Samir I. Saleh,
Mohamed M. Tohmaz, Fahed H. Al Anezi
Department of Pediatrics, Al-Jahra
Hospital, Kuwait
Fahad Alanezi,
MD
Department of Pediatrics
Al-Jahra Hospital, Kuwait
PO Box 4026, Z. code 01753
Tel: 965-4577213 Mob: 9659846919
Fax: 965-5640975, E-mail:
fdh529@hotmail.com
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ABSTRACT
Background:
Renal scarring is a serious but preventable
complication of urinary tact infection
(UTI) in children. The damage is usually
irreversible. However, not all children
with UTI and vesico-ureteric (VUR)
will develop scarring but the majority
of children with renal scars have
a history of UTI.
Objective: This
study was done to show the incidence
of renal scarring in children with
UTI with or without VUR.
Methods and results:
69 children, aged 1 year &
8 months to 8 years & 5 months,
with UTI were included in the study.
Urinary tract ultrasonography, voiding
cysto-urothrography and dimercapto-succinic
acid scan were done for all children
to detect urinary tract abnormalities,
vesico-ureteric reflux and renal scarring.
Renal scars were found in 15 children
(21.7%) and VUR in 23 out of 53 (43.4%).
All children were normotensive and
had normal renal function.
Conclusion: Renal
scarring should be looked for in all
children with UTI with or without
VUR.
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Key Words: Reflux
nephropathy, renal scarring, vesico-ureteric
reflux (VUR), urinary tact infection (UTI).
Urinary tract infection
(UTI) is a frequent problem in infants and
children. In Jahra area, the overall incidence
of UTI is 5.5% (1). Vesico-ureteral reflux
(VUR) has been reported in 35-40% of children
with UTI; and renal scarring may be seen
in 9.5-38% of those with reflux (2). In
children with a history of recurrent UTI,
renal scarring is even more common; it may
reach up to 25% (3, 4).
Renal reflux can result
in renal scarring, renal insufficiency,
rennin-mediated hypertension and end-stage
renal disease (5). There is abundant clinical
and experimental evidence that UTI and VUR
is important in the pathogenesis of renal
scarring (6, 7). Bacteria can reach the
kidney from the bladder by the reflux, especially
when bladder wall inflammation is co-existing,
leading to formation of cortical micro abscesses
and development of renal scars. However,
it has been shown that antibacterial treatment
can arrest or prevent the development of
scarring (8).
As reflux nephropathy
is irreversible, the objective of this study
was to determine the frequency of renal
scars and evaluate reflux in children with
established UTI attending Pediatric Outpatient
Department in Al-Jahra Hospital, Kuwait.
Sixty-nine children
with proved UTI were included in this study.
Sixty-seven were females and two were males.
Their ages ranged from 1 year and 8 months
to 8 years and 5 months. Details of presentation,
treatment and patient's and family history
were obtained. Further information was obtained
from parent's interview when necessary.
All underwent renal ultrasonography and
micturation cystourethrography (MCUG) as
a part of initial evaluation. Dimercapto
Succinic Acid (DMSA) scans were obtained
initially and 4-6 months after the last
episode of pyelonephritis. Grading of VUR
was based on the International Reflux Committee
classification (9). Renal Scars grading
was based on Goldarich and co-workers grading
system (10).
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All patients were
treated with appropriate antibiotic therapy
and remained on prophylaxis as indicated.
They were followed up and urine routine, urine
culture & sensitivity, renal function
tests, blood pressure measurements and growth
parameters were checked regularly.
Of the 69 patients who
did DMSA scan (Table 2),
12 had scars on initial diagnosis and 3
developed them 4-6 months later (21.7%).
Their ages ranged from one year and eight
months to eight years and five months. One
was male and 14 were females. The male patient
was circumcised. Forty-five patients (65%)
had history of recurrent UTI (Table
1). E.coli was the cause of infection
in all patients, except one who had Klebsella.
The scars were more common in the left kidney
(60%). In 11 patients the scars were in
the upper lobe of the kidney (73.3%) and
4 in the lower lobe (26.7%). Clinically
they were normotensive and had normal growth
and development.
Varying grades of vesico-ureteral reflux
(VUR) was detected in 23 patients out of
53 (Table 3), who did
MCUG (43.4%); 14 with grade I, 4 with grade
II, 3 with grade III and 2 with grade IV
reflux. Fourteen patients had bilateral
reflux and 9 had unilateral reflux. Reflux
grade 1, and scars stage I & III were
the most prevalent sequelae following UTI.
Of the fifteen children with renal scars
9 had VUR; 7 with grade I reflux and 2 with
grade II. Ultra-sound of abdomen showed
congenital anomalies in 3 (33.3%), one with
congenital polycystic kidney, one with congenital
multicystic kidney and the third with congenital
left hydronephrosis (Table
3).
Reflux nephropathy is
known to be a major cause of renal failure
in children. Renal scintigraphy with dimercaptosuccinic
acid (DMSA) is a valid diagnostic tool for
confirming the presence of acute pyelonephritis
as well as for documenting the presence
of renal scarring. Its sensitivity and specifity
are more than intravenous pyelography; IVP
(11&12). Only 40% of our patients with
proved renal scarring showed changes on
IVP. However, the routine use of DMSA scan
during the acute illness is not considered
necessary (13). In our study, 15 out of
69 studied children with UTI had renal scarring
(21.7%). Other authors showed different
results. Szlyk et al (14) found that 38%
of their patients had renal scars, while
Polito et al (15) reported 37%. The low
incidence of renal scarring in our cases
may be due to early treatment of our patients
as there is evidence that delay in diagnosis
and treatment of UTI can contribute to the
development of renal scarring (16 &
17).
Risks of hypertension
and chronic renal failure are higher with
diffuse scarring (18). Hadi et al (2) showed
that hypertension occurred in 7.1% of their
patients over a 6-year period. In our study,
none of our patients suffered from hypertension.
However, a long period of follow-up is necessary
to verify the occurrence of this complication.
Vesico-ureteral reflux
(VUR), has been identified as a risk factor
for the development of UTI and renal scarring.
Dick et al (2) showed that 62.5% of their
patients with VUR had renal scarring. Lana
et al (20) reported that 60% of girls and
44% of boys in the first year of life with
VUR and UTI had renal scarring. Others showed
similar results (21). In our study, only
9 patients out of 15 with renal scarring
(60%) had VUR (Fig. 1).
This proves that; although VUR is a risk
factor for development of renal scarring,
the lesion can still develop without VUR.
This may be due to intra-renal reflux facilitated
by the flat papillae in the kidney. Bacteria
can also reach the kidney through transient
reflux occurring with severe UTI and bladder
wall inflammation, or by binding to epithelial
cell surface in some children with specific
blood groups.
Radiologists often report
various degrees of dilatation of the collecting
system of the kidney in patients with UTI
on renal ultrasonography (22). However,
in our study the ultrasound findings were
not predictive of VUR and VCUG was necessary
to rule out VUR, regardless of renal ultrasound
findings. A similar conclusion was noted
by S Mahant et al (22). Davey and colleagues
(23), as well, found that the frequency
of VUR in children with mild renal pelvic
distension did not differ significantly
from that in children without distension
on renal ultrasound.
Our study suggests that
incidence of renal scarring is high (21.7%)
in children with UTI and that absence of
VUR is not protective, as renal scarring
can occur without VUR. We recommend early
diagnosis and aggressive treatment of children
with UTI. We also recommend performing DMSA
scan for all children with UTI, especially
in younger ages and in those with high grade
VUR.
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