Diagnostic ultrasound ( PDFDrive )

CHAPTER 18 Organ Transplantation 649
A
B
C
D
FIG. 18.30 Benign Renal Cysts in Four Patients. Sagittal sonograms of transplant kidneys. (A) Simple upper-pole cyst, which is avascular on
color Doppler ultrasound. (B) Upper-pole cyst with a single thin strand. (C) Milk of calcium cyst with dependent calciication. (D) Marsupialized
renal cyst (arrows) appearing as an echogenic mass.
Abnormal Renal Transplant
Renal transplants are routinely evaluated with sonography as
either a component of a screening protocol or a workup for renal
dysfunction based on a rising serum creatinine level or a decreased
urine output. Postoperative complications have been reported
in up to 20% of renal transplant recipients. 46 When encountered
in a grat with a clinical suspicion of dysfunction, the sonographer
should approach the possible causes in terms of (1) parenchymal
pathology, (2) prerenal causes, and (3) postrenal complications.
Parenchymal transplant pathology includes acute tubular necrosis
(ATN), acute and chronic rejection, and infection. Prerenal
problems include all factors afecting blood low to the kidney
or venous drainage from the grat. Postrenal complications include
intrinsic or extrinsic lesions that can obstruct either a component
of the calyceal system or the transplanted ureter.
Parenchymal Pathology
Acute Tubular Necrosis and Acute Rejection
Acute tubular necrosis results from donor organ ischemia either
before vascular anastomosis or secondary to perioperative