Transit-time flow measurement and high-frequency ultrasound for renal allograft vascular assessment

Abstract

Background: To describe arterial and venous flow and pulsatility index in renal allografts measured by transit-time flow measurement, anastomotic morphology assessed by intraoperative high-frequency ultrasound, and early outcomes after kidney transplantation.

Methods: This retrospective–prospective descriptive case series included 92 kidney transplant recipients at Military Hospital 175 from December 2024 to August 2026. Following reperfusion, arterial and venous flow and pulsatility index were measured using transit-time flow measurement; high-frequency ultrasound was used to select the anastomotic site and assess vascular morphology and patency. Early outcomes included intraoperative urine output, serum creatinine, estimated glomerular filtration rate, delayed graft function, and vascular reoperation.

Results: Mean age was 41.9 ± 9.8 years, and 66.3% were male. Multiple graft arteries occurred in 31.5% and two graft veins in 5.4%. Median arterial and venous flows were 558.5 mL/min (interquartile range, 446.2–712.8) and 426.0 mL/min (303.0–596.2), respectively; pulsatility indices were 1.00 (0.80–1.10) and 0.70 (0.50–1.00). No anastomotic stenosis, occlusion, or revision occurred. All grafts produced immediate urine. Median creatinine decreased from 629.7 to 99.7 µmol/L, while estimated glomerular filtration rate increased from 7.8 to 72.5 mL/min/1.73 m² by day 7 (p < 0.001). Arterial flow correlated positively with day-7 estimated glomerular filtration rate (ρ = 0.331; p = 0.001), whereas venous pulsatility index correlated negatively (ρ = −0.212; p = 0.042). No delayed graft function or vascular reoperation occurred.

Conclusion: Transit-time flow measurement and high-frequency ultrasound provided complementary intraoperative hemodynamic and morphological information. The absence of a control group and clinical events precludes causal inference or predictive threshold establishment.