Early Postoperative Renal Vein Stenosis after Renal Transplantation: A Report of Two Cases

Contrast-enhanced US in Renal Transplant Complications: Overview and Imaging Features

Renal transplant is the first-line treatment of end-stage renal disease. The increasing number of transplants performed every year has led to a larger population of transplant patients. Complications may arise during the perioperative and postoperative periods, and imaging plays a key role in this scenario. Contrast-enhanced US (CEUS) is a safe tool that adds additional value to US. Contrast agents are usually administered intravenously, but urinary tract anatomy and complications such as stenosis or leak can be studied using intracavitary administration of contrast agents. Assessment of the graft and iliac vessels with CEUS is particularly helpful in identifying vascular and parenchymal complications, such as arterial or venous thrombosis and stenosis, acute tubular injury, or cortical necrosis, which can lead to graft loss. Furthermore, infectious and malignant graft involvement can be accurately studied with CEUS, which can help in detection of renal abscesses and in the differentiation between benign and malignant disease. CEUS is also useful in interventional procedures, helping to guide percutaneous aspiration of collections with better delimitation of the graft boundaries and to guide renal graft biopsies by avoiding avascular areas. Potential postprocedural vascular complications, such as pseudoaneurysm, arteriovenous fistula, or active bleeding, are identified with CEUS. In addition, newer quantification tools such as CEUS perfusion are promising, but further studies are needed to approve its use for clinical purposes. ©RSNA, 2024 Supplemental material is available for this article.

Biopsy Induced Arteriovenous Fistula and Venous Stenosis in a Renal Transplant

Renal transplant vein stenosis is a rare cause of allograft dysfunction. Percutaneous stenting appears to be safe and effective treatment for this condition. A 56-year-old Caucasian female with end stage renal disease received a deceased donor renal transplant. After transplant, her serum creatinine improved to a nadir of 1.2 mg/dL. During the third posttransplant month, her serum creatinine increased to 2.2 mg/dL. Renal transplant biopsy showed BK nephropathy. Mycophenolate was discontinued. Over the next 2 months, her serum creatinine crept up to 6.2 mg/dL. BK viremia improved from 36464 copies/mL to 15398 copies/mL. A renal transplant ultrasound showed lower pole arteriovenous fistula and abnormal waveforms in the renal vein. Carbon dioxide (CO₂) angiography demonstrated severe stenosis of the transplant renal vein. Successful coil occlusion of fistula was performed along with angioplasty and deployment of stent in the renal transplant vein. Serum creatinine improved to 1.5 mg/dL after.