Diagnostic ultrasound ( PDFDrive )

CHAPTER 18 Organ Transplantation 659
A
B
C
D
FIG. 18.42 Renal Artery Stenosis: Recipient Portion. (A) Color Doppler ultrasound shows focal area of aliasing (arrow) proximal to the renal
artery anastomosis. (B) Spectral Doppler of the region of aliasing seen in image (A) shows angle-corrected peak velocities of 400 cm/sec. (C)
Angiography shows a focal area of stenosis (arrow) arising from the external iliac artery. (D) Angiogram performed after angioplasty shows resolution
of the stenotic region (arrow).
narrowing indicates a hemodynamically signiicant stenosis 63
(Fig. 18.46).
Postrenal Collecting System Obstruction
Collecting system obstruction is unusual in renal transplants,
occurring in less than 5% of patients. 45,63 Because the allograt
is denervated, the collecting system dilates without clinical signs
of pain or discomfort. he diagnosis is oten made as an incidental
inding on routine screening sonography or in the workup of
the transplant patient for asymptomatic deterioration of renal
function parameters.
he most common cause of ureteral obstruction is from
ischemic strictures, usually involving the terminal ureter at
the ureterovesical junction. he transplanted ureter is particularly
susceptible to ischemic events because of its limited
vascular supply from the renal artery. he ureterovesical
junction is usually the region of most pronounced involvement
because it is farthest anatomically from the renal