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Journal de radiologie
Vol 79, N° 2  - mars 1998
p. 133
Doi : JRE-03-1998-79-2-0221-0363-101019-ART96
 

J Radiol 1998;79:133-7(in French)

© Editions françaises de radiologie, Paris, 1998

Original article

Voiding Cystourethrography Following a First Episode of Acute Pyelonephritis in young and adolescent girls.

C David, JN Dacher, M Monroc, D Eurin and P le Dosseur

Hôpital Charle Nicolle, service de Radiopédiatrie 1, rue Germont 76031 Rouen - France

Abstract

Despite its invasiveness, VCUG remains the examination of choice for detectingvesicoureteral reflux. The purpose of this study was to determine if VCUG is necessary inall girls following a first episode of acute pyelonephritis. A total of 152 patients wereretrospectively included in our study. The presence and grade of reflux decreased withincreasing age. US results poorly correlated with VCUG results for detection of reflux.Reflux was present in 30 patients older than 3 years, and was secondary in voidingdysfunction in 8. We suggest that voiding dysfunction could systematically be detected atclinical examination or with a simplified flowmetry study prior to performing VCUG.Because reflux is rarer after 9 years of age, VCUG should not be systematically performedfor patients in this age group.

Keywords: Vesicoureteral reflux. Children. Voiding cystourethrography. Voidingdysfunction.

Introduction

The main complication of urinary tract infections (UTIs) in children is secondary acutepyelonephritis (APN). Renal parenchymal involvement may lead to chronic scarring and, whenrecurrent, end-stage renal disease and arterial hypertension (1).

In children, renal involvement often is secondary to an underlying ureterovesicalabnormality, most commonly vesicoureteral reflux (VUR). Some authors advocate voidingcystourethrography (VCUG) in all patients after only one episode of infection (1).

In young adult women, primary APN is not uncommon and all patients are notsystematically evaluated for possible VUR (2, 3). The usefulness and yield of VCUG fordetecting VUR decrease as patients get older. However, there is no clear data from theliterature to indicate the age after which VCUG should not be systematically performed(4-6). At our institution, all patients in the pediatric age group are referred for VCUGafter a first episode of APN. In order to determine if VCUG should be performed in allpatients of pediatric age, we have looked at the yield of this examination in girls ofpediatric age since the disease is much more prevalent in this group of patients (7). Therole of US prior to VCUG and the significance of any associated voiding abnormality werealso analyzed.

Patients and Methods

The charts of all patients, aged 1 month to 16 years, admitted between January 1993 andAugust 1996 for a first episode of APN were retrospectively reviewed. APN was defined aspresence of fever ( 38.5 (C, abdominal pain, pyuria (( 10 leukocytes/mm3), pure urineculture ( 105/ml, and C-reactive protein ( 20 mg/l with leukocytosis (3). Fifteen patientshad no significant bacteriuria due to prior antibiotic administration (incompletelytreated APN) but were still included in the study because all other criteria were present.In 13 patients, APN was also confirmed on imaging studies: Power Doppler US (8) orcontrast-enhanced CT (9). All patients underwent US examination during the acute phase ofAPN and VCUG following recovery.

Patients with prior episodes of UTI, known VUR, or with other urinary problems(neurogenic bladder, UPJ obstruction, obstructive megaureter, kidney stone) were excluded.

Results of US were divided in 2 groups: suggestive or non-suggestive of VUR. Findingssuggestive of VUR included: fluctuating moderate ureteral or pelvicalyceal dilatation,asymmetry of renal size, poor corticomedullary differentiation.

VCUG examinations were performed with a digital fluoroscopy unit. For incontinentpatients, VCUG included 3 cycles (10): 3 consecutive fillings, 2 voiding with catheter, 1voiding without catheter. For continent patients, a single cycle was performed (1 filling,1 voiding without catheter). VCUGs were evaluated for the presence of VUR and its gradeaccording to the international classification (11), and also for the presence ofinterruptions during filling of the urinary bladder suggestive of abnormal contractions ordetrusor instability in a quiet patient (12, 13). During miction, several spot films(rapid sequence) were obtained to evaluate sphincter function.

Data collected from a review of the patients' charts included: age, presence ofinclusion criteria, and results of US and VCUG. Presence of clinical symptoms (urgency,frequency, dysuria/interrupted miction) and radiological findings (spinning-top urethra,trabeculated bladder, spasm of the external sphincter during miction, periureteraldiverticulum) suggestive of voiding dysfunction was recorded in all patients aged 3 yearsor more. Primary enuresis was not considered a voiding dysfunction. The incidence of renalscarring was not evaluated.

Results

A total of 152 patients were included. In this group of patients presenting with afirst episode of non-obstructive APN, 67 (44%) had VUR.

Ten of the 15 patients with incompletely treated APN had VUR.

Figure 1 shows the distribution of APN and VUR as a function of age. Three age groupswere defined: 1 month to 3 years old, 37 of 66 patients (56%) had VUR; 3 to 9 years old,27 of 62 (43.5%); 9 years and older, 3 of 24 (12.5%).

Table 1 shows the grade of VUR for each age group. VUR was of grade I in all 3 of 24patients older than 9 years of age.

A total of 30 patients older than 3 years of age had VUR. Twenty-three of these wereevaluated for the presence of voiding dysfunction; 8 had a voiding dysfunction. For theremaining 7 patients, there was no evidence in the chart that an evaluation for detectingvoiding dysfunction had been performed. Voiding dysfunction without VUR was present for 13patients.

Table II shows the results of US and VCUG for detecting VUR.

Discussion

In all age groups, UTI is the result of an imbalance between the host's defensemechanism and the virulence of the bacteria (2, 7). APN most often results from ascendinginfection from a lower UTI than from hematogeneous spread, except in the neonatal period.This is why neonates were excluded from our study.

The issue regarding etiologic factors involved in APN remains unsettled, and somecharacteristics of APN are specific to children (1). In the literature, VUR is reported tobe present in 30 to 40% of patients with UTIs (14, 15), and the prevalence of VURdecreases with age (5). In our study, VUR was present is slightly more than 44% ofpatients. This may be due to our imaging protocol which included a three cycle VCUG forinfants which increased our sensitivity (10).

The more frequent use of obstetrical US and the implementation of neonatal screeningfor VUR should lead to a decreased number of cases of VUR detected in the setting of UTI(16). However, in our study, correlation between the presence of US findings suggestive ofVUR and the presence of VUR on VCUG was poor (Table II). This may be due to the fact thatUS examinations were performed during the acute phase of PN and not following resolutionof symptoms. It is possible that US findings suggestive of VUR may have been obscured bythe inflammatory changes of APN. For example, presence of a smaller kidney secondary toVUR may have been obscured because of the relative renal enlargement seen with APN.

Absence of VUR of VCUG does not exclude ascending infection from a lower UTI. Somebacterial agents (E. coli p. fimbriae) may adhere to the urothelial wall (15, 17).

Classically, VUR is more common in patients with an abnormality at the vesicoureteraljunction (2, 6). Typically, the grade will progressively decrease and spontaneousresolution usually will occur by 2 to 3 years of age (Fig. 2) (6, 7, 18). Our resultsconfirm a decrease in the incidence of a first episode of APN with age, and a decrease inthe incidence of associated VUR in these patients.

VUR and APN are associated with chronic renal scarring which may lead to end-stagerenal disease and arterial hypertension. This risk is inversely proportional to the age ofthe patient and decreases significantly after 5 years of age (5, 14, 19). Therefore,screening for VUR should be more aggressive in younger patients. First line management ofpatients with VUR usually includes prophylactic antibiotic administration. Follow-up withradiographic or radio-isotopic cystography is performed until spontaneous resolution isdocumented or until surgical reimplantation of the ureters is considered. Initial surgicalmanagement rarely is performed except in patients with high-grade VUR, patients with VURand unilateral renal agenesis, or older patients with intermediate-grade VUR.

Is the risk/benefice ratio always in favor of VCUG in young and adolescent girls? Inour study, VUR was seen more frequently than would be expected from the natural history ofVUR.

Two hypotheses are possible:

- some cases of congenital VUR spontaneously resolve at an older age;

- certain factors may cause VUR to persist until 9 years of age, after which theincidence decreases (Fig. 1).

Urodynamic studies have shown that VUR could be secondary to increased intravesicalpressure in patients with sphincter dyssynergia (20). The notion of primary (congenital)reflux and secondary (acquired) reflux due to voiding dysfunction has emerged in theliterature over the last few years (6, 18). The syndrome of vesical immaturity is the mostfrequently observed etiology and usually occurs in girls aged 4 to 10 years but can beseen in patients up to 15 years old (21). It may result in sphincter dyssynergia as thechild attempts to overcome bladder contractions.

In our study, it seems that there was no relation between the presence or absence ofvoiding dysfunction and the presence of VUR. Voiding dysfunction was seen in only 8 of 23patients, but this number may be underestimated since all patients were not systematicallyevaluated for the presence of voiding dysfunction (21). It is important to distinguishprimary from secondary reflux since management of both conditions is different (6).Medical therapy (Oxybutinine and urine sterilization) sometimes associated with bladderre-education (biofeedback type) may result in resolution or decreasing grade of VUR (Fig.3) (20). Also, non-treatment of a voiding dysfunction may result in failure of surgicalcorrection (22). Screening for voiding dysfunction usually is performed clinically;urodynamic studies may be helpful in some patients. At our institution, we perform asimplified urodynamic evaluation that does not require insertion of catheters. Flowmetryis performed with surface electrodes over the perineum for EMG monitoring. In cases ofdetrusor instability, flowmetry and EMG are normal. In cases of sphincter dyssynergia,flow is decreased, the curve is dampened, and increased EMG activity is present duringmiction (Fig. 3). Following resolution of an episode of APN (often secondary to lowerUTI), this examination can be performed after clinical examination when voidingdysfunction is suspected. If dyssynergia is detected on flowmetry, VUR secondary toincreased intravesical pressure is probable, and VCUG confirmation may not be necessary. Atherapeutic trial of the voiding dysfunction may be performed. Indeed, voiding dysfunctionmay be related to psychological disturbances that are unlikely to be improved followingcatheterization of the bladder during VCUG! For example, VCUG may not have been necessaryfor the patient shown on Fig. 3.

When VCUG is performed, findings suggestive of voiding dysfunction should be noted.Abnormalities on VCUG can be detected in up to 95% of patients with sphincter dyssynergia(12, 13) and include : premature opening of the bladder neck during filling, small bladdervolume, trabeculated bladder, spinning-top urethra, with or without reflux, usually oflow-grade. The dynamic phase of VCUG is important (detection of interrupted bladderfilling).

The incidence of a first episode of APN decreases after 9 years of age (Fig. 1). VURalso is much rarer after that age (12.5%). Also, the psychological impact of bladdercatheterization and post-catheterization dysuria may be more important in adolescent girlsduring puberty. As such, VCUG should only be performed in selected cases such as patientswith recurrent infections. The incidence of APN also is reported to increase in sexuallyactive young adult women (2); this group of patients was not included in our study.

Conclusion

A prospective study could have provided stronger arguments than our retrospectivestudy. However, our results suggest that the usefulness of VCUG decreases with age inpatients presenting with a first episode of APN. Based on our results, we propose thefollowing indications for VCUG:

- VCUG should be performed in all patients younger than 5 years old due to the higherprevalence of congenital VUR and increased risk of renal scarring;

- between 3 and 9 years old, VUR may be secondary to a voiding dysfunction that can bediagnosed clinically and for which a specific therapy is required. We suggest thatflowmetry should be performed. VCUG could be performed when there is no suggestion ofvoiding dysfunction on flowmetry or when renal US suggests the presence of VUR. VCUGsshould always be evaluated for findings suggestive of voiding dysfunction such asinterrupted bladder filling;

- in patients older than 9 years of age, radiologic work-up could be similar to that ofyoung adult women (VCUG in the presence of US abnormalities, recurrent infection, or renalfailure).

In appears that the pathophysiology of APN in girls older than 9 years of age is quitesimilar to that in young adult women. In younger girls with voiding dysfunction, VCUGshould only be performed in selected patients and findings suggestive of voidingdysfunction recognized. VCUG should not be performed on all patients. Radiologists shouldbe familiar with findings suggestive of voiding dysfunction on VCUG. In all patients whereVUR is detected on VCUG, the reflux should be described as being primary and congenital orsecondary and functional.

Table I: Grade of VUR for each age group.

(Les tableaux sont exclusivement disponibles en format PDF).

 

 

Table II: US and VCUG results.

Total number of patients (patients with reflux)

(Les tableaux sont exclusivement disponibles en format PDF).



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