SYSTEMATIC REVIEW AND META-ANALYSIS

Transpl. Int., 09 March 2026

Volume 39 - 2026 | https://doi.org/10.3389/ti.2026.15844

Impact of Vascular Anastomosis Time on Kidney Transplant Outcomes – A Systematic Review

  • KS

    Khaled Sayah 1,2

  • HB

    Henry Burt 1,2† *

  • YZ

    Yizi Zheng 1,2

  • TL

    Taina Lee 2

  • LY

    Lawrence Yuen 2

  • CN

    Christopher Nahm 1,2

  • JY

    Jinna Yao 2

  • WL

    Wai Lim 1,2

  • GW

    Germaine Wong 1,2

  • LL

    Leonard Lee 1,2

  • AH

    Ahmer Hameed 1,2

  • HP

    Henry Pleass 1,2

  • 1. School of Medicine, Faculty of Medicine and Health, The University of Sydney, Sydney, USYD, Australia

  • 2. Westmead Hospital, Westmead, WMH, Australia

Abstract

Anastomotic time (AT), also termed second warm ischaemic time (SWIT), is a potentially important intraoperative factor in kidney transplantation, yet its impact on outcomes has not been systematically synthesised. We conducted a systematic review to examine the association between AT and delayed graft function (DGF), graft survival, and patient survival. Cochrane, Embase, and Medline were searched to 21 July 2025. Nine retrospective cohort studies comprising 155,523 transplants were included. Across all donor types, longer AT was consistently associated with higher rates of DGF within individual studies. Several studies also reported poorer 1- and 5-year graft survival with prolonged AT, while findings for patient survival were equivocal. However, substantial heterogeneity across studies, including donor type, AT definitions, outcome reporting, and incomplete adjustment for key confounders, precluded formal meta-analysis. None of the included studies consistently adjusted for major determinants of graft outcomes. These findings suggest a potential link between prolonged AT and adverse graft outcomes, but high-quality prospective studies with standardised reporting and confounder adjustment are required before AT can be considered an independent determinant of transplant outcomes.

Systematic Review Registration:

https://www.crd.york.ac.uk/prospero/, identifier PROSPERO CRD42024549222.

Graphical Abstract

Introduction

Kidney transplantation is the gold standard treatment for end-stage kidney disease (ESKD), offering substantial improvements in both survival and quality of life compared with dialysis [1, 2]. However, the burden of ESKD continues to grow. In the United States alone, more than 808,000 people are living with ESKD [3]. The transplant waitlist continues to expand, with 90,323 patients listed in 2024, underscoring the critical importance of optimising graft outcomes and extending the longevity of transplanted kidneys [46].

Outcomes after transplantation are influenced by multiple donor and recipient factors, including age, donor pathway, HLA matching, sensitisation, and organ quality [7, 8]. Among perioperative factors, cold ischaemic time (CIT) is well established as a determinant of graft function and survival [912].

Vascular anastomosis time (AT), also referred to as the second warm ischaemic time (SWIT), has similarly been assumed to exert an influence, but has been comparatively under-investigated, and represents the interval from removal of the kidney from ice, until reperfusion in the recipient. It has been acknowledged as a modifiable risk factor, with prolongation of this interval contributing to ischemia-reperfusion injury that drives inflammatory cascades, interstitial fibrosis and tubular atrophy (IFTA), and ultimately reduces graft viability [8, 1318]. The clinical manifestation of this injury is delayed graft function (DGF), often requiring dialysis within the first seven days after transplantation [1315]. Beyond early graft dysfunction, longer SWIT are also associated with longer hospital stays, increased use of renal replacement therapy, and greater reliance on diagnostic resources such as imaging and biopsy, all of which compound the burden on patients and health systems [14].

The first study to explicitly link SWIT to kidney transplant outcomes was published as recently as 2015 [8]. Since then, only a limited number of retrospective cohorts have examined this association, and no systematic review has yet synthesised the available evidence despite the critical role SWIT has on outcomes. As SWIT is a modifiable surgical factor, clarifying its effect is of direct clinical relevance. To address this, we conducted a systematic review to evaluate its association with delayed graft function, one and five-year graft survival, and patient survival in adult kidney transplant recipients.

Materials and Methods

The systematic review was conducted in adherence with the Preferred Items for Systematic Reviews (PRISMA) checklist and was registered with PROSPERO (CRD42024549222) in 2024 [16, 17].

Eligibility Criteria

Articles included in the systematic review were required to have been published between January 2000 – July 2025. AT (SWIT) was required to be reported with a clear description of the term, as well as type of donor graft (DCD, DBD, living donor) used in the study. Studies were required to have a sample size greater than 100, with adult recipients between 18 years or above. Transplant characteristics assessed included DGF, 1- and 5-year graft survival and patient survival. Review articles, articles with majority paediatric or elderly transplants, en bloc kidney transplants, multi-organ transplants, or animal studies were excluded from the systematic review.

Literature Search and Study Selection

Supplementary Table 1 outlines the literature search strategy, developed using a combination of key words and MeSH terms. The following three databases were searched simultaneously via OVID: Cochrane databases for systematic reviews, Embase, and Medline. The final search result was performed on 21st July 2025. Results from the database search was uploaded to COVIDENCE for article screening, as outlined in Supplementary Table 1. Each included study was screened by at least two independent reviewers (KS, HB, YZ, LL), with any conflicts mediated by a third reviewer (HP).

Data Collection

Information from each study was extracted and collated in a standardized table. The following information was documented from each article: Author(s) and study year; type of study; donor type; number of patients in the study; anastomosis time; delayed graft function; 1-year and 5-year graft survival; 1-year and 5-year patient survival. Baseline study characteristics included were Recipient BMI, Recipient Age, Donor BMI, Donor Age, Cause of death (if applicable), Donor serum creatinine, Serum urea, eGFR, and Cold Ischemic Time. This information is outlined on Tables 1, 2, 3. Data extraction was collected individually, then cross-checked by two independent reviewers before being documented on a joint spreadsheet. The terms SWIT and AT are used interchangeably throughout this manuscript.

TABLE 1

Author and YearStudy typePopulation and donor typesRecipient BMI (mean, SD) kg/m2Recipient Age (mean, SD) yearsDonor BMI (Mean, SD) kg/m2Donor age (mean, SD) yearsCause of deathDonor Serum creatinine (mean, SD) μmoL/LSerum Urea (μmoL/L)eGFR (mL/min/1.73 m2)Cold ischemic time (mean, SD) hours
Heylen [19]Retrospective cohort study13,964 (DBD (12, 806), DCD (1,158))25 ± 0.7654.99 ± 2.625 ± 253 ± 2.6NR75.14 ± 2.3NRNR13.7 ± 0.9
Weissenbacher [20]Retrospective cohort study1,245 DBD23.67 ± 3.7451.0224.81 ± 3.52 (mean)45 ± 3DBD: Cerebrovascular accident (587), trauma (358), other (308)83.982,939NR14.53 ± 5.69
Marzouk [14]Retrospective cohort study298 (DBD (n = 282), DCD (n = 16))78 ± 1751 ± 1327 ± 6 (mean)47 ± 17NR67 ± 31NRNR12 ± 1.3
Kukla [21]Retrospective cohort study554 (DBD, DCD (breakdown not available))24.4 ± 0.0947.6 ± 4.225.5 ± 0.0942.8 ± 0.37CVD: 24.8 (23.5–26.2), trauma 24.6 (23.4–25.7), other causes 27.8 (24.8–30.8)NRNRNR18.9 ± 0.1
Tennankore [22]Retrospective cohort study131, 677 (living donor (50, 587), DBD (81,120), DCD (9199)NR50 ± 14NR39 ± 16DBD: (Anoxia: 16, 447), (CVA: 29,375), (Head trauma: 32, 754), (other: 2,514). DCD: 9,199NRNRNR11 ± 2
Mahajan [23]Retrospective cohort study247 (DBD, DCD (breakdown not available))NR53 ± 3.5NR51.8 ± 4.4NRDGF: 78 ± 12; (−) DGF: 69.3 ± 6.1NR1-month eGFR 36.8 ± 3.6; 1-year eGFR 40 ± 3DGF: 840 ± 63 min; No DGF: 824 ± 59 min
Heylen [8]Retrospective cohort study669 (DBD)25 ± 555 ± 13NR48 ± 15DBD63 ± 23NR3-month eGFR 47 ± 17 (n = 646); 1-year eGFR 52 ± 18 (n = 598); 2-year eGFR 52 ± 18 (n = 512); 3-year eGFR 51 ± 20 (n = 373)15 ± 4
Cron [24]Retrospective cohort study6, 397 (DCD)28 ± 1.0455.2 ± 2.426.8 ± 1.138.9 ± 3.2Anoxia (n = 2,724. 42.58), CVA (n = 1,046. 16.35), other/unknown (n = 313. 4.89), trauma (n = 2,314. 36.17)70.4 ± 5.5NRNR17.6 ± 1.2; adjusted odds ratio (1.02) per 1 h
Hellegering [25]Retrospective cohort study472 (living donor)2444.825.550.1N/ANR2 weeks: 157, 1 month:137, 1 year:128NRNR

Baseline study characteristics.

TABLE 2

StudyShort anastomosis time (30–35 min)Long anastomosis time (>35 min)
AT (minutes)Number of participants5-year survival [95% CI]DGFATNumber of participants5-year survival [95% CI]DGF
Heylen [19]<356,08382%NRQ2 = 35–44 min Q3 = 45–54 min Q4 = ≥55 minQ2 = 4,008
Q3 = 2050
Q4 = 1823
Q2 = 81% Q3 = 78% Q4 = 75%NR
Weissenbacher [20]<30NR80.60%NR>30 minNRNRNR
Heylen [8]34 IQR (30–40)659NR17%NRNRNRNR
Cron [24]≤30173188.20%36.70%Q2 = 31–38 min Q3 = 39–47 min Q4 ≥ 48 minQ2 = 1,506
Q3 = 1,584
Q4 = 1,576
Q4 = 84.8%Q2 = 35.2%
Q3 = 40.6%
Q4 = 44.0%
Marzouk [14]30 IQR (24–45)311NR18%NRNRNRNR
Kukla [21]25.2 IQR (24.3–26.1)555NR29.2%NRNRNRNR
Mahajan [23]NRNRNRNR43 IQR (35–48)n = 247NR43.3%
Tennankore [22]Q1 = <10
Q2 = 10 - <20 Q3 = 20 - <30
Q1 = 13,456
Q2 = 3,715
Q3 = 21,627
Q1 = 78% [77%–79%]
Q2 = 80% [78%–81%]
Q3 = 78% [78%–79%]
NRQ4 = 30 - <40
Q5 = 40 - <50
Q6 = 50 - <60
Q7 ≥ 60
Q3 = 38,403
Q4 = 27,058
Q5 = 10,818
Q6 = 16,600
Q4 = 75% [75%–76%]
Q5 = 74% [73%–75%] Q6 = 73% [72%–74%]
NR
Hellegering [25]29.8 minn = 477NR4.40%NRNRNRNR

Comparing shorter to longer anastomosis times.

TABLE 3

Donor TypeStudyNumber of participantsDGF (%)1-year graft survival (%)5-year graft survival (%)1-year patient survival (%)5-year patient survival (%)
Short ATLong ATShort ATLong ATShort ATLong ATShort ATLong ATShort ATLong AT
DBDHeylen [8]669179585
Weissenbacher [20]1,24533.1939080.676.689.685.7
Kukla [21]55429.2
DCDCron [24]6,3973642.396.794.789.185.996.796.287.887.6
DCD + DBDHeylen [19]13,96488868279.5
Marzouk [14]29818.8
Mahajan [23]27943.3
Living + deceasedTennankore [22]131,6779491.878.574.7
Living onlyHellegering [25]4774.4%

Comparing short (<30 min) to longer AT (>30–35 min).

Formulation of Results

Given substantial heterogenicity across included studies, including differences in donor type, AT definitions, comparator thresholds, missing covariate reporting, surgical complexity and inconsistent outcome stratification, formal meta-analysis was not undertaken following statistical consultation. Quantitative pooling of outcomes across studies was not performed, as doing so would risk biasing data or producing misleading estimates from clinically and methodologically incomparable data. Simple pooling approaches such as weighted arithmetic means were considered inappropriate for this dataset. Instead, a structured narrative synthesis was conducted. Outcomes were summarised within each study, and patterns of associated trends between AT and transplant outcomes were described across donor types. Studies were grouped by donor type (DBD, DCD, living donor and mixed cohorts) and by AT threshold where applicable. Direction and consistency of reported effects were assessed descriptively for delayed graft function, graft survival and patient survival.

Risk of Bias Assessment

Retrospective cohort studies were assessed for risk of bias using the Newcastle-Ottawa scale (Table 4) [18]. This tool evaluates bias across multiple domains, including the representation of exposed cohort, the selection of a non-exposed cohort, ascertainment of exposure, demonstration that the outcome was not present at the initial investigation of the study, comparability of included cohorts, and assessment of the outcome with adequate follow-up time [18].

TABLE 4

Newcastle-Ottowa clinical assessment
ReferencesRepresentation of exposed cohortSelectionComparabilityOutcome/ExposureAdequecy of follow-up cohortsTotal score
Selection of non-exposed cohortAscertainment of exposureDemonstration that the outcome was not present at the start of the studyComparability of cohort on the basis of the design or analysis controlled for confoundersAssessment of the outcomeFollow-up time was appropriate for outcomes to occur
Heylen [19]111121108 good quality
Weissenbacher [20]111121119 good quality
Marzouk [14]111120006 fair quality
Kukla [21]111121119 good quality
Tennankore [22]111121017 good quality
Mahajan [23]111120107 good quality
Heylen [8]111121108 good quality
Hellegering [25]111121108 good quality
Cron [24]111121108 good quality

Newcastle-Ottawa assessment.

Certainty of Evidence

For each comparison, certainty of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework [26]. Outcome chosen for certainty assessments included Delayed Graft function, 1 and 5-year Graft Survival, and 1- and 5- year Patient Survival [26]. All included studies were retrospective observational cohorts and were therefore initially rated as low-certainty evidence. Longer anastomosis time was consistently associated with higher rates of delayed graft function and poorer graft survival within individual studies, but findings for patient survival were inconsistent. Certainty was downgraded due to residual confounding, heterogenicity in anastomosis time thresholds, and incomplete adjustment for key covariates, including cold ischaemic time, graft type and surgical complexity. Overall, the certainty of evidence across outcomes was rated as low to moderate, reflecting the observational design, heterogenicity and high likelihood of residual confounding. No pooled quantitative effect estimates were generated.

Results

A total of 9 retrospective cohort studies were included in the systematic review, with a total combined data spread of 155, 523 patients across two continents of North America and Europe. The PRISMA flow chart is outlined in Figure 1.

FIGURE 1

Population Characteristics

Across the 9 retrospective cohort studies, population characteristics were sectioned into recipient and donor patient characteristics. Of the recipient population, reported BMI ranged from 23.7 kg/m2 to 28.0 kg/m2, and the median age was 51.2 IQR (48.8–55.0). With respect to the donor population, the median age was 47 IQR (40.9–70.0). Donor types were recorded as living donors (n = 51, 059), donation after circulatory death (n = 16, 770), and donation after brain death (n = 96, 122). For the deceased donor population, the cause of death was included if available in the retrospective cohort study.

Study Characteristics

Three studies used a mixed kidney donor population of deceased donors consisting of both donation after circulatory death (DCD) and donation after brain death (DBD) [14, 19, 23]. Three studies used only DBD donors [8, 20, 21], one study limited the donor type to DCD [24], one utilized living donors [25], and the last study used a mix of both living and deceased donors [22].

Evidence and Reporting Bias

A summary of the Newcastle-Ottawa risk of bias assessment is provided in Table 3. All studies included provided a clear description of the donor type used in their respective studies and specified the AT intervention and comparator used in their analysis. Some studies failed to provide an adequate assessment of outcome and did not provide an adequate follow-up time for long term graft outcomes to be assessed. Eight studies included maintained a good quality score ranging from 7 to 9. One of the studies included was determined as Fair quality with a rating of 6 due to the above rationale.

Overall quality of evidence was summarized in accordance with the GRADE evidence profile on Table 5 [26]. The quality of evidence was moderate for all measurable outcomes investigated. Study evidence was reduced due to all the studies included being retrospective cohort studies, and the different donor types used to assess each outcome.

TABLE 5

Outcome typeNo. of studiesRisk of bias/Quality of evidenceConsistencyDirectnessPrecisionPublication biasOverall effect size estimate (95% CI)Quality of evidence
Delayed graft function (DGF)7 (7 cohort)Low risk of bias; observational evidenceMinimal inconsistencyDirect (0)Narrow CI; large sample size; high precisionNo important publication bias1.10 per 10 min (1.06–1.14)Moderate
1-year Patient Survival3 (3 cohort)Low risk of bias; observational evidence, howeverMinimal inconsistencyDirect (0)Narrow CI; large sample size; high precisionNo evident publication bias1.021 per minute (1.006–1.037)Moderate
5-year Patient Survival4 (4 cohort)Low risk of bias; observational studySome inconsistencyDirect (0)Narrow CI; large sample sizeNo evident publication bias3.5 (1.6–7.3)Moderate
5-year Graft Survival4 (4 cohort)Low risk of bias; observational studyMinimal inconsistencyDirect (0)Narrow CI and large sample sizeNo evident publication bias1.23 (1.15–1.33)Moderate

Grading of recommendations, assessment, development and evaluations (GRADE).

Anastomosis Time Across Studies

Across the nine included studies, definitions of “short” and “long” AT varied, with thresholds ranging from <30 min to <35 min for shorter AT, and >30 min to >55 min for prolonged AT [8, 14, 21, 2325]. Several studies reported AT quartiles rather than binary cut-offs [19, 22, 24]. In large registry-based cohorts, only a minority of recipients fell within the shortest AT category [22, 24]. Small, single centre studies reported median AT values ranging from 25 to 45 min, with wide interquartile ranges [8, 21, 23]. These findings suggest that achieving and AT <30 min is feasible in selected cases, particularly living donor transplantation, but may be uncommon in complex, deceased donor scenarios.

Anastomosis Time and Delayed Graft Function

Seven studies analysed the relationship between vascular AT and the incidence of DGF in kidney transplantation [8, 14, 21, 2325]. Across all donor types, longer AT were associated with higher rates of DGF (Table 2). In one study examining DBD recipients who developed DGF had significantly longer median AT compared to those without [8]. In another study examining DCD recipients, a similar effect was noted, with higher rates of DGF across increasing AT quartiles [24]. These directional associations were observed in mixed donor cohorts [19, 23], and in living donor cohorts [25], although effect sizes varied across studies. Due to heterogenicity in AT thresholds, donor populations, and outcome definitions, no pooled estimates of DGF risk were calculated.

Anastomosis Time and Graft Survival

Five studies analysed the effect of AT on 1 and 5-year graft survival, with all studies reporting statistically significant findings, consistently demonstrating that graft survival at both time points was superior in cohorts with shorter AT [8, 19, 20, 22, 24] (Table 2). One study demonstrated a graded decline in 5-year graft survival across increasing AT quartiles [19]. One study reported inferior graft survival beyond an AT threshold of 30 min [20]. One study observed lower graft survival with prolonged AT in DCD transplantation [24]. Given differences in study design, donor populations, AT categorisations and outcome reporting, pooled graft survival estimates were not generated.

Anastomosis Time and Patient Survival

One study with the predetermined criteria reported data on 1-year patient survival [8, 20, 24], and four reported a 5-year patient survival [8, 20, 22, 24]. For patient survival, no study found an effect of AT at 1 year, and results at 5 years were mixed. Some cohorts reported poorer survival with prolonged AT, while others showed no independent association. Taken together, the evidence suggests AT primarily influences graft-level outcomes, while its impact on patient-level survival remains uncertain [8, 20, 22, 24].

Discussion

This review is, to our knowledge, the first systematic synthesis of vascular AT and kidney transplant outcomes across donor types. In the studies involved, prolonged AT was associated with higher rates of DGF across all donor types, and as expected the lowest incidence was seen in living donor grafts, intermediate rates in donation after brain death, and the highest rates in donation after circulatory death. In the studies involved, shorter AT, particularly under 30 min, were associated with superior graft survival, whereas both one-year and five-year graft survival declined once this interval was exceeded. Impacts on patient survival were less clear.

These findings support the interpretation that AT, DGF, and graft survival are best understood as a connected pathway rather than independent outcomes. Prolonged AT consistently increased the risk of DGF, and poorer long-term graft survival was observed in the same cohorts. Because DGF itself is a well-recognised predictor of graft loss, it is plausible that the adverse impact of prolonged AT on survival is mediated in part through its effect on early graft function. This biological plausibility is consistent with the known mechanisms of ischemia-reperfusion injury and lends coherence to the observed clinical outcomes [15].

The modifiability of vascular AT highlights its potential as a risk factor that could be improved through revised surgical techniques and guidelines. Current clinical guidelines from the Transplantation Society of Australia and New Zealand (TSANZ) do not specify an optimal vascular AT but emphasize the importance of minimising cold ischemic time [27]. Additionally, the guidelines highlight strong evidence that a short ischemic time may improve transplant outcomes, recommending that kidneys be transplanted as quickly as possible to mitigate prolonged cold ischemia [27]. However, various factors influencing vascular AT must be considered when promoting speed and precision. These include anatomical complexities (e.g., multiple renal arteries/veins, right-sided kidney grafts), recipient and donor characteristics (BMI, depth, and Age) [8, 2830]. This emphasizes the need to recognize AT as a modifiable risk factor and incorporate its optimization into surgical planning within the transplant community and has impacts on transplant surgical training, as well as the introduction of robotic kidney transplantation more broadly.

Importantly, AT is not solely a function of surgical technique or efficiency, but also reflects surgical complexity. Prolonged AT commonly occurs in technically challenging scenarios, including ipsilateral re-transplantation, difficult iliac vessel exposure, high recipient BMI, deep iliac fossae, and the presence of calcified vessels, to name but a few [31]. In such cases, prolonged AT may be unavoidable and appropriate to ensure technical precision and haemostatic security. Accordingly, AT may act a s a surrogate marker of procedural complexity rather than an independent causal factor of poor transplant outcomes.

Cold ischaemic time is a well-established independent predictor of graft outcomes and is biologically distinct from AT [9, 11]. While AT and CIT are temporally separate, they are likely biologically synergistic. Prolonged AT may be particularly injurious in kidneys already exposed to extended cold storage, as warm re-ischemia following prolonged hypothermia may amplify ischemia reperfusion injury. This potential interaction, however, is beyond the scope of this review but remains a hypothetical, though clinically plausible mechanism, warranting prospective evaluation.

The feasibility of achieving AT below 30 min also warrants consideration. Registry based data suggests that a substantial proportion of deceased donor transplants exceed this threshold, particularly in DCD cohorts [8, 19, 20]. Short AT is most achievable in living donor cohorts, and straightforward deceased donor cases. Thresholds used across studies in this review, were arbitrary and heterogenous, and no evidence-based cut-off for “safe” AT currently exists.

These findings support viewing AT as a modifiable intra-operative factor with meaningful consequences for both early graft function and long-term graft durability. Minimisation can be encouraged through thorough preparation at the pre-operative briefing, with clear allocation of roles, readiness of instruments, and vascular exposure achieved before removal of the kidney from ice. Further, recording AT as a routine peri-operative quality measure would allow teams to monitor performance and provide constructive feedback. Workflow can also be streamlined, for example, by using a two-surgeon approach where possible and by preparing sutures or clamps in advance so that periods of non-productive time are reduced. An alternative approach would be to incorporate active methods of insulating and/or cooling the graft during anastomoses, to ameliorate the negative impacts of rapid graft rewarming and warm ischemia during this interval.

Several limitations must be recognised in this review, however. Important covariates such as cold ischaemic time, first warm ischemia, multiplicity of vessels, side of graft, recipient body mass index, machine perfusion, and centre or era effects were not consistently adjusted for. We also could not conduct formal meta-analyses and sensitivity analyses given significant differences in donor populations between different studies, variable use and reporting of technologies such as machine perfusion, and variable/inconsistent reporting of all relevant study outcomes stratified by AT thresholds and donor types.

Despite these limitations, the review has notable strengths. It is, to our knowledge, the first systematic review to focus specifically on vascular AT in kidney transplantation. Large and contemporary cohorts were included, stratified by donor type, and the overall risk of bias was low, with eight of the nine studies assessed as good quality. Taken together, this synthesis provides a structured overview of the available evidence and highlights areas where prospective research with standardised definitions and reporting would add the most value.

Conclusion

This systematic review identified studies that found an inverse relationship between AT and graft survival. A shorter AT was associated with a superior immediate graft function, and 1-year and 5-year graft survival, across all types of donor recipients. Currently, there are no guidelines that define the significance of maintaining a short AT for optimal graft function and survival. This systematic review aims to inform the transplant community on the importance of maintaining a short AT, where possible, to provide the most optimal outcome post-operatively.

Statements

Data availability statement

The original contributions presented in the study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding author.

Ethics statement

Ethical approval was not required for the study involving humans in accordance with the local legislation and institutional requirements. Written informed consent to participate in this study was not required from the participants or the participants’ legal guardians/next of kin in accordance with the national legislation and the institutional requirements.

Author contributions

KS, HB, and YZ were responsible for article screening and inclusion, with any conflicts resolved by a HP. AH provided statistical support. KS, HB, YZ, and LL were responsible for writing of the manuscript, with revision by TL, LY, CN, JY, WL, GW, AH, and HP. All authors contributed to the article and approved the submitted version.

Funding

The author(s) declared that financial support was not received for this work and/or its publication.

Acknowledgments

Statistical advice was sought from Dr. Ahmer Hameed, and we wish to acknowledge their support.

Conflict of interest

HP and AH would like to declare a conflict of interest in that they are shareholders in iiShield Ltd, a start-up company aiming to design an insulating jacket to be utilised during kidney transplantation.

The remaining author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Generative AI statement

The author(s) declared that generative AI was not used in the creation of this manuscript.

Any alternative text (alt text) provided alongside figures in this article has been generated by Frontiers with the support of artificial intelligence and reasonable efforts have been made to ensure accuracy, including review by the authors wherever possible. If you identify any issues, please contact us.

Supplementary material

The Supplementary Material for this article can be found online at: https://www.frontierspartnerships.org/articles/10.3389/ti.2026.15844/full#supplementary-material

Abbreviations

AT or SWIT, Anastomosis time or second warm ischemic time; CIT, Cold ischemic time; CI, confidence interval; DBD, donation after brain death; DCD, donation after cardiac death; DGF, Delayed graft function; DWIT or FWIT, Donor warm ischemic time or first warm ischemic time; EGF, Early graft function; ESKD, End stage kidney disease; HR, Hazard ratio; IFTA, Interstitial fibrosis and tubular atrophy; IGF, Immediate graft function; NR, Not reported; OR, odds ratio; RR, Relative risk; SD, Standard deviation; SGF, Slow graft function; SWIM, systematic review without meta-analysis; TSANZ, Transplantation Society of Australia and New Zealand; Tx, Transplant outcomes.

References

  • 1.

    VooraSAdeyDB. Management of Kidney Transplant Recipients by General Nephrologists: Core Curriculum 2019. Am J Kidney Dis (2019) 73:86679. 10.1053/j.ajkd.2019.01.031

  • 2.

    Health AIo and Welfare. Dialysis and Kidney Transplantation in Australia: 1991-2010. Canberra: AIHW (2012).

  • 3.

    Data. UOPTN. Health Resources and Services Administration. (2024).

  • 4.

    United States Renal Data System. 2023 USRDS Annual Data Report: Epidemiology of Kidney Disease in the United States. Bethesda, MD: National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases (2023).

  • 5.

    GuptaRWooKYiJA. Epidemiology of End-Stage Kidney Disease. Semin Vasc Surg (2021) 34:718. 10.1053/j.semvascsurg.2021.02.010

  • 6.

    AbecassisMBartlettSTCollinsAJDavisCLDelmonicoFLFriedewaldJJet alKidney Transplantation as Primary Therapy for End-Stage Renal Disease: A National Kidney Foundation/Kidney Disease Outcomes Quality Initiative (NKF/KDOQITM) Conference. Clin J Am Soc Nephrol (2008) 3:47180. 10.2215/cjn.05021107

  • 7.

    SchaapherderAFKaisarMMumfordLRobbMJohnsonRde KokMJCet alDonor Characteristics and Their Impact on Kidney Transplantation Outcomes: Results from Two Nationwide Instrumental Variable Analyses Based on Outcomes of Donor Kidney Pairs Accepted for Transplantation. EClinicalMedicine (2022) 50:101516. 10.1016/j.eclinm.2022.101516

  • 8.

    HeylenLNaesensMJochmansIMonbaliuDLerutEClaesKet alThe Effect of Anastomosis Time on Outcome in Recipients of Kidneys Donated After Brain Death: A Cohort Study. Am J Transpl (2015) 15:29007. 10.1111/ajt.13397

  • 9.

    Peters-SengersHHoutzagerJHEIduMMHeemskerkMBAvan HeurnELWHoman van der HeideJJet alImpact of Cold Ischemia Time on Outcomes of Deceased Donor Kidney Transplantation: An Analysis of a National Registry. Transpl Direct (2019) 5:e448. 10.1097/txd.0000000000000888

  • 10.

    SummersDMJohnsonRJAllenJFuggleSVCollettDWatsonCJet alAnalysis of Factors that Affect Outcome After Transplantation of Kidneys Donated After Cardiac Death in the UK: A Cohort Study. Lancet (2010) 376:130311. 10.1016/s0140-6736(10)60827-6

  • 11.

    van de LaarSCLafrancaJAMinneeRCPapaloisVDorFJMF. The Impact of Cold Ischaemia Time on Outcomes of Living Donor Kidney Transplantation: A Systematic Review and Meta-Analysis. J Clin Med (2022) 11:20220315. 10.3390/jcm11061620

  • 12.

    FoleyDPSawinskiD. Personalizing Donor Kidney Selection: Choosing the Right Donor for the Right Recipient. Clin J Am Soc Nephrol (2020) 15:41820. 10.2215/CJN.09180819

  • 13.

    OjoAOWolfeRAHeldPJPortFKSchmouderRL. Delayed Graft Function: Risk Factors and Implications for Renal Allograft Survival. Transplantation (1997) 63:96874. 10.1097/00007890-199704150-00011

  • 14.

    MarzoukKLawenJAlwaynIKiberdBA. The Impact of Vascular Anastomosis Time on Early Kidney Transplant Outcomes. Transpl Res (2013) 2(8):20130515. 10.1186/2047-1440-2-8

  • 15.

    ZhaoHAlamASooAPGeorgeAJTMaD. Ischemia-Reperfusion Injury Reduces Long Term Renal Graft Survival: Mechanism and Beyond. EBioMedicine (2018) 28:3142. 10.1016/j.ebiom.2018.01.025

  • 16.

    PageMJMcKenzieJEBossuytPMBoutronIHoffmannTCMulrowCDet alThe PRISMA 2020 Statement: An Updated Guideline for Reporting Systematic Reviews. BMJ (2021) 372:n71. 10.1136/bmj.n71

  • 17.

    SayahK* BHHameedAPleassH. Impact of Vascular Anastomosis Times on Kidney Transplant Outcomes - a Systematic Review. In: PROSPERO 2024 CRD42024549222 (2024).

  • 18.

    Ga WellsBSO'ConnellDPetersonJWelchVLososMTugwellP. The Newcastle-Ottawa Scale (NOS) for Assessing the Quality of Nonrandomised Studies in Meta-Analyses. Ferrara, Italy: MDPI (2024).

  • 19.

    HeylenLPirenneJSamuelUTiekenINaesensMSprangersBet alThe Impact of Anastomosis Time During Kidney Transplantation on Graft Loss: A Eurotransplant Cohort Study. Am J Transpl (2017) 17:72432. 10.1111/ajt.14031

  • 20.

    WeissenbacherAOberhuberRCardiniBWeissSUlmerHBösmüllerCet alThe Faster the Better: Anastomosis Time Influences Patient Survival After Deceased Donor Kidney Transplantation. Transpl Int (2015) 28:53543. 10.1111/tri.12516

  • 21.

    KuklaUCholewaHChronowskaJGocTLieberEKolonkoAet alEffect of the Second Warm Ischemia Time and Its Components on Early and Long-Term Kidney Graft Function. Transpl Proc (2016) 48:13659. 10.1016/j.transproceed.2015.11.042

  • 22.

    TennankoreKKKimSJAlwaynIPKiberdBA. Prolonged Warm Ischemia Time Is Associated with Graft Failure and Mortality After Kidney Transplantation. Kidney Int (2016) 89:64858. 10.1016/j.kint.2015.09.002

  • 23.

    MahajanNHeerMKTrevillianPR. Renal Transplant Anastomotic time-Every Minute Counts!. Front Med (Lausanne) (2022) 9:1024137. 10.3389/fmed.2022.1024137

  • 24.

    CronDCMurakamiNXiangLMarkmannJFYehHAdlerJT. Anastomosis Time and Outcomes After Donation After Circulatory Death Kidney Transplantation. J Am Coll Surg (2022) 234:9991008. 10.1097/XCS.0000000000000174

  • 25.

    HellegeringJVisserJKlokeHJD'AnconaFCHHoitsmaAJvan der VlietJAet alPoor Early Graft Function Impairs Long-Term Outcome in Living Donor Kidney Transplantation. World J Urol (2013) 31:9016. 10.1007/s00345-012-0835-z

  • 26.

    GuyattGOxmanADAklEAKunzRVistGBrozekJet alGRADE Guidelines: 1. Introduction—GRADE Evidence Profiles and Summary of Findings Tables. J Clin Epidemiol (2011) 64:38394. 10.1016/j.jclinepi.2010.04.026

  • 27.

    Tsanz Clinical Guidelines. The Transplantation Society of Australian and New Zealand (2024).

  • 28.

    Vacher-CoponatHMcDonaldSClaytonPLoundouAAllenRDMChadbanSJ. Inferior Early Posttransplant Outcomes for Recipients of Right Versus Left Deceased Donor Kidneys: An ANZDATA Registry Analysis. Am J Transpl (2013) 13:399405. 10.1111/j.1600-6143.2012.04312.x

  • 29.

    DobrijevicELKAuEHKRogersNMClaytonPAWongGAllenRDM. Association Between Side of Living Kidney Donation and Post-Transplant Outcomes. Transpl Int (2022) 35:10117. 10.3389/ti.2022.10117

  • 30.

    KulkarniSWeiGJiangWLopezLAParikhCRHallIE. Outcomes from Right Versus Left Deceased-Donor Kidney Transplants: A US National Cohort Study. Am J Kidney Dis (2020) 75:72535. 10.1053/j.ajkd.2019.08.018

  • 31.

    LyuJHouYWangZZhuY. The Relationship Between Surgical Difficulty and Postoperative Complications in Kidney Transplantation: Establishment of a Preoperative Prediction Model. Urologia Internationalis (2025) 109(5):45362. 10.1159/000543458

Summary

Keywords

anastomosis, second warm ischaemic time, surgical, surgical anastomosis, transplant

Citation

Sayah K, Burt H, Zheng Y, Lee T, Yuen L, Nahm C, Yao J, Lim W, Wong G, Lee L, Hameed A and Pleass H (2026) Impact of Vascular Anastomosis Time on Kidney Transplant Outcomes – A Systematic Review. Transpl. Int. 39:15844. doi: 10.3389/ti.2026.15844

Received

04 November 2025

Revised

11 February 2026

Accepted

17 February 2026

Published

09 March 2026

Volume

39 - 2026

Updates

Copyright

*Correspondence: Henry Burt,

†These authors share first authorship

Disclaimer

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

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