“ Rejection In total, 90% show increased size of the kidney and large renal pyramids . Reduced corticomedullary differentiation. Most common...
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Rejection
In total, 90% show increased size of the kidney and large renal pyramids. Reduced corticomedullary differentiation. Most common cause of late graft loss.
US
• Reduction in central echoes
• Resistive index >0.7 (non-specific)
• Mild hydronephrosis
Nuclear medicine
• Reduced uptake of radiopharmaceutical
Renal artery stenosis
Affects up to 10%. Usually, stenosis occurs at the anastomosis/proximal graft artery. Segmental stenosis may occur in the setting of chronic rejection.
US
• Focal colour aliasing adjacent to stenotic segment
• Expect velocity >2 m/second, velocity gradient >2:1 across stenosis
Intervention
• Conventional angiography is reserved for stenosis confirmed on US or CT or clinical stenosis with normal US.
• May be treated with angioplasty/stent.
Pseudoaneurysm/arteriovenous fistula (AVF)
The result of biopsy, usually insignificant, unless large, when they may result in shunting and renal ischaemia.
US
• Focus of disorganised colour flow outside pattern of normal vasculature
• Draining vein may show arterialization (AVF)
Urinoma
Usually appears in the first month post-transplant, either from anastomotic failure or ischaemia.
• Non-specific fluid collection, fewer septations than haematoma
Nuclear medicine
• Persistent accumulation of radiotracer in the fluid collection
Abscess
Presents in the weeks post-transplant with fever and raised inflammatory markers.
US
• Complex fluid collection
Lymphocele
Usually presents between 1 and 4 months post-transplant in 10%-20% of recipients. Mostly inferomedial to the kidney. Mostly asymptomatic, but large collections may cause problems by direct pressure on the kidney/other structures.
• Rounded anechoic fluid collection, transplant hydronephrosis
• If leg swelling—check for deep vein thrombosis from pressure on external iliac vein.
Hydronephrosis
Mostly asymptomatic. Diagnosis made following deteriorating renal function. Mostly due to ischaemic stricture (usually at the vesico-ureteric junction [VUJ]—furthest from the transplanted renal artery).
US
• Dilated collecting system
• Echogenicity within the collecting system could be pus (pyonephrosis), blood, fungus balls or tumour
• Obstruction relieved with nephrostomy with or without stent
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