Teaching Case

A 44-year-old man with end-stage renal failure underwent cadaveric kidney transplantation. On the immediate posttransplantation period good perfusion and diuresis were observed. During the first day after surgery, renal function impairment with oliguria supervened.

Doppler ultrasound performed on that day demonstrated globally diminished allograft perfusion and a parvus tardus spectral waveform both in the intra-renal vasculature and in the renal artery (Fig. 1) pointing to a proximal high-grade arterial inflow obstruction.

A conventional angiography was performed on the same day which demonstrated a filling defect on the medial aspect of the common iliac right artery, at the vascular anastomosis site, that led to distal severe arterial stenosis (Fig. 2).

The vascular anastomosis was revised surgically. The arterial obstruction was caused by a thrombosed dissection of the right common iliac artery as confirmed intraoperatively. The dissection was corrected surgically and perfusion regained.

The early postoperative period was complicated with a clinical and imaging picture compatible with acute tubular necrosis (Fig. 3), from which the patient recovered uneventfully.

Arterial dissection is a rare and serious complication of the early posttransplantation period. Early artery dissection risk of the renal transplant is related mainly with aspects of the surgical technique (e.g. anastomosis suturing technique, graft artery kinking, excessive traction of the graft artery during the harvest, cannulation for transplant perfusion, or surgical clamp).

Sudden oliguria with sonographic findings of decreased graft perfusion has a broad differential that includes vascular and parenchymal causes. Although differentiation among parenchymal abnormalities is usually made by percutaneous ultrasound-guided graft biopsy, this invasive diagnostic procedure cannot rule out vascular complications. In addition, acute rejection rarely develops in the first few days after transplantation. Therefore in this period, vascular complications should be much higher on the differential diagnosis list, and Doppler ultrasound complemented with angiography including graft venography should be the preferred diagnostic strategy.

Early diagnosis and treatment of vascular complications are of paramount importance for allograft salvage. If arterial dissection diagnosis is delayed, thrombosis supervenes rendering it less distinguishable from other forms of arterial obstruction and leading to graft loss.

Doppler ultrasound identifies renal graft ischemia, allowing noninvasive and timely triage for angiography. Ultrasound is an innocuous technique without exposure to iodinated contrast material and to its potential nephrotoxicity.

A parvus tardus spectral waveform indicates a proximal arterial inflow obstruction and should prompt additional investigation. Other data suggestive of proximal iliac artery stenosis include low pulsatility index (< 1.0), velocity greater than 200 cm/sec within the iliac artery proximal to the graft, and monophasic flow profile within the iliac artery distal to the transplant artery. Doppler sonography of a lower limb artery may be a simple way of confirming the diagnosis.

Although Doppler ultrasound provides evidence of vascular complications, it less often characterises its precise level and exact cause. Conventional angiography remains the gold standard in the definitive diagnosis and percutaneous treatment of vascular complications in this setting.

We report a rare case of renal allograft ischemia after iliac dissection in the early renal posttransplantation period, detected by correlative analysis of Doppler and angiographic findings. Differential diagnosis making and the appropriate imaging work-up strategy are emphasised, as well as the need for prompt diagnosis and treatment.
Therefore, although rare, iliac dissection is a potential correctable cause of renal allograft dysfunction that must be considered in the differential diagnosis of kidney failure in the early posttransplantation period.