pure laparoscopic donor right hepatectomy (PLDRH) should be reserved for selected cases [5]. The selection criteria for PLDRH may vary across centers based on their experience and policies. Generally, variations in the vasculature or biliary system are key selection criteria [2-5]. Additionally, high graft weight has been reported to be another important factor in the selection process [6].

Our center initiated PLDH in November 2015, and by December 2022, we had performed PLDH, mostly PLDRH, in more than 650 cases. With the use of a three-dimensional flexible scope and indocyanine green fluorescence camera, no selection criteria had been defined since March 2016. In our previous reports, we demonstrated the feasibility and safety of PLDRH in cases with variations in the bile duct or portal vein [7-10]. Our findings suggest that these variations should not be considered as contraindications for the procedure. We also reported that high body mass index (BMI) and graft weight (>1,000 g) should not be considered contraindications for PLDRH [11,12]. However, a previous study included only 10 cases of PLDRH with a graft weighing >1,000 g. Therefore, this study aimed to determine the possibility and safety of performing PLDRH on large liver grafts weighing >1,000 g by analyzing multiple cases.

This study was approved by the institutional review board (IRB) of Seoul National University Hospital (IRB No. H-2302-038-1402). We retrospectively reviewed the medical records of PLDRH cases in which the graft weight exceeded 1,000 g, between November 2015 and December 2021. Because this study was conducted retrospectively, the need for obtaining informed consent was waived. According to the Clavien classification [13], major complications were defined as those of grade III or higher. In addition, we divided the postoperative complication period into early and late stages, with complications occurring within 30 days postoperatively. The warm ischemic time was defined as the time between ligation of the right hepatic artery and liver removal.

Statistical Analysis

The results are presented as either numbers and percentages or medians and ranges, depending on the appropriateness of each parameter. Spearman’s correlation analysis was used to assess the correlation between the operative time and cumulative experience. In all analyses, a p-value of less than 0.05 was considered statistically significant. All data were analyzed using the IBM SPSS Statistics 23.0 (IBM Corp.).

Twenty cases of PLDRH were identified, in which the graft weight exceeded 1,000 g. Table 1 summarizes the baseline characteristics and postoperative outcomes of the donors included in the study. The study population consisted entirely of male donors, with a median age of 35.0 years, a median BMI of 28.5 kg/m², and an estimated remnant liver volume of 32.8%. The median operative time, time to liver removal, and estimated blood loss were 322.5 minutes, 229.0 minutes, and 325.0 mL, respectively. Fig. 1 demonstrates the changes in the operative time (Fig. 1A) and warm ischemic time (Fig. 1B) with the increase in the number of PLDRH cases with a graft weighing greater than 1,000 g. Although statistically insignificant (Spearman’s rho=—0.147, p=0.364), there was a slight trend towards a decreased total operative time with an increase in the number of cases. However, warm ischemic time significantly decreased as the number of cases increased (Rho=—0.491, p=0.028). We found that the median actual graft weight was 1,042.5 g and the graft-to-recipient weight ratio was 1.7. Four cases (20.0%) required separate anastomoses for grafts with multiple portal vein openings, whereas three (15.0%) required separate anastomoses for grafts with multiple bile duct openings. The median duration of hospital stay for donors was 7.0 days, and only two cases of grade I complications were reported. One donor experienced a wound complication, while the other developed temporary hyperbilirubinemia. Additionally, two cases of grade II complications were identified. One donor was found to have a partial portal thrombus during routine postoperative computed tomography at 1 week, which was managed using temporary low-molecular-weight heparin, followed by temporary aspirin administration. Another donor developed postoperative ileus, which was treated conservatively. No complications rated grade III or higher were observed.

Table 1 .. Donor characteristics, operative outcomes, and postoperative hospital stay.

Variables	Total (N=20)
Male, n (%)	20 (100)
Age, (yrs)	35.0 (21.0–51.0)
ABO compatibility, n (%)
Identical	13 (65.0)
Compatible	4 (20.0)
Incompatible	3 (15.0)
Relationship, n (%)
Son	14 (70.0)
Father	1 (5.0)
Brother	3 (15.0)
Other	2 (10.0)
Body mass index, (kg/m2)	28.5 (22.6–37.0)
Inclusion of middle hepatic vein, n (%)	1 (5.0)
Estimated remnant live volume, (%)	32.8 (29.5–39.0)
Operative time, (min)	322.5 (193.0–433.0)
Time to liver removal, (min)	229.0 (138.0–330.0)
Warm ischemic time, (min)	15.5 (9.0–25.0)
Estimated blood loss, (mL)	325.0 (30.0–800.0)
Intraoperative transfusion, n (%)	0 (0)
Graft weight, (g)	1042.5 (1004.0–1315.0)
Graft-to-recipient weight ratio (00)	1.7 (1.1–2.4)
Multiple graft openings which required separate anastomosis, n (%)
Portal vein	4 (20.0)
Hepatic artery	1 (5.0)
Bile duct	3 (15.0)
Postoperative blood tests
Hemoglobin
Lowest, (g/dL)	12.7 (9.2–13.9)
Delta, (%)	17.3 (8.6–44.9)
Total bilirubin
Peak, (mg/dL)	4.0 (2.0–12.2)
Delta, (%)	856.3 (357.1–2500.0)
Aspartate aminotransferase
Peak, (IU/L)	205.0 (142.0–473.0)
Delta, (%)	1240.6 (672.0–3538.5)
Alanine transaminase
Peak, (IU/L)	247.5 (139.0–616.0)
Delta, (%)	1084.5 (526.9–2700.0)
Hospital stay, (d)	7.0 (4.0–11.0)
Complication, n (%)
Grade I	2 (10.0)
Grade II	2 (10.0)
Grade III or higher	0 (0)

Values are presented as number (%) or median (range)..

Figure 1. Correlation between (A) operative time and (B) warm ischemic time with the progressive performance of pure laparoscopic donor right hepatectomy in grafts weighing over 1,000 g.

Table 2 summarizes the baseline characteristics and postoperative complications of the recipients. Of the total patients analyzed, 17 (85.0%) were male, with a median age of 57.0 years and BMI of 24.3 kg/m². The median Model for End-stage Liver Disease score was 13.0 and the duration of hospital stay was 16.0 days. Among the patients analyzed, six (30.0%) experienced major complications during the early postoperative period, with the majority being biliary problems. Likewise, there were five cases (25.0%) of major complications during the late postoperative period, with biliary problems being the most common. Of the 20 recipients, four died and one required retransplantation. The 1-, 2-, and 5-year survival rates were 95.0%, 78.4%, and 65.3%, respectively. The cause of death in all four cases was cancer, with three cases of hepatocellular carcinoma recurrence and one case of de novo lung cancer. One recipient required retransplantation owing to alcohol intake, which resulted in hepatic failure 1 year after the first transplantation.

Table 2 .. Baseline characteristics and postoperative details of PLDH recipients according to the graft type.

Variables	Total (N=20)
Male, n (%)	17 (85.0)
Age, (yrs)	57.0 (21.0–73.0)
Body mass index, (kg/m2)	24.3 (17.9–28.3)
Underlying etiology, n (%)
Hepatic B virus	12 (60.0)
Alcoholic	5 (25.0)
Other	3 (15.0)
Hepatocellular carcinoma, n (%)	10 (50.0)
Model for end-stage liver disease score	13.0 (6.4–30.0)
Hospital stay, (d)	16.0 (9.0–34.0)
Early major complications, n (%)	6 (30.0)
Intra-abdominal bleeding	1 (5.0)
Intra-abdominal fluid collection	1 (5.0)
Wound problem	1 (5.0)
Biliary problem	3 (15.0)
Cardiac problem	1 (5.0)
Neurologic problem	1 (5.0)
Late major complications, n (%)	5 (25.0)
Intra-abdominal fluid collection	2 (10.0)
Hepatic vein problem	1 (5.0)
Biliary problem	5 (25.0)

Values are presented as number (%) or median (range). PLDH, pure laparoscopic donor hepatectomy..

As the prevalence of PLDH increased, there was a growing need for international consensus guidelines, which were subsequently developed and continuously updated over time [2-5]. The latest international consensus guidelines state that while PLDH should be considered a standard practice for the left lateral section after the surgical team has undergone sufficient training, it is only applicable to certain right liver grafts [5]. However, it was noted that the selection criteria for PLDRH varied according to the experience of each center. Although some centers strictly adhere to donor criteria, including limiting the graft weight to less than 700 g, ensuring a graft-to-recipient weight ratio greater than 1%, and favorable vascular and biliary anatomy, other centers, including Seoul National University Hospital, do not use any selection criteria. [6,9,10,14,15]. Nevertheless, it is more relevant to consider the experience and policies of each center. It can be advantageous for many centers to consider why certain selection criteria hold greater significance in some centers than in others where they may not have as much impact.

In our previous study, we found that although the total operative time and warm ischemic time were longer in the group with the PLDRH graft >1,000 g than in the groups with the PLDRH graft <1,000 g and the conventional open donor right hepatectomy graft >1,000 g, there were no disparities in the rates of donor or recipient complications [12]. Notably, we observed no significant complications in the group with the PLDRH graft >1,000 g [12]. These positive results are consistent with the results of the present study, in which the number of cases was higher and the follow-up period was longer. As the number of cases of PLDRH with a graft weighing >1,000 g increased, the total operative time decreased slightly and the warm ischemic time decreased significantly. These findings suggest that one of the major drawbacks of PLDRH with a graft weighing >1,000 g was minimized after an increase in the number of cases, as compared to PLDRH with a graft weighing <1,000 g and conventional open donor right hepatectomy with a graft weighing >1,000 g. Moreover, no major complications were observed in any of the donors, further supporting the safety of PLDRH with a graft weighing >1,000 g.

Key factors that have contributed to the feasibility and safety of PLDRH with a graft weighing >1,000 g are the use of a flexible scope and utilization of the hanging maneuver, as needed. Compared with a rigid scope, a flexible scope can provide various surgical views, such as the bird’s eye, low-angle, and lateral views, which are crucial in a limited laparoscopic port site [16]. Given that the liver is a large organ, these surgical views are particularly necessary when handling large liver grafts. The bird’s eye and low-angle views, in particular, are helpful in locating a Nelaton tube between the anterior aspect of the inferior vena cava and the liver and between the middle and right hepatic veins [16]. In cases where mobilization of the right part of the liver segment I becomes challenging owing to the heavy and large liver, the Goldfinger dissector can be applied at almost the final stage of parenchymal dissection between the liver and inferior vena cava. If the surgical field of view is narrow and insufficiently secured, even with a flexible scope, excessive mobilization may cause problems. This can be prevented by using the Goldfinger method.

This study had several limitations. First, it was a single-center retrospective study and the results cannot be generalized. Second, although this study included more patients with a longer follow-up period than those in our previous study, the sample size was still relatively small. However, the strength of this study lies in the fact that a study larger than the present one on PLDRH with a graft size of >1,000 g has not been conducted. While this study alone may not provide a definitive conclusion on the safety and efficacy of PLDRH for grafts >1,000 g, we believe that the results presented here can serve as a valuable reference for other centers seeking to establish their own selection criteria for the procedure.

In conclusion, our experience suggests that skilled surgeons can safely perform PLDRH for grafts weighing >1,000 g with no significant increase in the risk of major complications in both donors and recipients. Therefore, grafts weighing >1,000 g should not be considered contraindications for PLDRH.

There was no funding related to this study.

All authors have no conflicts of interest to declare.

Conceptualization: SKH, KWL. Data curation: SKH. Investigation: SKH, JK, HHC, JL, Jiyoun K, SH, JML. Methodology: SKH. Supervision: KWL. Visualization: SKH. Writing - original draft: SKH. Writing - review & editing: All.