Since the first reported pure laparoscopic donor hepatectomy (PLDH) in 2002 [1], the growing focus on donor cosmesis and functional outcomes, coupled with advancements in laparoscopic instruments and the accrued experience in pure laparoscopic hepatectomy, has led to a rising trend in the performance of PLDHs. International consensus guidelines for minimally invasive hepatectomy, including PLDH, have undergone continuous updates [2-5]. Pure laparoscopic donor left lateral sectionectomy has achieved the status of a standard procedure for proficient surgical teams [2-5]. However, the utilization of pure laparoscopic donor full left and full right hepatectomy remains limited to select, highly experienced centers, often reserved for specific cases. Further studies are imperative to support their adoption as widely accepted standards of practice.

Our center has conducted multiple studies that demonstrate the feasibility and safety of pure laparoscopic donor right hepatectomy (PLDRH) [6-8]. Our research indicates that PLDRH offers advantages in donor surgery such as reduced blood loss, shorter hospital stays, and comparable complication rates when compared to conventional donor right hepatectomy (CDRH) [6-8]. However, it is important to note that PLDRH may be associated with a higher incidence of biliary complications in the recipient [6-8]. Additionally, achieving graft quality similar to that in CDRH requires more time and additional procedures during bench-surgery [9]. While the sample size for pure laparoscopic donor left hepatectomy (PLDLH) was relatively smaller compared to PLDRH, it yielded comparable results, including a shorter hospital stay and similar postoperative complications for both donors and recipients [10]. Although PLDLH may have a similar effect on graft quality, it’s worth noting that previous studies on PLDLH did not thoroughly assess its impact on graft quality. This study aimed to conduct a comparative analysis of bench-surgery time between PLDLH and conventional donor left hepatectomy (CDLH), building upon previous research focused on PLDLH [10].

The study protocol adhered to the ethical principles outlined in the 1975 Declaration of Helsinki and received approval from the institutional review board of Seoul National University Hospital (Approval Number: 1907-198-1054). We retrospectively reviewed the medical records of donors who underwent PLDLH, including the middle hepatic vein (MHV), from November 2015 to January 2018. In addition, we examined the records of donors who underwent CDLH, also involving the MHV, during the period from August 2014 to September 2015. This specific two-year window was chosen to encompass the most recent period during which donors exclusively underwent conventional donor hepatectomy, minimizing potential time-related biases.

Statistical Analysis

The results are reported using either medians and ranges or numerical values and percentages. To compare categorical variables, we employed either the chi-square test or Fisher’s exact test, as deemed appropriate. For continuous variables between different groups, the Mann-Whitney U test was applied. Significance was established at p<0.05. All statistical analyses were conducted using IBM SPSS software, version 23 (IBM Corp., Armonk, NY, USA).

While CDLH data is limited to the two most recent years, except for bench-surgery time and the counts of orifices for the hepatic vein, portal vein, hepatic artery, and bile duct, we can obtain demographic and operative outcome details for donors and recipients from our previous study. [10]. Bench-surgery time was significantly longer in PLDLH compared to CDLH (24.0 vs. 45.0 min; p=0.028), similar with liver removal time (177.0 vs. 244.5 min; p=0.038) and warm ischemic time (3.0 vs. 10.5 min; p<0.001) (Table 1, Fig. 1). Graft weight and the number of openings of hepatic vein, portal vein, hepatic artery, and bile duct were comparable between the two groups. The proportion of hepatic venoplasty was also comparable between the two groups.

Table 1 .. Demographic characteristics and operative outcomes for CDLH and PLDLH.

Variable	CDLH	PLDLH	p-value
Sex (male:female)	7:1	8:0	0.999
Adult to recipient	1 (12.5)	1 (12.5)	0.999
Relationship			0.999
Son/daughter	5	5
Father/mother	1	1
Brother/sister	1	1
Husband/wife	1	1
Operative time (min)	275.0 (191.0–335.0)	332.5 (215.0–410.0)	0.065
Liver removal time (min)	177.0 (115.0–211.0)	244.5 (156.0–329.0)	0.038
Warm ischemic time (min)	3.0 (1.0–9.0)	10.5 (8.0–33.0)	<0.001
Bench-surgery time (min)	24.0 (5.0–80.0)	45.0 (26.0–81.0)	0.028
Graft weight (g)	425.0 (281.0–580.0)	449.0 (385.0–610.0)	0.382
No. of openings in the procured graft
Hepatic vein			0.413
1	3 (37.5)	5 (62.5)
2	4 (50.0)	1 (12.5)
3	1 (12.5)	2 (25.0)
Portal vein
1	8 (100)	8 (100)	-
Hepatic artery			0.077
1	4 (50.0)	8 (100)
2	4 (50.0)	0
Bile duct			0.200
1	8 (100)	5 (62.5)
2	0	2 (25.0)
3	0	1 (12.5)
Hepatic venoplasty	5 (62.5)	3 (37.5)	0.619

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

CDLH, conventional donor left hepatectomy; PLDLH, pure laparoscopic donor left hepatectomy..

Figure 1. Bench-surgery time comparison between CDLH and PLDLH. PLDLH, pure laparoscopic donor left hepatectomy; CDLH, conventional donor left hepatectomy.

Subgroup analyses were specifically conducted within the PLDLH group to examine potential variations in operative time, liver removal time, warm ischemic time, and bench-surgery time as the number of PLDLH cases increased (Fig. 2). Although there was no noticeable trend indicating a reduction in warm ischemic time (p=0.352) and bench-surgery time (p=0.456) with an increase in case numbers, there was a significant decrease in operative time (Rho=−0.810, p=0.015) and liver removal time (Rho=-0.905, p=0.002) as the number of cases increased. Conversely, when focusing on the CDLH group, subgroup analyses revealed no discernible trend indicating a reduction in operative time (p=0.911), liver removal time (p=0.823), warm ischemic time (p=0.798), or bench-surgery time (p=0.888) with an increase in case numbers.

Figure 2. Correlation between (A) operative time, (B) liver removal time, (C) warm ischemic time, and (D) bench-surgery time in relation to the progressive performance of pure laparoscopic donor left hepatectomy.

As our preference in living donor liver transplantation (LDLT) leans towards utilizing full right liver grafts [11,12], instances of donor full left hepatectomy are relatively rare, making it challenging to conduct a comprehensive comparison of the effects of PLDRH and PLDLH. Nonetheless, there are situations where opting for a full left liver graft is more suitable, factoring in considerations such as anatomical compatibility, remnant liver volume, and the graft-to-recipient weight ratio [10]. Consequently, it becomes essential to evaluate the impact of PLDLH in contrast to CDLH. Considering that the central issue revolves around comparing pure laparoscopic techniques to open techniques, the effects of PLDLH versus CDLH are expected to parallel those observed in the comparison of PLDRH and CDRH. As expected, our prior study on PLDLH revealed an extended warm ischemic time, shorter hospital stays, and comparable postoperative complications in both donors and recipients when comparing PLDLH to CDLH [10].

This study revealed significantly longer liver removal time, warm ischemic time, and bench- surgery time in PLDLH cases compared to CDLH cases. Although the difference in operative time did not reach statistical significance, there was a trend toward longer operative time in the PLDLH group as well. It is crucial to take the learning curve effect into account when interpreting the results [13]. As the number of PLDLH cases increased, both operative time and liver removal time decreased significantly, indicating the impact of the learning curve. In light of this, the trend toward longer operative time in PLDLH compared to CDLH suggests no significant difference in operative time after overcoming the learning curve associated with PLDLH. After overcoming the learning curve, the disparity in liver removal time between PLDLH and CDLH could potentially be minimized or even become comparable. This trend aligns with our previous findings in PLDRH, where total operative time was initially longer in the early period but became shorter in more recent cases, surpassing the efficiency of CDRH [14]. This improvement can be attributed to the advantage of reducing time spent on closing the abdominal wall during the procedure. Nevertheless, this study found that warm ischemic time and bench-surgery time did not decrease with an increase in the number of cases, indicating inherent characteristics of the pure laparoscopic technique. These factors do not seem to be improvable through mere accumulation of experience.

This study centers on bench-surgery, which serves as an indicator of graft quality. Similar to PLDRH, we observed that bench-surgery time was significantly longer in PLDLH compared to CDLH. According to our previous study on PLDRH, the extended bench-surgery time can be attributed to factors such as a relatively short and intricate vascular stump, necessitating additional maneuvers like stump trimming and dissection of the surrounding liver parenchyma [9]. Additionally, there are extra steps involved, such as the removal or replacement of clips or stapler lines for hand suture closure.

When utilizing a full left liver graft that includes the MHV, there is no need for the typical MHV reconstruction, which is typically performed in cases involving full right liver grafts. In some instances, venoplasty procedures, such as direct venoplasty, fence venoplasty, and quilt venoplasty, may be required for hepatic vein reconstruction during bench-surgery [15]. However, many cases do not necessitate any plasty procedures for the hepatic vein, nor do they require additional interventions for the portal vein, hepatic artery, and bile duct. Consequently, bench-surgery in donor left hepatectomy tends to be shorter compared to donor right hepatectomy. In our study, the median bench-surgery time was 45.0 minutes for PLDLH. This finding aligns with our prior research, which encompassed 541 cases of PLDRH and 12 cases of PLDLH, demonstrating that the mean bench-surgery time for PLDRH was 60.0 minutes, while the median bench-surgery time for PLDLH was 45.0 minutes [8].

The duration of bench-surgery in donor left hepatectomy appears to be primarily driven by the necessity for hepatic venoplasty. Notably, there were no significant differences observed in the number of hepatic vein openings within the procured left liver and the proportion of cases requiring hepatic venoplasty when comparing CDLH and PLDLH. However, it’s worth mentioning that in CDLH, approximately half of the cases displayed multiple hepatic artery openings, while none of the PLDLH cases had multiple hepatic artery openings, although this distinction did not attain statistical significance. Despite this, the longer bench-surgery time in PLDLH compared to CDLH could be attributed not to specific venoplasty but to general tasks such as trimming the stumps of the hepatic vein, portal vein, hepatic artery, and bile duct, as well as dissecting the surrounding liver parenchyma. The need for these additional steps during bench-surgery implies a lower graft quality, which, in turn, necessitates extra procedures to ensure the graft meets the necessary standards for successful implantation in the recipient. This approach helps achieve comparable transplant outcomes between CDLH and PLDLH.

This study is subject to several limitations. Firstly, the relatively small sample size may have reduced the statistical power of our analysis. Secondly, the study relies on data from a single center, making it challenging to extrapolate the findings to other centers. Thirdly, despite our deliberate inclusion of CDLH for comparison, which was conducted in the most recent period prior to the establishment of PLDH as the standard procedure in our center, some degree of time-related bias may still exist. Nevertheless, to the best of our knowledge, this is the first study to objectively demonstrate a longer bench-surgery time in PLDLH compared to CDLH. Based on this finding, we can infer that graft quality may be lower in PLDLH compared to CDLH, similar to the comparison between CDRH and PLDRH. It highlights that graft quality is influenced by whether the procedure is purely laparoscopic or not, rather than whether it involves a right or left liver graft.

In conclusion, our experience suggests that PLDLH necessitates extra steps during bench-surgery, leading to a longer duration compared to CDLH. Therefore, a skilled surgical team in both bench-surgery and recipient surgery is essential for PLDLH to attain outcomes on par with CDLH in recipients.

There was no funding related to this study.

All authors have no conflicts of interest to declare.

Conceptualization: SKH. Data curation: SKH, MK, YK, JYK, JL, JK, SYH. Formal analysis: SKH. Investigation: SKH. Methodology: SKH. Resources: SKH. Supervision: SKH. Validation: SKH. Visualization: SKH. Writing – original draft: SKH. Writing – review & editing: All.