Renal Transplant Duplex UltrasoundCriteria and Complications

Ann Marie Kupinski, PhD RVT RDMS FSVUNorth Country Vascular Diagnostics, Inc,

& Albany Medical College, Albany, NY

Objectives

Describe normal ultrasound findings of a renal transplant

List criteria used for renal transplants Identify commonly observed complications

Thanks to Bob DeJong for some images in this presentation

Renal Transplant Ultrasound

• Placed in the iliac fossa• Donor renal artery anastomosis

– Common iliac artery– External iliac artery

• Preferred • Donor renal vein anastomosis

– Common iliac vein– External iliac vein

• Preferred • Ureter anastomosis

– Superior lateral wall of bladder

Renal TransplantsTransplanted Renal Artery Stenosis

0-59% stenosis:• PSV < 250 cm/s without turbulence

60-99% stenosis:• PSV >250 cm/s with PST• Renal artery: iliac artery > 1.8

• Most common vascular complication (1-12%)• More common in LD than DD

Renal Transplants

Inflow Artery Stenosis0-50% stenosis:• Plaque without elevated velocities

50-99% stenosis:• PSV >200 cm/s with PST

Or • Doubling of the PSV

Renal Transplants

• Increased RI may indicate• Rejection, Acute tubular necrosis,

Nephrotoxic drug effects, Renal vein thrombosis, Extrinsic compression

• Normal RI 0.6-0.8

• Other complications include• Pseudoaneurysm, AVF• Extrarenal fluid collections

Renal Transplant Failure

Most common causes:– Acute tubular necrosis (ATN)

Occurs 2-3 days post-op Reported incidence 34% in DD transplants

– Rejection– Drug toxicity

Sonographic findings are nonspecific and unpredictable

Nonvascular Renal Transplant Complications

Hydronephrosis Fluid Collections

– Hematoma– Urinoma– Lymphoceles

Hematoma

–Post surgical, ubiquitous–Most are clinically insignificant–Some may decrease cortical

perfusion due to pressure (Page kidney)

–Resolve on their own–Perinephric in location–Echogenic becoming more

complex over time

Urinoma

Uncommon (1% incidence) Extravasation of urine from ureteral

anastomosis site– Occur within 2 weeks post-op

Clinical symptoms– Decreased urine output– Local tenderness– Fever if it becomes infected

Fluid collection between lower pole and bladder

Lymphocele

–Collection of lymphatic fluid –Incidence 0.5-20%–Manifests 4-8 weeks post-op–Multi-septated fluid collections by sonography

–May cause ureteric obstruction

–Drained or surgically removed

Vascular Complications

Incidence <10% Arterial stenosis Arterial thrombosis Venous thrombosis Post biopsy

– AVF– Pseudoaneurysm

Arterial Thrombosis

Occurs in immediate post-op period Rapid diagnosis needed for

thrombectomy or thrombolysis to save the transplant

More common in LD Incidence <1%

Cause of reversed diastolic arterial flow– Renal vein thrombosis

5% incidence Occurs 1st post-op week

– Severe ATN– Hyperacute rejection– Page Kidney (compression by

surrounding fluid)

Post Biopsy AVF Most small Clinically insignificant Spontaneously resolve

Post Biopsy AVF

Post Biopsy Pseudoaneurysmif >2 cm may require embolization

Conclusion

Renal transplant ultrasound is an important part of post-transplantation follow-up

Normal RA PSV<250 cm/s Normal renal:iliac artery <1.8 Various vascular and nonvascular complications can

be easily assessed with ultrasound