Diagnostic Ultrasound - Abdomen and Pelvis

Allograft Hydronephrosis
Diagnoses: Kidney Transplant
• More common from deceased donor transplants
Urothelial Thickening
• Secondary to acute rejection or infection
• Regular laminated wall thickening in renal pelvis or ureter
• If grossly thickened, can mimic hydronephrosis
Transitional Cell Carcinoma (TCC)
• Patients usually present with painless hematuria
• Hypoechoic urothelial tumor is solid with internal color
Doppler flow
• Typically causes hydronephrosis
Renal Sinus Cysts
• Peripelvic or renal sinus cysts may mimic hydronephrosis
• Differentiate by showing lack of communication between
cystic lesions and collecting system
Prominent Hilar Vessels
• Mimicking dilated ureter
• Easily differentiated from dilated ureter with aid of color
Doppler imaging
PATHOLOGY
General Features
• Etiology
○ Postoperative ureteral anastomotic edema and
denervation may cause transient early hydronephrosis
○ Fixed strictures of distal ureter and ureterovesical
anastomosis most commonly from ischemia, scarring,
surgical technique or rejection
– Distal ureter has tenuous vascular supply
○ Luminal causes of obstruction include blood clot,
calculus, sloughed papilla, or fungus ball
○ Extrinsic obstruction may be secondary to perigraft fluid
collections, fibrosis, or ureteral kinking
○ Reflux, infection, and decreased ureteral tone may cause
nonobstructive dilatation
• Associated abnormalities
○ Acute or chronic rejection
○ Infection
○ Hemorrhage
○ Nephrolithiasis (1-2%)
○ Urothelial tumors
Gross Pathologic & Surgical Features
• Early strictures typically secondary to ureteral ischemia or
surgical technical complication
• Later stenosis from rejection, drugs, or infection such as BK
infection
• Ureteral edema or intraluminal blood clot
• Cortical thinning if hydronephrosis is longstanding and
severe
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Rising creatinine level may prompt ultrasound
○ Diagnosis often incidental
• Other signs/symptoms
○ Rarely painful as allograft is denervated
○ Occasional tenderness, particularly if infected
○ Signs of infection
Demographics
• Epidemiology
○ Ureteral obstruction occurs in 3-6% of renal allografts
– Most common in first 6 months after transplantation
Natural History & Prognosis
• Ureteral strictures rarely lead to allograft loss if diagnosed
and treated promptly
Treatment
• Initial percutaneous nephrostomy to relieve obstruction
and until infection resolves
○ Antegrade nephrostogram to confirm diagnosis and
delineate location and length of stricture
○ Antegrade stent followed by balloon dilatation of
stricture
○ Retrograde stent and balloon dilatation more technically
challenging
• Surgical reconstruction required for long or recurrent
strictures
• Drainage of collections causing obstruction
• Removal of intrinsic obstruction such as clot, calculus
• Ureteral stent or Foley catheterization with bladder
irrigation for hemonephrosis
DIAGNOSTIC CHECKLIST
Consider
• Ultrasound is first-line imaging modality for renal transplant
dysfunction in immediate postoperative period or for
follow-up
• MR/MRU is complementary to ultrasound to evaluate
causes of obstruction
• Ultrasound-guided antegrade nephrostogram for initial
drainage and access for later interventional procedures
Image Interpretation Pearls
• Look for full bladder, stones, clot, or collections as potential
causes of hydronephrosis
SELECTED REFERENCES
1. Aktaş A: Transplanted kidney function evaluation. Semin Nucl Med.
44(2):129-45, 2014
2. Duty BD et al: The current role of endourologic management of renal
transplantation complications. Adv Urol. 2013:246520, 2013
3. Ferreira Cassini M et al: Lithiasis in 1,313 kidney transplants: incidence,
diagnosis, and management. Transplant Proc. 44(8):2373-5, 2012
4. Eufrásio P et al: Surgical complications in 2000 renal transplants. Transplant
Proc. 43(1):142-4, 2011
5. Cosgrove DO et al: Renal transplants: what ultrasound can and cannot do.
Ultrasound Q. 24(2):77-87; quiz 141-2, 2008
6. Kobayashi K et al: Interventional radiologic management of renal transplant
dysfunction: indications, limitations, and technical considerations.
Radiographics. 27(4):1109-30, 2007
7. Kamath S et al: Papillary necrosis causing hydronephrosis in renal allograft
treated by percutaneous retrieval of sloughed papilla. Br J Radiol.
78(928):346-8, 2005
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