Diagnostic ultrasound ( PDFDrive )

CHAPTER 52 The Pediatric Urinary Tract and Adrenal Glands 1803
A B C
FIG. 52.42 Normal Intrarenal Circulation in a 3-Year-Old Boy. (A) Longitudinal color Doppler sonogram shows the segmental vessels at
the hilum, the interlobar vessels alongside the pyramids, and the arcuate vessels at the inner edge of the cortex. (B) Spectral display from a normal
interlobar artery (low resistance, high diastolic low) and vein (pulsatile, relecting right atrial pulsations). (C) Power Doppler sonogram displays
blood low extending to the periphery of the renal cortex.
Normal
has the same result. Finally, signiicant compression from a
hematoma, lymphocele, or the tight abdominal wall around an
adult kidney transplanted into a small child can also cause
compression of vessels and decrease intrarenal arterial low.
he successful Doppler examination of intrarenal arteries
therefore includes the following two steps:
1. Comparing the RI with either the RI on the other side or the
RI from a previous examination
2. Reviewing the pertinent pathophysiologic factors involved
in a patient with high RI
Causes of Increased Resistive Index in
Renal Arteries
Compression
INTRAVASCULAR
Vascular spasm in shock
Endothelial inlammation in hemolytic-uremic syndrome
PERIVASCULAR
Intrarenal edema
Renal vein thrombosis
Acutely obstructed ureter
Endoluminal lesion
FIG. 52.43 Causes of Increased Resistance to Intrarenal Arterial
Flow.
intravascular, perivascular, and perirenal (Fig. 52.43). Any decrease
in the size of the lumen of small intrarenal arteries or arterioles
(spasm, as in shock; endothelial inlammation, as in hemolyticuremic
syndrome [HUS]) leads to increased resistance to arterial
inlow. Compression of small vessels by intrarenal edema (e.g.,
secondary to renal vein thrombosis) may result in identical arterial
Doppler tracings. Back pressure from an acutely obstructed ureter
PERIRENAL COMPRESSION
Hematoma
Lymphocele
Tight abdominal wall
Clinical Applications
Vessel Patency
he Doppler examination is a reliable indicator of the patency
of the renal arteries, of the veins, and of the presence of intrarenal
perfusion. herefore the examination is particularly useful in
the evaluation of renal allograt perfusion immediately ater
surgery. It is also useful in the exclusion of arterial injury ater
trauma, especially when the renal architecture is sonographically
normal and other, more invasive examinations are not indicated.