Urinary: Transplant Flashcards
Where is a kidney transplant usually placed?
Extraperitoneal iliac fossa (so it can be anastomosed with the external iliac vessels and urinary bladder)
What is the most important indication of a healthy renal transplant on ultrasound?
Resistive index below 0.7
Common urologic complications of renal transplant
- Obstruction
- Hematoma
- Urinoma
- Lymphocele
- Rejection
- Acute tubular necrosis
- Cyclosporin toxicity
Kidney transplant with mild hydronephrosis…
Normal finding
Note: Don’t call obstruction unless you see an obstruction, almost all kidney transplants have some mild hydronephrosis.
Where is the most common location for urologic obstruction in a renal transplant?
At the ureter-bladder dome anastomosis
Common causes of urologic obstruction in kidney transplants
- Post operative edema
- Scarring
- Technical errors leading to kinking
- Stones (less common, but still more common than in the general population)
When do urinomas tend to occur s/p renal transplant?
Within the first 2 weeks post op (usually at the ureter-bladder dome anastomosis)
Imaging test for post operative urinoma s/p renal transplant
- MAG3 renal scintigraphy
- CT with excretory images
- Ultrasound (cheaper)
When do lymphocytes tend to occur s/p renal transplant?
1-2 months after transplant
What is the most common fluid collection to cause transplant hydronephrosis after renal transplant?
Lymphocele
What causes a post renal transplant lymphocele
Leakage of lymph from lymphatic vessels (either due to surgical disruption or leakage in the setting of inflammation)
Fluid collection medial to a renal transplant with ipsilateral lower extremity edema…
Lymphocele
Note: Lower extremity edema due to femoral vein compression.
Treatment for post operative lymphocele s/p renal transplant
Usually nothing (they just come back)
Note: If treated, usually its done using a sclerosing agent.
What is the order of timing for the following complications s/p renal transplant: Abscess, Urinoma, Lymphocele, Hematoma
- Hematoma (within 1 week)
- Urinoma (~2 weeks)
- Abscess (weeks-months)
- Lymphocele (2 weeks-6 months)
How can you differentiate a postoperative urinoma from a lymphocele?
- Excretory phase CT
- Renal scintigraphy with MAG3 or DTPA
Note: Only a urinoma will show leakage of contrast/radiotracer outside the bladder.
How can you differentiate a post renal transplant hematoma from a urinoma/lymphocele?
Post operative hematomas happen earlier (within 1 week) and tend to be more complex (heterogeneous, septa, etc.)
Hyperacute renal transplant rejection
Immediate failure of the graft (rarely imaged)
When does acute rejection of a renal transplant usually occur?
Weeks 1-3
Note: Acute rejection is rare in the first 3 days.
Imaging findings of acute renal transplant rejection
- Edematous swelling of the graft
- Increasing resistive indices on Doppler ultrasound
How can you differentiate acute renal transplant rejection from acute tubular necrosis on imaging?
MAG3 renal scintigraphy can help:
In acute rejection, the whole study will be crap
In acute tubular necrosis, the flow and uptake portions of the study will be relatively normal, but there will be slow excretion
“Delayed graft function” in a renal transplant
Basically means the pt will need dialysis for the first week or so after transplant, but the graft will probably recover now that its getting blood again
Note: This is due to acute tubular necrosis that occurs between organ harvest and transplantation.
What is the most common time for cyclosporin toxicity to occur in a renal transplant?
Usually around 1 month post op (later than acute rejection 1-3 weeks post op and later than acute tubular necrosis)
MAG3 renal scintigraphy findings of cyclosporin toxicity
Relatively normal flow and uptake portions of the study, but delayed excretion
Note: This is the same as for acute tubular necrosis, but cyclosporin toxicity occurs later (not within a few weeks of transplant).
When does chronic renal transplant rejection occur?
Months to years after transplant
