vascular eval of organ transplants

allograft

any tissue transplanted from one human to another human

renal transplantation may be performed with:

• human leukocyte antigen (HLA) → matched deceased donors (DDs)

• HLA → matched living donors (LDs) that are either related or unrelated

survival outcomes are best for what type of renal transplants?

LD renal transplants

which kidney is preferred for harvesting?

the LT kidney because the renal vein is longer

where is the renal transplant typically placed?

in the right iliac fossa because the sigmoid colon limits space on the left

intraperitoneal renal transplant placement may occasionally be performed in what population?

in children

a portion of the aorta (a Carrel patch) as well as the entire renal artery is harvested for what type of renal transplant?

for DD renal transplants

during a renal transplant, the artery is anastomosed in an:

end-to-side fashion with the recipient’s external iliac artery

for LD renal transplants, the main renal artery is directly anastomosed:

end-to-side with the EIA or end-to-end with the IIA

during renal transplants, the main renal vein is anastomosed:

end-to-side to the external iliac vein

ureteroneocystostomy

the ureter is tunneled into the dome of the bladder superior to the native ureterovesicular junction (UVJ)

during a renal transplant, for urinary drainage, sometimes the ureter is connected to the bowel instead if there has been:

damage or tumor to the ureter

ureteral stenting

a stent is commonly placed in the ureter and usually removed after 2 weeks to 3 months

the ureteral stent decreases the chance of:

lymphocele formation and ureteral stricture

a baseline US evaluation is performed during what time period post-op?

in the first 24-48 hrs post-transplantation

what transducer is typically used to evaluate a transplanted kidney?

a high frequency transducer → 5 MHz

ultrasound evaluation of a renal transplant includes:

• renal size and echogenicity

• collecting system and ureter condition

• any post-op fluid collections

• color and spectral doppler of the renal and iliac vessels

• PSV and EDV of the intra-renal vessels

• measure the RI, PI and systolic/diastolic ratio

normal ultrasound findings of a renal transplant include:

• renal length may increase because of compensatory hypertrophy

• renal cortex is relatively echogenic

• medullary pyramids are more hypoechoic than a native kidney

• renal pelvic is usually slightly dilated

normal Doppler findings for a renal transplant include:

• color flow should be demonstrated throughout the kidney up to the renal capsule without areas of focal dilation

• PSV of intra-renal vessels may be elevated with an upper limit of 200-250 cm/sec

• sharp systolic peak and low-resistance waveform of intra-renal vessels

• RI for all renal arteries should be < 0.7 (> 0.8 is abnormal)

perfusion of the renal cortex of renal transplants should be:

symmetric and homogeneous throughout the transplant

transplant rejection

one of the most common causes of graft loss and is the result of attack by the immune system on the transplanted organ

what are the 3 types of renal transplant rejection?

1. hyperacute

2. acute

3. chronic

hyperacute transplant rejection

occurs immediately post-op because of the presence of antibodies to the allograft

acute transplant rejection

usually begins approx 2 weeks post-transplantation, with most cases occurring in the first 3 months

transplant rejection is suspected when one or more of the following clinical signs are detected:

• sudden cessation of urine output → anuria

• decreased urine output → oliguria → one of the earliest signs

• increased serum creatinine, protein, or lymphocytes in the urine

• HTN, or swelling or tenderness of the graft

vascular complications of a renal transplant include:

• acute tubular necrosis (ATN)

• focal renalinfarct

• renal vein thrombosis

• renal artery stenosis

• arteriovenous fistula (AVF)

• pseudoaneurysm

acute tubular necrosis (ATN)

most common cause of graft dysfunction in the immediate post-op period (2-3 days post op with most cases resolving within 2-3 weeks)

resolving ATN demonstrates:

improvement in diastolic flow and a normal RI

sonographic findings of ATN may include:

• renal enlargement

• decreased cortical echogenicity

• absence of diastolic flow or flow reversal → acute rejection

• elevated intrarenal RI → ATN, acute rejection

• decreased venous flow with severe acute rejection

• chronic rejection displays a decreased renal size, with a thinned echogenic cortex

focal renal infarct

• may be due to embolus, infection, or peri-procedural injury of the arterial wall

• an accessory main renal artery with a separate, small anastomosis may thrombose, causing a polar infarct

sonographic findings of focal renal infarct include:

• clear margins

• wedge or round shaped

• asvascular

renal vein thrombosis