Vesicoureteral Refl ux 331
24 Vesicoureteral Reflux
Emilio Quaia
E. Quaia, MD
Department of Radiology, Cattinara Hospital, University of Trieste, Strada di Fiume 447, Trieste, 34149, Italy
ureteral reflux in girls, the follow-up in boys, and in the management of recurrent infection in children presenting with normal radiological voiding cysto- urethrography (Galloy et al. 2003).
Further studies have proved the efficacy of void- ing sonocystography to detect and grade vesicoure- teral reflux also in adult patients who had undergone renal transplantation with previous evidence of uri- nary tract infection (Kmetec et al. 2001; Valentini et al. 2004).
24.1.1 Technique and Clinical Results
The bladder is emptied after aseptic introduction of a 5- to 8-F infant feeding tube. The bladder is then filled with 200–250 ml of room-temperature saline solution. Microbubble-based contrast agent is administered in a volume of 10% of the bladder volume (Valentini et al. 2004). After microbubble administration, a suspension of a small volume of saline solution is injected in order to push the resid- ual contrast agent through the catheter. In this way, echogenic microbubbles are easily identified in the bladder, which is filled by anechoic saline solution (Fig. 24.1). Harmonic imaging, gray-scale dedicated contrast specific techniques, or pseudo-Doppler contrast specific techniques including stimulated acoustic emission (Riccabona et al. 2003) need to be employed to detect microbubbles.
The microbubbles first reach the ventral region of the bladder creating a posterior strong acoustic shadowing and obscuring the dorsal region of the bladder. By increasing slowly the acoustic power of insonation, microbubbles are distributed into the vesical lumen. Then, acoustic power is switched at the lowest level (mechanical index: 0.04–0.2) to get a satisfactory visualization of microbubbles.
During microbubble administration, the blad- der, ureter, renal pelvis and calyces are evaluated by color or contrast-specific harmonic US modes.
The same evaluation is repeated during the void- ing phase.
CONTENTS
24.1 Introduction 331
24.1.1 Technique and Clinical Results 331 References 334
24.1
Introduction
Vesicoureteral reflux is the most common uri- nary tract abnormality in children, with a 1%–2%
incidence in the general population (Ascenti et al. 2004; Valentini et al. 2004), and 30%–50%
incidence in children with multiple episodes of urinary tract infections. Even though traditional retrograde voiding cystourethrography or radio- nuclide cystography still remain the reference standard techniques, contrast-enhanced voiding sonocystography now appears as a valuable alter- native method, due to the absence of radiation dose and the properties of microbubble-based contrast agents (Mentzel et al. 1999; Darge et al. 2001;
Valentini et al. 2004).
Recently, contrast-enhanced voiding sonocys- tography has been proposed both for the diagnosis and follow-up of vesicoureteral reflux in children (Darge et al. 1999; Ascenti et al. 2004). Several studies have shown the high diagnostic accuracy of contrast-enhanced voiding sonocystography com- pared to voiding cystourethrography (Berrocal et al. 2001; Valentini et al. 2001) and direct radionu- clide cystography (Ascenti et al. 2003) to detect and grade (Darge and Troeger 2002) vesicoureteral reflux in children.
Because of its accuracy, contrast-enhanced void-
ing sonocystography may replace radiological void-
ing cystourethrography in the detection of vesico-
332 E. Quaia
Fig. 24.1. Normal appearance of the bladder (arrows) previ- ously fi lled by microbubble-based agents in a 5-month-old boy. (Image courtesy of Dr. G. Ascenti)
Fig.24.2. A 2-month-old girl with a grade I vesicoureteric refl ux.
Bladder fully distended by microbubble-based contrast agent.
Minimal vesicoureteric refl ux (arrow) into the terminal left ureter.
[Reproduced with permission from Ascenti et al. (2004)]
Fig. 24.3a,b. Vesicoureteral refl ux diagnosed on the basis of echoes refl uxing from the bladder to the ureter, renal pelvis, and renal calyces. Renal pelvis and calyces (arrow) present no (a) or marked (b) dilatation. The case in Fig. 24.3a was classifi ed as grade II vesicoureteric refl ux. [Reproduced with permission from Ascenti et al. (2004)]
a b
Diagnosis of vesicoureteral reflux is assigned on the basis of echoes refluxing from the bladder to the ureter (Fig. 24.2), renal pelvis, and renal calyces (Fig. 24.3) or when color signals are seen in the uri- nary tract (Valentini et al. 2004). The associated morphologic signs (dilated or nondilated ureter, renal pelvis and calyces) contribute to vesicoure- teral reflux assessment with the use of five grades assigned on the basis of contrast-enhanced void- ing sonocystography (Valentini et al. 2001, 2004), which makes this system comparable to the most frequently used radiographic system of vesicoure- teral reflux grading (Lebowitz et al. 1985).
Grade I (Fig. 24.2), echoes or color signals in the ureter above the ureteral orifice; grade II (Fig. 24.3a), echoes or color signals extending up to the renal pelvis and calyces, with no ureteral dilata- tion; grade III, ureter, renal pelvis, and calyces con- taining echoes or color signals, with mildly dilated ureter (Fig. 24.4); grade IV, echoes or color signals in dilated ureter, renal pelvis and calyces (Fig. 24.5);
grade V, echoes or color signals in markedly dilated ureter, renal pelvis and calyces (Fig. 24.6).
Transperineal US was proposed as an imaging modality for studying urethral pathology and the bladder neck (Fig. 24.4c), and thus may complement voiding sonocystography (Mate et al. 2003).
Sensitivity and specificity of contrast-enhanced voiding sonocystography in revealing vesicoureteral reflux in children range from 69% to 100% and from 87% to 100%, respectively (Escape et al. 2001; Darge et al. 2001; Valentini et al. 2002, 2004; Ascenti et al. 2003; McEwing et al. 2003; Nakamura et al.
2003; Uhl et al. 2003; Vassiou et al. 2004).
Vesicoureteral Refl ux 333
Fig. 24.4a–c. A 12-month-old boy with grade III vesicoureteral refl ux. a Refl ux of microbubbles in a moderately dilated left ureter (arrows). b Evidence of microbubbles in the pelvicaly- ceal system (arrow) which is not dicated. c Transperineal US, complement of voiding sonography. Normal appearance of the urethra (u) and the bladder neck (arrow) after microbub- bles administration by employing the transperineal acoustic window. [Reproduced with permission from Ascenti et al.
(2004)]
a
b
c
Fig. 24.5a,b. A 4-month-old girl with duplex kidney and a grade IV refl ux- ing in the lower renal pelvis. a Refl ux of microbubbles in a moderately dilated left ureter (arrow). b Refl ux (arrow) of microbubbles into lower two-thirds of the renal pelvis which appears moder- ately dilated. [Reproduced with permis-
sion from Ascenti et al. (2004)] b
a
334 E. Quaia
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Fig. 24.6a,b. A 12-month-old boy with a grade V vesicoureteral refl ux. a Refl ux of microbubbles in a markedly dilated left ureter (arrow). b Evidence of microbubbles in the dilated renal pelvis and calyceal system (arrows). [Reproduced with permission from Ascenti et al. (2004)]
a b
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