Diagnostic ultrasound ( PDFDrive )

CHAPTER 9 The Kidney and Urinary Tract 369
the potential of Doppler as a primary screening modality.
Moreover, several recent trials showing no beneit of
revascularization/stenting over conservative, pharmacologic
antihypertensive management of renal arterial stenosis may impact
screening algorithms in the future. 283,284
Renal Artery Aneurysm
Renal artery aneurysms are saccular or fusiform dilatations of
the renal artery or one of its branches. he incidence of renal
artery aneurysm is 0.09% to 0.3%. 285 he cause may be congenital,
inlammatory, traumatic, atherosclerotic, or related to ibromuscular
disease. If the aneurysm is large (>2.5 cm), noncalciied,
or associated with pregnancy, the possibility of rupture increases
and treatment is recommended. At gray-scale sonography, a
cystic mass may be seen. he addition of duplex and color Doppler
imaging will readily demonstrate arterial low within the cystic
mass (Fig. 9.85).
Renal Vein Thrombosis
Renal vein thrombosis (RVT) usually results from an underlying
abnormality of the kidney, dehydration, or hypercoagulability.
Tumors of the kidney and let adrenal gland may grow into
the veins, resulting in RVT. Extrinsic compression related to
tumors, retroperitoneal ibrosis, pancreatitis, and trauma
cause RVT by attenuating the vessel and slowing low. In
adults the most common cause of RVT is membranous
glomerulonephritis; 50% of patients with this disease will
have RVT. If thrombosis is acute, the patient may have lank
pain and hematuria. Venous collaterals develop with more
chronic occlusion; patients with chronic RVT thus are oten
asymptomatic.
he sonographic features of acute RVT are nonspeciic and
include an enlarged, edematous, hypoechoic kidney with loss of
normal corticomedullary diferentiation. 286,287 Occasionally,
thrombus will be seen within the renal vein (Fig. 9.86), but acutely,
it may be anechoic and diicult to visualize. he use of duplex
and color Doppler ultrasound can help; however, the inability
to detect low within renal veins does not necessarily indicate
RVT. Extremely slow low oten will not be detected in diicultto-scan
patients despite optimized technique. Absent or reversed
end diastolic low in the intraparenchymal native renal arteries
is a secondary sign of RVT. Platt et al. 288 evaluated 20 native
kidneys in 12 patients with clinical indings suggestive of acute
RVT. hey found that normal arterial Doppler studies should
not prevent further workup if RVT is suspected (2 in 4 with
normal Doppler had RVT), and that absent or reversed diastolic
signals should not be considered speciic for RVT (2 in 10 with
absent or reversed diastolic low had RVT). If indings are
equivocal, MRI should be performed. Chronic RVT usually results
in a small, end-stage, echogenic kidney.
Ovarian Vein Thrombosis
Ovarian vein thrombosis is most commonly seen in postpartum
women, but it may also be seen as a result of pelvic inlammatory
disease, Crohn disease, or ater gynecologic surgery. he right
side is afected more oten than the let. Gray-scale, duplex, and
color Doppler sonography may reveal a long, tubular structure
illed with thrombus extending from the region of the renal vein
to deep within the pelvis. Patients are usually treated with
anticoagulation and antibiotics.
MEDICAL GENITOURINARY DISEASES
Patients presenting with elevated creatinine levels are oten sent
to the ultrasound department for an initial screening test. he
purpose is to rule out an underlying mechanical obstruction. If
A
B
FIG. 9.85 Renal Artery Aneurysm. (A) Color Doppler ultrasound image shows a distal right renal artery aneurysm. (B) Color Doppler of another
patient shows a peripherally calciied but thrombosed distal right renal artery (RRA) aneurysm.