URINARY SCREENING IN CHILDREN 3-7 YEARS OLD

1369

(congenital megacolon), a condition in which there is a congenital absence of myenteric ganglia together with an increase in the number or size of neighbouring autonomic nerve fibres.8 Our series is too small to relate the severity of the exomphalos to

the results of the AChE, test, but if the mechanism

we

have

suggested for AChE being positive is correct, the AChE test is more likely to be positive if the lesion is large and the abdominal contents well exposed to amniotic fluid. Recently Buamah et al.9 tested the amniotic fluid from 4 pregnancies associated with exomphalos in the absence of NTD. Their test was similar to our own but since they did not use a specific AChE inhibitor their results indicated the presence of an enzyme hydrolysing acetylthiocholine which need not necessarily be AChE. All 4 affected pregnancies yielded positive results. As far as we are aware the 14 cases of exomphalos identified from women who were screened for open NTD represent all the births with this condition in the absence of NTD which occurred among the screened population in Oxford and Edinburgh from 1975 to 1979. 2 affected pregnancies ended in a miscarriage, leaving 12 cases, a prevalence of 0-252 per 1000 births. This may be an overestimate since 1 or 2 affected pregnancies which were terminated might otherwise have miscarried, but it is nonetheless virtually the same as the rate of 0.251 per 1000 obtained in Birmingham, England, between 1950 and 1969 which was based on 102 births with exomphalos in the absence of a NTD out of 406 291 total births (I.

Leck, personal communication). Our results indicate that serum or plasma AFP screening is likely to identify about three-quarters of all cases of exomphalos in the absence of NTD, although about a third will subsequently have a negative amniotic fluid AFP or a negative AChE test. Since NTDs are more common than exomphalos and a greater proportion can be detected antenatally, more pregnancies with positive amniotic fluid AFP and AChE tests will be associated with NTD than with exomphalos, the ratio in the U.K. being about 20:1. The desirability of making an antenatal diagnosis of exomphalos is uncertain. The condition covers a wide spectrum; mild cases which can readily be repaired surgically occur, although the proportion which fall in this category is not known. Until further information is available on the natural history of exomphalos it is impossible to judge how desirable it is to diagnose the abnormality in utero. ,

We thank Mr P. Foley for technical assistance, Nora Jones and Criena Fitzgerald for helping to collect information on the outcomes of preganncy, Dr C. Redman for arranging a computer search for all births associated with exomphalos in Oxford, Mr W. Scobie for reviewing the pxdiatric surgical records in Edinburgh, and Dr Jillian Boreham for computing assistance. We also thank the R. J. Harris Trusts for financial support. I.C.R.F. Cancer Epidemiology and Clinical Trials Unit, Radcliffe Infirmary, Oxford

N. J. WALD

University Department of Pharmacology, Oxford

A. D. SMITH

H. S. CUCKLE R. D. BARLOW

Nuffield Department of Obstetrics and Gynæcology,

John Radcliffe Hospital, Oxford

Department of Medical Genetics, University of Oxford University Department of Human Genetics, Western General Hospital, Edinburgh Department of Clinical Chemistry, Western General Hospital, Edinburgh

G. M. STIRRAT A. C. TURNBULL M. BOBROW

SIR,-More than 95% of Swedish children

up to 7 years of

regularly examined at child health care centres. The aim of this study was to evaluate the need for such children’s urine to be screened for bacteria, protein, glucose, and sediage

are

ment.

At the child health care centre in Vaxjo, a town with about 35 000 inhabitants, 4290 urine samples from 3824 unselected pre-school children were analysed. The samples from girls were collected over a 10-year period and those from the boys in a year. Age at sampling: 3 years 321 (8-4%), 4 years 2696 (70.5%), 5 years 470 (12.3%), 6 years 309 (8.1%), and 7 years 28 (0-7%). About 80% of the girls living in

the

area

have been

investigated.

Children with symptomatic urinary-tract infections were referred pxdiatricians for treatment and are not included in the study.

to

In the first 5 years the external genitalia were washed with 0.1% benzalkonium solution or sterile water before sampling. Later, midstream samples were collected at home without prior cleansing.

Cultures were done by a semiquantitative method.I Growth was said moderate (10’-105), or abundant (>105 be scanty (<104), bacteria/ ml urine). If growth was moderate or abundant, a new sample was analysed after 1-2 weeks. Significant bacteriuria was defined as two consecutive cultures giving growth of > 105 bacteria/ml. to

All samples were examined with ’Albustrix’ and ’Clinistix’ for protein and glucose. The sediment of centrifuged urine was examined microscopically (x400). More than 10 leucocytes per microscopic field was considered abnormal.

Significant bacteriuria was not found in any of the 344 boys. The initial samples from 72 of the 3480 girls (2-1%) gave abundant growth. Control culture gave abundant growth in 28 (0-8%) which indicates 1-3% false positive results from the first cultures. These false positive results may also reflect spontaneous healing. To assess the number of false negative tests, new samples from all cases with moderate growth were recultured. None gave abundant growth in two consecutive samples. The urine from all except 2 of the children with significant bacteriuria showed growth of coliform rods. 1 sample showed growth of proteus and 1 of enterococcus. Those samples with moderate or scanty growth often showed growth of enterococci and staphylococci as a sign of contamination. The contamination of midstream samples when compared, with washed samples did not influence the result of signifi-

cant growth. Among the girls

with bacteriuria only about 45% had an abnormal sediment. On the other hand many girls without bacteriuria had an abnormal sediment. About 20 apparently healthy children had transient proteinuria. None had permanent proteinuria nor glycosuria. The frequency of asymptomatic bacteriuria in 3-7-year old girls was 0-8%. Pyuria occurred in only about half of the cases of asymptomatic bacteriuria. These results are similar to those in a previous investigation in Sweden.2 In both series there is a predominance of 4-year-old girls because of the general examination at the child health care centres in Sweden at this age. In boys no bacteriuria was found, in accordance with earlier studies.3 This study shows that in pre-school age groups tests for proteinuria, glycosuria, and sediment are of no value. Urinary-tract infections may cause renal damage in children but asymptomatic bacteriuria has not yet been proved to cause such changes.4 The value of screening for asymptomatic bacteriuria is therefore questionable.5

Departments of Pædiatrics, Växjö Hospital, and University of Lund, General Hospital,

LENNART RIGHARD

S-214 01 Malmö, Sweden

D. J. H. BROCK S. M. STEIN

8. Dale G, Bonham JR, Lowdon P, Wagget J, Rangecroft L, Scott DJ. Diagnostic value of rectal mucosal acetylcholinesterase levels m Hirschsprung’s disease. Lancet 1979;i: 347-49. 9. Buamah RK, Evans C, Milford Ward A. Amniotic fluid acetylcholinesterase isoenzyme pattern in the diagnosis of neural-tube defects. Clin Chim Acta

1980; 103: 147-51.

URINARY SCREENING IN CHILDREN 3-7 YEARS OLD

1. O’Sullivan DJ, et al. J Clin Pathol 1960; 13: 527. 2. Köhler L, Fritz H, Scherstén B. Health control

of four-year-old children. A study of bacteriuria. Acta Pædiat Scand 1972; 61: 289. 3. Kunin CM, Deutscher R, Paquin AJ. Urinary tract infection in school children: an epidemiologic clinical and laboratory study. Medicine 1964; 43: 91. 4.

Lindberg U, Claesson J, Hansson LÅ, Jodal U. Asymptomatic bacteriuria in schoolgirls VIII. Clinical course during a 3-year follow-up. J Pediat 1978;

92: 194. 5. Editorial. Covert bacteriuria: Peril

or

partnership? Br Med J 1978;

i 1649.