Diagnostic ultrasound ( PDFDrive )

338 PART II Abdominal and Pelvic Sonography
A
B
FIG. 9.40 Distal Ureteral Calculi. Sagittal sonograms of the distal ureters in two patients. (A) Calculus is 1 cm from the ureterovesical junction
(UVJ), with extensive edema of the distal ureteric mucosa. (B) Tiny calculus at UVJ with no obvious edema. Note posterior acoustic shadowing.
A
B
FIG. 9.41 Ureterovesical Calculus. Transvaginal sonograms in two patients show the value of this technique. (A) Small calculus obstructs a
mildly dilated ureter at UVJ. (B) Larger calculus with extensive surrounding ureteric edema.
peak systolic velocity–end diastolic velocity/peak systolic velocity).
It is believed that with obstruction, renal pelvic wall tension
increases, initially resulting in a short period of prostaglandinmediated
vasodilation. 109 With prolonged obstruction, many
hormones, including renin-angiotensin, kallikrein-kinin, and
prostaglandin-thromboxane, reduce vasodilation and produce
difuse vasoconstriction. Geavlete et al. 110 found that if there was
an intravesical ureteric jet on the renal colic side associated with
arcuate or intralobar RI values of 0.7 or less and diference between
renal RI values of 0.06 or less, spontaneous passage of the stone
occurred in 71% of cases. Platt et al. 108 used a threshold RI greater
than 0.70 to indicate obstruction, noting a diference in RI of
0.08 to 0.1 when comparing the patients’ obstructed and nonobstructed
kidneys. Initial reports advocating the Doppler
assessment of renal obstructive physiology were tempered by a
series of less promising studies. 101,109 he RI is largely dependent
on tissue/vascular compliance (diminished compliance results
in elevated RI, and vice versa) and driving pulse pressures, and
thus is not uniformly afected by obstruction. 111-114
Bladder Calculi
Bladder calculi most oten result from either stone migration
from the kidney or bladder stasis. Urinary stasis is usually related
to a bladder outlet obstruction, cystocele, neurogenic bladder,