Objectives

• Recognition, early evaluation, and management of kidney transplant recipients with allograft dysfunction due to vascular complications may be improved by earlier and standardized follow-up imaging protocols.
• Clinicians should be vigilant about the potential heightened risk of complications when multiple procedural interventions are performed simultaneously in high-risk kidney transplantation patients.
• Communication between teams during the management of kidney allograft dysfunction requiring procedural interventions is essential to reduce lag time in addressing further complications.

The Case

A 69-year-old man with End-Stage Kidney Disease (ESKD) secondary to diabetes mellitus and hypertension, who had been on dialysis since 2014, underwent deceased donor kidney transplant. He was discharged home on postoperative day (POD) 4 with slow graft function. His serum creatinine decreased postoperatively but began to increase about a month later. A kidney ultrasound showed increased vascular resistance (a marker of atherosclerotic and hypertensive organ damage), decreased diastolic flow, moderate hydronephrosis and a peri-transplant fluid collection. Magnetic resonance angiography (MRA) with ferumoxytol injection revealed kinking of the left external iliac artery (EIA) adjacent to the transplant anastomosis.

Based on these imaging findings, Interventional Radiology (IR) was consulted for a transplant nephrostomy tube placement, percutaneous drain placement, and angiography with possible stenting of the kinked left EIA. The nephrostomy tube placement and angiography were noted to be difficult, but the tube was placed and serial balloon angioplasty of the EIA was done. The patient had persistent low urine output and increasing creatinine. A kidney ultrasound on post procedure day (PPD) 3 revealed a central hematoma, decreased systolic velocity and no diastolic flow. Computed tomography (CT) of the abdomen and pelvis was concerning for renal artery thrombosis. He underwent a transplant nephrectomy, which also found a large capsular hematoma. A strong EIA pulse was noted after nephrectomy. He was discharged home on POD 4, but on POD 9, during a clinic visit, the patient reported increasing left leg weakness/heaviness and claudication. His left leg was cool with absent pulses. The patient was readmitted and CT angiogram revealed a left EIA dissection and stenosis. The vascular surgery team then performed a right to left fem-fem bypass. The patient was recovering well when he left against medical advice 3 days later.

The Commentary

By Nandakishor Kapa, M.D., and José A. Morfín, M.D.

This case demonstrates the complex nature of management of allograft dysfunction due to vascular complications in a patient with a deceased donor kidney transplant in the early post-transplant period. The patient initially had slow graft function with decreasing creatinine; however, his post-transplant laboratory tests after the first month demonstrated an increase in creatinine, which is concerning for graft dysfunction. The post-transplant period can be practically divided into the early post-transplant period, the first 3 months after transplant when more acute events occur, and the later post-transplant period, which is often more stable.¹ In the early post-transplant period, patients may present with increasing creatinine or decreased urine output (oliguria) that are concerning for acute graft dysfunction due to surgical or nonsurgical complications of kidney transplantation. Post-transplantation evaluation of graft dysfunction should include early efforts to rule out vascular and urologic causes by utilizing imaging studies, as early identification of surgical complications allows for expedient differentiation from medical complications such as rejection.

Kidney allograft ultrasound with Doppler is often the initial imaging used to evaluate possible surgical complications after kidney transplantation including urinary obstruction, transplant renal artery stenosis, and perinephric fluid collections (urinary leak, lymphocele, perinephric hematoma, etc.). Early vascular complications that can occur within a week of transplant include vascular thrombosis, which may occur with (secondary thrombosis) or without (primary thrombosis) immune rejection. Allograft primary thrombosis is rare (0.5-2 percent) and usually causes graft loss.² Most surgical complications involve either the wound, or one of the three anastamoses (renal artery, renal vein, or ureter), and thrombosis can result from technical problems such as intimal dissection or arterial or venous kinking.³ Many of these causes of allograft dysfunction can be diagnosed with ultrasound; therefore, practice guidelines recommend using ultrasound to narrow the differential diagnosis, which includes venous thrombosis, arterial occlusion, urine leak, urinary obstruction, and compressing perinephric hematoma.⁴ Even some potential causes of allograft dysfunction, such as hydronephrosis, stones, and cysts, can be identified in the post-transplant period by screening with ultrasound before they lead to acute allograft dysfunction.⁵

Despite the utility of ultrasound, transplant kidney ultrasound with Doppler is not a universal standard postoperatively and its use varies across transplant centers. Therefore, the decision to obtain an early postoperative ultrasound is usually driven by high-risk features of the patient, such as anatomic anomalies, or transplant operation, such as intraoperative technical challenges. Slow graft function alone, as in the patient in this case, has not traditionally been a factor that prompts early postoperative ultrasound.

In this case, the patient’s slow graft function in the immediate post-transplant period did not necessitate post-transplant imaging, as there was some function of the transplanted kidney. His worsening creatinine at one month, however, did appropriately lead to transplant kidney ultrasound, which revealed increased vascular resistance and obstruction. The subsequent MRA identified kinking of the EIA that was likely a result of a technical problem during the transplant procedure. There was delayed identification of the kinked EIA as it did not cause immediate post-transplant complications and was not noted intraoperatively. His persistently worsening kidney function despite nephrostomy tube placement to address the hydronephrosis, and angioplasty of the EIA to address the arterial kinking, should have indicated to the teams caring for the patient that a procedural complication may have occurred. However, the follow up ultrasound was delayed and not performed until 3 days later. This ultrasound identified a hematoma that was likely related to the radiology procedure as well as decreased flow that was ultimately attributed by CT to renal artery thrombosis. The renal artery thrombosis occurred most likely as a result of unsuccessful angioplasty to treat the kinked EIA. While the patient appropriately underwent transplant nephrectomy for renal artery thrombosis and had a strong EIA pulse after nephrectomy, there was an additional delay in diagnosis of his symptomatic leg weakness, coolness, and lack of pulses due to left EIA dissection and stenosis. The EIA dissection necessitating bypass surgery was likely an additional complication of the balloon angioplasty to address the kinked EIA. While arterial dissection is a known complication of balloon angioplasty, close evaluation during and after nephrectomy may have prevented the ultimate need for bypass surgery.

Approach to Improving Safety

Safety in management of kidney transplant patients in the early post-transplant period can be improved with standardized assessments for post-transplant vascular complications and improved communication between teams managing complications that may arise in the early post-transplant period. With current varying thresholds for obtaining transplant kidney ultrasound on post-transplant patients, common surgical complications can be missed if not identified during the initial transplant operation, leading to a delayed diagnosis. This patient’s case demonstrated potential areas for improvement in safety, as earlier transplant kidney Doppler ultrasound (i.e., immediately post-transplant) may have identified features that would have led to earlier confirmatory imaging with magnetic resonance angiography, which ultimately revealed the kinking of the left external iliac artery. Earlier diagnosis of this condition would have allowed for more prompt interventions with lower procedural risk. After nephrostomy tube placement and serial balloon angioplasty of the kinked EIA, the patient’s transplant kidney function did not improve as expected. The critical 3-day delay in obtaining repeat ultrasound imaging and subsequent CT imaging delayed the diagnosis and management of the renal artery stenosis that ultimately necessitated nephrectomy. Additional deficiencies in monitoring after nephrectomy led to further complications requiring arterial bypass surgery. A team leader, such as the transplant surgery or transplant nephrology services, at this time with an acute awareness of the patient’s overall clinical course may have realized these delays and taken ownership to address the lack of improvement in kidney function sooner. Communication between the interventional radiology, transplant surgery, and transplant nephrology teams co-managing the patient, and shared understanding of the expected timing of improvement in kidney function, may have prompted earlier non-invasive imaging with ultrasound. With multiple subspecialists involved in a patient’s care, it may be prudent to designate a team leader to oversee the entire course of care for a patient to avoid missing critical periods of monitoring.

Systems Change Needed

While the complications occurring in the post-transplant management of this patient may appear to be unique, system level changes may have prevented some of the complications that this patient experienced. Some of these potential changes include lowering the clinical threshold for imaging assessment of post-transplant patients, staging interventional procedures to reduce risk, and improving post-procedural communication. With lower thresholds for imaging and more frequent ultrasounds early in the post-transplant period, many common vascular and obstructive etiologies of graft dysfunction can be identified without the risk of delayed diagnosis further exacerbating complications. With the cumulative risk of complications from multiple simultaneous procedures by interventional radiologists, as demonstrated in this patient’s case, staging with interim imaging may minimize the risk. When patients such as the individual in this case do need multiple interventions, it is essential to ensure frequent communication between the teams, whether by decreasing lag time in documentation or through direct conversations about possible adverse outcomes and post-procedural monitoring.

Take-Home Points

• Recognition, early evaluation, and management of kidney transplant recipients with allograft dysfunction due to vascular complications may be improved by earlier and standardized follow-up imaging protocols.
• Clinicians should be vigilant about the potential heightened risk of complications when multiple procedural interventions are performed simultaneously in high-risk kidney transplantation patients.
• Communication between teams during the management of kidney allograft dysfunction requiring procedural interventions are essential to reduce lag time in addressing further complications.

Nandakishor Kapa, MD, MPH
Clinical Nephrology Fellow
Department of Internal Medicine, Division of Nephrology
University of California, Davis Medical Center

José A. Morfín, MD
Health Sciences Clinical Professor
Department of Internal Medicine, Division of Nephrology
University of California, Davis Medical Center

References

1. Danovitch GM. Handbook of Kidney Transplantation, Sixth Edition. Philadelphia, PA: Wolters Kluwer; 2017. ISBN: 978-1-49-632615-7
2. Leong KG, Coombs P, Kanellis J. Renal transplant ultrasound: the nephrologist's perspective. Australas J Ultrasound Med. 2015;18(4):134-142. Free full text
3. Humar A, Matas AJ. Surgical complications after kidney transplantation. Semin Dial. 2005 Nov-Dec;18(6):505-10. Available at
4. Kidney Disease: Improving Global Outcomes (KDIGO) Transplant Work Group. KDIGO clinical practice guideline for the care of kidney transplant recipients. Am J Transplant. 2009 Nov;9 Suppl 3:S1-155. Free full text
5. Chiang YJ, Chu SH, Liu KL, et al. Kidney ultrasound is useful tool in posttransplant follow-up. Transplant Proc. 2006 Sep;38(7):2018-9. Available at