Intraoperative unfractionated heparin (UFH) for kidney transplantation: A systematic review and meta-analysis.

INTRODUCTION

Balancing bleeding risk with graft thrombosis is a challenge in transplantation surgery. This systematic review assessed the efficacy and safety of intraoperative administration of intravenous (IV) unfractionated heparin (UFH) bolus during adult kidney transplantation.

METHODOLOGY: We searched MEDLINE, Embase, and CENTRAL (from inception to May 2025) for comparative studies of any design recruiting adults undergoing living or deceased donor kidney transplantation (PROSPERO CRD42023391473), that examined intraoperative IV UFH as a perioperative intervention. Study quality was assessed using the Newcastle Ottawa Scale.

OUTCOMES: Graft thrombosis (including subgroup analysis of arterial thromboses), bleeding complications, delayed graft function, and transplant nephrectomy. Relative and absolute effects were synthesised using a random-effects model as risk ratio (RR) with 95 % confidence intervals (CI). Certainty of evidence was assessed using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach.

RESULTS

Three retrospective cohort studies (1989 participants) met inclusion criteria. Study quality was rated as 'fair' in two studies and 'good' in one study. There was no difference for graft thrombosis with intraoperative IV UFH (3 studies, 1989 participants, RR 1.02, 95 % CI 0.49-2.12, I2 = 0 %, very low certainty evidence). Sub-group analysis also did not identify any difference for arterial thrombosis risk. Nearly all graft thromboses (17/23) resulted in transplant nephrectomy. IV UFH did not increase bleeding complications (3 studies, 1989 participants, RR 1.29, 95 % CI 0.78-2.13, I2 68 %, very low certainty evidence). There was no difference in delayed graft function (2 studies, 461 participants, RR = 0.95, 95 % CI 0.57 to 1.58, I2 = 40 %, very low certainty evidence).

CONCLUSION

Despite its common use in clinical practice, evidence supporting intraoperative IV UFH during kidney transplant surgery is sparce and of very low certainty. Current evidence does not demonstrate a reduction in graft thrombosis or delayed graft function demonstrated with intraoperative IV UFH, nor a clear increase in bleeding complications. High-quality prospective studies are needed to clarify the net clinical benefit of intraoperative UFH in kidney transplant surgery.