Diagnostic Ultrasound - Abdomen and Pelvis

Approach to Sonography of Renal Allografts
pole when there are multiple supplying arteries. Intrarenal
veins are also documented but are less important.
Clinical Implications
Ultrasound is the method of choice for imaging renal
transplants. The most common indication is poor renal
function such as elevated creatinine and drop in urine output.
Other indications include fever, urinary tract infection, pain,
elevated white cell count, and dropping hemoglobin and
hematocrit. Occasionally, patients will present with swelling
over the graft or leakage from the wound. Hypertension and
bruit are later indications for ultrasound.
It is not possible to accurately diagnose rejection with
ultrasound. The main purpose of ultrasound is to exclude
other causes of renal dysfunction and facilitate ultrasoundguided
biopsy for the definitive diagnosis.
Ultrasound can accurately and promptly detect vascular
complications. It is the first-line imaging modality for
thrombosis, renal artery stenosis, and arteriovenous fistula
but may be limited by body habitus. Evaluation of arterial
aortoiliac inflow is best obtained with enhanced CT and MR if
renal function permits. Fluid collections and hydronephrosis
are readily detected but ultrasound is limited for infection and
tumor detection.
Complications of renal transplantation can be classified based
on timing since transplantation. Immediate complications
occur from the time of surgery to the first postoperative
week. The most frequent immediate complications are:
• Hemorrhage
• Graft thrombosis (arterial or venous)
• Delayed graft function/acute tubular necrosis/primary
graft non-function
• Hyperacute rejection
Early complications occur between 1 week and 1 month after
transplantation. These include:
• Acute rejection
• Drug toxicity (calcineurin inhibitors)
• Vascular complications: Graft thrombosis, post-biopsy
arteriovenous fistula or pseudoaneurysm
• Surgical complications: Ureteral leak or stricture;
perinephric hematoma, seroma, lymphocele; urinary
tract or systemic infection (can occur at any time)
Late complications are defined as occurring after 1 month.
The most common complications are:
• Complications of biopsy: Arteriovenous fistula and
pseudoaneurysm
• Ureteral stricture
• Renal artery stenosis
• Polyoma virus nephropathy
• Chronic rejection
• Malignancy: Post-transplant lymphoproliferative
disorder, renal and bladder cancer
Differential Diagnosis
It is uncommon for a specific diagnosis to be made from a
single ultrasound examination with exceptions such as renal
artery or vein thrombosis. In most patients, knowledge of the
clinical presentation and laboratory tests is essential for
narrowing the differential diagnosis and suggesting further
tests to the clinician.
Urothelial Thickening
• Infection
• Rejection
• Post relief of obstruction
• Secondary to stent
• Urothelial malignancy
Dilated Renal Pelvis
• Stricture
• Stone
• Extrinsic compression
Abnormal Blood Flow
• Arterial or venous thrombosis
• Arterial or venous stenosis
• Arteriovenous fistula
• Pseudoaneurysm
• Acute and chronic rejection
• Acute tubular necrosis
Fluid Collections
• Seroma
• Urinoma
• Lymphocele
• Hematoma
Poor Renal Function With Normal Ultrasound
• Acute tubular necrosis
• Acute and chronic rejection
• Drug toxicity
• Virus nephropathy
• Infection
Renal Transplant Mass
• Renal carcinoma
• Sloughed papilla
• Fungus ball
• Urothelial carcinoma
• Lymphoma
• Post-transplant lymphoproliferative disorder
• Infection: Non-liquefied abscess, granulomatous
infection
Selected References
1. Naesens M et al: Intrarenal resistive index after renal transplantation. N Engl
J Med. 370(7):677-8, 2014
2. Rodgers SK et al: Ultrasonographic evaluation of the renal transplant. Radiol
Clin North Am. 52(6):1307-24, 2014
3. Williams WW et al: Clinical role of the renal transplant biopsy. Nat Rev
Nephrol. 8(2):110-21, 2012
4. Cosgrove DO et al: Renal transplants: what ultrasound can and cannot do.
Ultrasound Q. 24(2):77-87; quiz 141-2, 2008
5. Irshad A et al: A review of sonographic evaluation of renal transplant
complications. Curr Probl Diagn Radiol. 37(2):67-79, 2008
6. Gao J et al: Intrarenal color duplex ultrasonography: a window to vascular
complications of renal transplants. J Ultrasound Med. 26(10):1403-18, 2007
Diagnoses: Kidney Transplant
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