Renal
Abnormalities
in Schoolchildren
Chung-Pin
Sheih,
MD, Mong-Bing
Liu, MD, Cheng-Shen
Hung,
MD,
Kun-Hou
Yang,
MD, Wan-Yu
Chen,
MD, and
Ching-Yuang
Lin, MD, PhD
From the Departments of Pediatrics and Urology, Taipei Municipal Women and Children’s Hospital; Department of Internal Medicine, National Taiwan University Hospital; and Departments of Medical Research and Pediatrics, Veterans General Hospital, Taipei, Taiwan, Republic of China
ABSTRACT. To establish prevalence of some renal
ab-normalities in schoolchildren, an epidemiologic study of 132 686 schoolchildren, including 69 903 boys and 62783
girls, was conducted from March 1987 to May 1988 in
the city of Taipei. At the health station of each school,
the students were screened quickly by a physician with
portable real-time ultrasound equipment. When a renal
abnormality was detected or suspected, the examinee was
referred to Taipei Municipal Women and Children’s
Hos-pital for further investigation. Radiologic and urologic
procedures were then selectively performed to establish
the correct diagnosis. Renal abnormalities were detected
in 645 students (approximately 0.5% of total population
screened). There were 256 cases of hydronephrosis, 103
cases of unilateral renal agenesis, 128 cases of unilateral small kidney, 90 cases of renal cystic disorders, 30 cases of ectopic kidney, and 38 cases of other abnormalities. Surgically correctable lesions were demonstrated in 50 of these students. Rapid renal ultrasonography was found to effectively detect some renal abnormalities initially,
and prevalence could then be established after further
investigations. Pediatrics 1989;84:1086-1090; ultrasound screening, schookhildren, hydronephrosis, renal agenesis, renal cyst.
sonic instruments, more sophisticated and rapid
scanning of the kidney is possible. In an attempt to
elucidate the prevalence of schoolchildren’s renal
abnormalities in Taiwan, we created a simplified
nephrosonographic process to be used for initial
rapid screening. Radiation is not used in ultrasonic
imaging. The direct costs for rapid renal ultrasonic
screening are low. Therefore, we considered that
the rapid renal ultrasound examination with
port-able scanner would provide an excellent method for
initial detection of some renal abnormalities.
Prey-alence was then established after additional
diag-nostic procedures. If a large enough population is
screened, the data might reflect the more accurate
prevalence of some renal abnormalities in the
schoolchildren population. The goal of this study
was to establish prevalence of some occult renal
abnormalities in school-aged children by initially
screening with ultrasound.
MATERIALS
AND
METHODS
Urinary tract abnormalities are important
find-ings in pediatrics. In the past, the prevalence of
urinary tract abnormalities has been taken from
autopsy series or excretory urograms.’3 Recently,
Steinhart et al,4 as well as others,5’6 have observed
that significant “silent” urinary tract abnormalities
can be effectively detected by ultrasound screening.
Today, because of the technical advances in
ultra-Received for publication Oct 14, 1988; accepted Jan 23, 1989. Reprint requests to (C.-Y.L.). Pediatric Research Laboratory, Department of Medical Research, Veterans General Hospital, Shih-Pai, Taipei, Taiwan, 11217, Republic of China.
PEDIATRICS (ISSN 0031 4005). Copyright © 1989 by the American Academy of Pediatrics.
Study Population
From March 1987 to May 1988, 132 686
elemen-tary school and junior high school students in
Taipei city were screened. Their ages ranged from
6 to 15 years; 69 903 were boys and 62 783 were
girls.
Methods
A portable ultrasound scanner (General Electric
Company, model RT 50) was used for initial
screen-ing. The students were lined up at the health station
in the school. They were asked to lift their shirts
and were examined in standing position, one after
another, bending forward slightly at the waist. After
containing diluted jelly, the probe was placed on
the back region of the child. Both kidneys were scanned quickly. Each examination required
ap-proximately 15 to 20 seconds.
Renal sonographic assessment included (1)
shape, size, and contour of the kidney, (2) width,
homogeneity, and echogenicity of the renal
paren-chyma, and (3) status of the renal sinus. If a kidney
abnormality was detected by renal ultrasonic
screening, the child was referred to Taipei
Munic-ipal Women and Children’s Hospital for physical
examination and detailed renal sonography. To
confirm the diagnosis, further investigations were selectively performed, depending on the variety and severity of the renal abnormality. These tests
in-cluded urinalysis, blood urea nitrogen, creatinine,
creatinine clearance, serum electrolytes,
intrave-nous pyelography, diuretic urogram, radionucide
renal scan, diuretic radionuclide renogram T#{189},
an-tegrade pyelography, retrograde pyelography,
void-ing cystourethrography, cystic puncture,
cystos-copy, computed tomography, and renal biopsy.
De-tailed explanations and medical advice were given
to the students and their parents to relieve anxiety.
Hydronephrosis visualized by ultrasonic
exami-nation is classified as mild, moderate, or severe,
depending on changes in the renal structure.7’#{176} In
persons with mild hydronephrosis, renal
paren-chyma is normal and only slight pelvic dilation is
noted. In those with moderate hydronephrosis,
de-creasing thickness of the parenchyma and dilation
of both pelvis and calyces are noted. Severe
hydro-nephrosis is defined as fully dilated pelvis and
calyces, thin parenchyma, and enlarged renal
con-tour. To determine whether the lesion in children
with moderate and severe hydronephrosis was
ob-structive or nonobstructive, further investigations
including intravenous pyelography, diuretic
uro-gram, diuretic radionuclide renogram T#{189},antegrade
pyelography, voiding cystourethrography were
se-lectively performed.
Unilateral renal agenesis was strongly suspected
when a kidney was not observed in the renal fossa
during sonographic examination and the
contralat-era! kidney was compensatorily hypertrophied. A
99mTc dimercaptosuccinic acid scan and/or
intra-venous pye!ography were performed to confirm the
diagnosis.
A unilateral small kidney was suspected when
the difference in length between the two kidneys
was 1.5 cm or greater, and the smaller kidney was
less than nor ma! range.”2
The typical sonographic pattern of simple renal
cyst is an echo-free area with a thin proper wall
and an enhancement of the posterior interface.’3
Multicystic dysplasia was differentiated according
to Stuck’s criteria.’4”5 A Tc dimercaptosuccinic
acid scan was then performed to confirm the
diag-nosis. When bilateral multiple renal cysts and a
positive family history were noted, adult-type
poly-cystic kidney was suspected.16’17
An ectopic kidney was suspected’22 when the
kidney was not located in the renal fossa position.
Additional investigations, including detailed
ab-dominal sonography, intravenous pyelography,
and/or radionucide renal scan were performed to
locate the kidney.
Renal parenchymal diseases could be suspected
if renal echogenicity was markedly enhanced with
or without a contracted kidney.
RESULTS
There were 645 cases of renal abnormalities in
this series. The frequency of renal abnormalities
detected in 132 686 students was approximately
0.5%.
Hydronephrosis (39.6%) was the mostfre-quent renal abnormality found, followed by
unilat-eral small kidney (19.8%), unilateral renal agenesis
(15.9%), and renal cystic disease (13.9%) (Table 1).
There were 21 false-positive results; the initial
son-ograms suggested renal abnormalities but were
found to be normal when repeat studies were
per-formed. All patients were instructed to seek regular
follow-up in our clinic. Uropathologic conditions
severe enough to require surgical intervention were
detected in 50 children (0.037%); 45 of the 50
chil-dren received surgical correction, 43 of them
suc-cessfully.
The total cost of screening 132 686 students was
approximately $47 500 (US currency). In other
words, the individual expense was only about $0.36
per student (Table 2).
Clinically, most ofthe patients had no symptoms.
More than 90% denied any renal diseases in the
past. Vague intermittent abdominal discomfort was
the most common symptom, especially in patients
with obstructive hydronephrosis. The symptoms of
urinary tract infection that occur in early life are
easily neglected by older children and their parents.
Only a small group of patients with renal
abnor-malities, especially those with unilateral small
kid-neys, had previous urinary tract infections.
DISCUSSION
In the present study, the frequency of renal
ab-normalities was approximately 0.5%. However,
there were only 50 cases (0.037%) in the 132 686
students who required surgical treatment. This rate
is less than that of Steinhart et al (1.37% babies in
their series required surgery4). This difference may
be the result of age differences in the subjects
screened. During infancy, there are relatively more
TABLE 1. Renal Abnormalities
Renal Abnormalities No. of Abnormalities
Boys Girls Total (%)
Hydronephrosis 256 (39.6)
Mild hydronephrosis 129 57
Moderate and severe hydronephrosis
Nonobstructive type 16 13
Obstructive type
Pelviureteric obstruction 23 8
Retrocaval ureter 3
Ureteral stricture 1
Ureterovesical obstruction 4 2
Unilateral small kidney 94 34 128 (19.8)
Unilateral renal agenesis 56 47 103 (15.9)
Renal cystic diseases 90 (13.9)
Simple cyst 38 24
Adult polycystic kidney disease 3 3
Multicystic dysplasia 13 8
Multiocular cyst 1
Ectopic kidney 30 (4.6)
Thoracic kidney 1
Cephalad ectopia 1
Lumbar kidney 12 9
Pelvic kidney 4 1
Cross ectopic kidney 2
Horseshone kidney 9 7 16 (2.4)
Duplex kidney 2 5 7 (1.0)
Renal parenchymal disease 6 1 7 (1.0)
Neoplasm 1 1 (0.15)
Stone 2 2 (0.3)
Miscellaneous 4 1 5 (0.7)
TABLE 2. Cost of Ultrasound Screening (n = 132 686)
Cost (US Currency)
* Depreciation of the portable ultrasound scanner was
based on 5 years of useful life for frequent usage of a
scanner.
Salary for 15 mo
Physician ($2000/mo) 30 000
Assistant ($500/mo) 7 500
Supplies
Jelly (dilution with water) 2000
Record paper 1 000
Miscellaneous 5 000
Depreciation* 2 000
Total cost 47500
Cost/examination 0.36
junction obstruction, and spontaneous remission
during the growing period is not uncommon.
The results of this study suggest that there are a
significant number of asymptomatic children with
urinary tract abnormalities that can be detected by
relatively low-cost renal sonographic screening.
The individual expense was only about $0.36 per
student. After renal sonographic screening, 50
chil-then required surgical intervention to prevent renal
function deterioration. The cost of screening per
each detectable abnormality was $950 (47 500/50).
Therefore, the individual overall cost for screening
plus surgery was = $1950 per child with an
abnor-mality ($1000 + %1950, respectively). On the other
hand, when the disease progresses to uremia, the
dialysis fee for each patient is $15 600/y. Other
medical care fees for each patient would be
approx-imately $400. Thus, each patient requiring surgical
correction can save $16 000 ($15 600 + $400)
thanks to early detection by renal sonographic
screening. Therefore, for these patients the benefit
to cost ratio is approximately 8 (16 000/1950).
Al-though a unilateral lesion generally does not
pro-gress to uremia, the patient always has frequent
urinary tract infections. It is impossible to calculate
the benefit to cost ratio of early detection of renal
disease in these children, but, certainly, much
money was saved and future morbidity was
pre-vented.
In the present study, patients with mild
hydro-nephrosis were instructed to have long-term
follow-up by nephrosonography without radiologic
inves-tigation. Until now, all of these patients have been
stable and had no progression of their disease. In
patients with moderate and severe hydronephrosis,
further radiologic examinations were performed to
differentiate obstructive from nonobstructive
dis-ease. When obstructive uropathy was
demon-strated, early surgical intervention was suggested
We found the prevalence ofunilateral renal
agen-esis to be approximately 1 in 1290 children, which
is similar to that reported by others. According to
an autopsy series, unilateral renal agenesis occurred
in 1 of 1100 births.1 In a survey of excretory
uro-grams performed at the Mayo Clinic, the prevalence
approached 1 in 1500.2
We discovered five cases of genitourinary cystic
anomalies associated with ipsilateral renal agenesis
or dysplasia, including two cases of blind
uretero-cele, two cases of Gartner cyst, and one case of
seminal vesicle cyst. Three children had
experi-enced straining while urinating since early
child-hood, which was neglected by their parents. Four
cases were confirmed during surgery. Consequently,
we speculate that these conditions are not as rare
as previously described.24’ For early detection of
these anomalies in patients with unilateral renal
agenesis, pelvic sonography may be indicated.
Causes of unilateral small kidney usually include
hypoplasia, dysplasia, reflux nephropathy,
postob-structive atrophy, and vascular diseases.11 In this
study, many cases of small kidney could be
deter-mined by the renal contour, number and changes
of calyces, and status of reflux during intravenous
pyelography, voiding cystourethrography, and
radionuclide scan. In other cases, however, whether
the small kidney is hypoplastic, dysplastic,
hypo-dysplastic, or pyelonephritic can only be
deter-mined by histologic findings.’2
Only a few cases of simple renal cyst in children
have been reported previously.’3’2 However, in
the present study, the greater number of simple
renal cysts was noted. Most of these patients were
symptom free. Therefore, if the renal ultrasound
screening had not been done, these cases would
have remained undetected.
The detection of horseshoe kidney and duplex
kidney by rapid ultrasonic screening has its
limi-tations.m If only an asymmetric kidney is noted,
then horseshoe kidney is suspected. Therefore, only
16 cases were detected in the present study.
Duplex kidney may be suspected under the
fol-lowing conditions: (1) obstruction of the upper pole
moiety or reflux of the lower pole moiety in
com-plete duplication3 and yo-yo phenomenon in
in-complete duplication37 leading to hydronephrosis,
(2) a duplex kidney on one side manifests as a
unilaterally enlarged kidney, and (3) a renal sinus
separates into two parts. In the present study, three
cases of duplex kidney with the obstructed upper
pole moiety were detected, which included two cases
of ectopic ureter and one case ofectopic ureterocele.
In summary, although it has been said that
ultra-sonography is not sensitive enough to demonstrate
some renal abnormalities, especially small and mild
renal lesions, initial rapid renal ultrasound
screen-ing has provided a safe and effective way to detect
some obvious structural renal abnormalities, such
as unilateral renal agenesis, unilateral small kidney,
distant ectopic kidney, cystic renal disease,
con-tracted kidney, and hydronephrosis. In this study,
we used a nontraditional method to establish the
prevalence of some renal abnormalities such as
unilateral renal agenesis Boys had a greater
fre-quency of renal abnormalities than girls. Fifty
chil-then had surgically treatable diseases detected by
our method; most ofthese children had experienced
unexplained vague intermittent abdominal pain or
urinary symptoms. Therefore, initial sonographic
examination may be useful in school-aged children
with these symptoms.
REFERENCES
1. Doroshow LW, Abeshouse BS. Congenital unilateral solitary kidney: report of 37 cases and a review of the literature. Urol Surv. 1961;11:219-229
2. Longo VJ, Thompson GJ. Congenital solitary kidney. J UroL 1952;68:63-68
3. Kelalis PP. Anomalies of the urinary tract. In: Kelalis PP, King LR, Belman AB, ads. Clinical Pediatric Urology. ed 2. Philadelphia, PA: W B Saunders Co; 1985:643-672
4. Steinhart JM, Kuhn JP, Eisenberg B, Vaughan RL, Mag-gioli AJ, Cozza TF. Ultrasound screening of healthy infants for urinary tract abnormalities. Pediatrics. 1988;82:609-614 5. Helm I, Persson P-H. Prenatal diagnosis of urinary tract
abnormalities by ultrasound. Pediatrics. 1986;78:879-883 6. Colodny AH. In utero diagnosis of urinary tract
abnormali-ties. In: Retik AB, Cukier J, cdi. Pediatric Urology.
Balti-more, MD: Williams & Wilkins Co, 1987:370-383
7. Neuenschwander 5, Montagne JP. Urinary tract abnormal-ities. In: Kalifa G, ed. Pediatric Ultrasonography. Berlin,
West Germany: Springer-Verlag Co, 1986:142-17
8. Hayden CK, Swiachuk LE. Pediatric Ultrasonography. Bal-timore, MD: Williams & Wilkins Ca; 1987:318-332
9. Weill FS, Bihr E, Rohmer P, Zeltner F. Renal Sonography.
ed 2. Berlin, West Germany: Springer-Verlag Co;
1987:39-57
10. Chopra A, Teele RL Hydronephrosia in children: narrowing the differential diagnosis with ultrasound. J Clin
Ultra-sound. 1980;8:473-478
11. Aaronson IA, Cremin BJ. Clinical Pediatric Uroradiology. Edinburgh, Scotland Churchill Livingstone Co; 1984:62-64 12. Glassberg KI, Filmer RB. Renal dysplasia, hypoplasia, and
cystic disease of the kidney. In: Kelalis PP, King LR, Belman AB, ads. Clinical Pediatric Urology. ad 2, Philadel-phia, PA: WB Saunders Co; 1985:922-971
13. Bartholomew TH, Slovis TL, Kroovand RL, et al. The sonographic evaluation and management of simple renal cysts in children. J UroL 1980124:732-736
14. Stuck KJ, Koff SA, Siver TM. Ultrasonic features of mu!-ticystic dysplastic kldney. expanded diagnostic criteria.
Ra-diology. 1982;143:217-221
15. Pedicelli G, Jequier 5, Bowen A, et al. Multicystic dysplastic kidney: spontaneous regression demonstrated with
ultra-sound. Radiology. 1986;160:23-26
16. Sedman A, Bell P, Johnson MM, et aL Autosomal dominant polycystic kidney disease in childhoo& a longitudinal study. Kidney Int. 1987;31:1000-1005
17. Porche P, Noe HN, Stapleton FB. Unilateral presentation
of adult polycystic kidney disease in children. J UroL 1986;135:744-746
From The Wall Street Journal. Jan 20, 1989. 19. N’Guessan G, Stephens FD. Congenital superior ectopic
(thoracic) kidney. Urology. 1984;24:219-228
20. Dretler SP, Olsson CA, Pfister RC. The anatomic, radiologic
and clinical characteristics ofthe pelvic kidney: an analysis of 86 cases. J UroL 1971;105:623-627
21. Boatman DL, Culp DA, Juip Da, et al. Crossed renal ectopi&
J UroL 1972;108:30-31
22. Hendren WH, Donahoe PK, Pfister RC. Crossed renal
ec-topia in children. Urology. 1976;7:135-144
23. Hayden CK, Swiachuk LE Pediatric Ultrasonography. Bal-timore, MD: Williams & Wilkins Co; 1987:273-276
24. Glazel GP, Calabro A, Aragona F, et aL Blind ureterocele.
Eur UroL 1986;12:331-333
25. Currarino 0. Single vaginal ectopic ureter and Gartner’s duct cyst with ipsilateral renal hypoplasia and dysplasia (or
agenesis). J UroL 1982;128:988-993
26. Gordon RL, Pollack HM, Popky GL, et al. Simple serous cysts of the kidney in children. Radiology. 1979;131:357-361 27. Siegel MJ, Maclater WH. Simple cysts of the kidneys in
children. J UroL 1979;123:75-78
28. Ravden MI, Zuckerman HL, Kay CJ, et a!. Evaluation of solitary simple renal cysts in children. J UroL 1980;124:904-906
29. Pitte WR, Muecke EC. Horseshoe kidneys: a 40 years ex-perience. J UroL 1975;113:743-746
30. Weil FS, Bihr E, Rohmer P, et al. Renal Sonography. ed 2. Berlin, West Germany: Springer-Verlag Co; 1987:12 31. Mascatello VJ, Smith EH, Carrera CF, et al. Ultrasonic
evaluation of the obstructed duplex kidney. AJR. 1977;129:113-120
32. Rose JS, McCarthy J, Yeh H-C. Ultrasound diagnosis of ectopic ureterocele. Pediatr RadiOL 1979;8:17-20
33. Sumner TE, Crowe JE, Resnick MI. Diagnosis of ectopic ureterocele using ultrasound. Urology. 1980;15:82-85 34. Athey PA, Carpenter RI, Hadlock FP, Hedrick TD.
Ultra-sonic demonstration of ectopic ureterocele. Pediatrics. 1983;71:568-571
35. Geringer AM, Berdon WE, Seldin DW, et al. The diagnostic
approach to ectopic ureterocele and the renal duplication complex. J UroL 1983;129:539-542
36. Nussbaum AR, Dorst JP, Jeffs RD, et a!. Ectopic ureter and ureterocele: their varied sonographic manifestations. Ra-diology. 1986;159:227-235
37. Kelalls PP. Partial ureteral duplication. In: Kelalis PP, King LA, Belman AB, eds. Clinical Pediatric Urology. ad 2. Phil-adelphia, PA: WE Saunders Co; 1985:674-677
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