1571
Ultrasound
screening of newborn urinary tract
A non-invasive method to screen newborn babies for ureteric reflux might allow the possibility of appropriate action to prevent reflux nephropathy. We have tested the sensitivity of ultrasound screening of the urinary tract. 1061 unselected newborn infants born during 1986 were examined by ultrasound and the findings were recorded on videotape. Babies with dilated renal collecting systems underwent further
investigations (micturating cystourethrography, intravenous urography, or radioisotope study). With these methods, 11 children were found to have renal disorders. A postal follow-up survey was carried out when the children were 3 years old. 657 (62%) families responded. We searched for non-responders among children born in 1986 who had subsequently had a renal radioisotope investigation: 5 nonresponders were found among these children. Of the total, 24 children had had a urinary-tract infection: 3 more children with ureteric reflux were found; their neonatal ultrasound scans had suggested no abnormality. Thus, more than half the children of this cohort in whom hydronephrosis or ureteric reflux developed had only slight dilatation (less than 5 mm) on the neonatal scan. On review of the original videotapes there was no difference in internal dimension between left and right kidneys: the internal dimension was 5 mm or less in both kidneys in 96·3% of babies and 4 mm or less in 93·3%. Routine renal ultrasound scanning of newborn babies is of no value in detecting those who may have ureteric reflux: the number of other renal abnormalities likely to be detected is small.
Introduction Ureteric reflux in children has serious long-term implications for renal health and growth.! However, the disorder is not recognised in most cases until episodes of urinary infection occur; by this time, the renal parenchyma may already be damaged. A diagnosis of reflux in the newborn infant initiated by a non-invasive technique might enable appropriate action to be taken that could prevent reflux-related renal disease. To test this hypothesis, we undertook a screening project for newborn infants born at one
hospital during
1986.
Subjects and methods A senior radiographer (E. W. H.) scanned 1061 babies (38-4% of livebirths at Princess Mary Maternity Hospital, Newcastle upon Tyne, during 1986) between 48 h and 72 h after birth by the ultrasound technique previously described.2 Babies who had to be admitted to the special-care unit were not scanned unless the stay in the unit was short and they were returned to the postnatal ward: apart from this exclusion, the babies were unselected. 560 were male
and 501 female; the mean birthweight was 3290 g (SD 505; range 1105-4995 g), the mean head circumference 34-7 cm (1-3; 274-392 cm), and mean gestational age 39 weeks (1 6; 32-43 weeks). We asked each mother’s permission to examine her baby; we explained to her, verbally and in writing, the purpose of the survey, how it would be carried out, and what would be done if anything abnormal was found. The Newcastle Health Authority ethics committee approved the project. The findings in every baby were recorded on videotape and permanent images (hard copy) were made of each kidney at the end of the examination. The hard copies were reviewed a few days later (R. E. J. L. and J. E. S. S.) and the size of each renal pelvis was assessed on a scale of dilatation-none, minimum, moderate, or maximum. This judgment was inevitably subjective. Any anomalies in the urinary tract were noted. The assessors then decided whether to recommend a secondary investigation such as
rescanning,
micturating
cystourethrography
(MCUG),
intravenous urography, or a radioisotope study. When the children were 3 years old, we wrote to each mother requesting information about the child’s health to find out whether renal disease had occurred, enclosing a reply card with prepaid envelope. The mother was asked to say whether she thought any illness in the child had been related to the urinary tract. She was also asked to give the name and address of the family doctor, from whom we sought information about the nature of the illness and whether the child had been referred to another hospital; if so, relevant information was obtained from the consultant. A few children were already under the care of a paediatric nephrologist or urologist. During the follow-up survey the videotapes of each scan were reviewed (R. E. J. L.) so that the size of the renal collecting systems could be measured objectively: this task was done without reference to the hard copy or to the record of renal pelvic dilatation made soon after the first examination. The videotapes of 11 babies were unsuitable for examination, and 2 babies each had only one kidney. The internal dimension of each kidney was measured by replaying the original videorecording (’U-matic’) through the ultrasound scanner. The image showing the greatest anteroposterior dimension of the pelvicalyceal system was frozen and, by means of the caliper facility on the machine, the distance from the posterior wall of the system in a perpendicular across to the anterior wall was measured to the nearest 1 mm in both longitudinal and transverse sections. Only the central parts of the pelvicalyceal systems were measured, not the calyces. Because the measurements were made retrospectively, we could not ensure complete standardisation of the scan planes, but good longitudinal and transverse scans were available. It was simple to ensure that measurements were obtained from correctly orientated sections because the whole of each study had been recorded in real time. These observations allowed upper centiles of pelvic size to be determined from the distribution of the measurements. Furthermore, the relation between pelvic size and renal disease could be investigated.
Secondary investigations 33
(3-1%) babies had a second ultrasound scan (table i). The for rescanning were unusually bright renal pyramids on the
reasons
ADDRESSES: Department of Surgery (J. E. S. Scott, FRCS) and Division of Medical Statistics (J N S. Matthews, PhD), Medical School, University of Newcastle upon Tyne; and Department of Radiology (R E J. Lee, FRCR, E. W. Hunter, DCR[D]), and Child Health (M G. Coulthard, FRCP), Royal Victoria Infirmary, Newcastle upon Tyne, UK. Correspondence to Dr R E J. Lee, Department of Radiology, Royal Victoria Infirmary, Newcastle upon Tyne NE1 4LP, UK.
1572
TABLE I-SECONDARY INVESTIGATIONS BY TIME OF YEAR
TABLE II-SECONDARY INVESTIGATIONS AND FINDINGS BY INTERNAL DIMENSION OF BIGGER KIDNEY
original scan in 13; suspected solitary kidney in 2 and duplex kidney in 1; adrenal haemorrhage in 1;and substantial (moderate or maximum) dilatation of at least one renal pelvis in 16. MCUG was done in 51 (4-9%) babies (table 1). 1 baby had a suspected duplex kidney; 1 unusually bright renal pyramids; 1 a cystic lesion in the abdominal pelvis; and the remainder substantial renal pelvic dilatation. Intravenous urography was done in 2 babies who had renal dilatation in the absence of ureteric reflux. Technetium-99m dimercaptosuccinic acid renal scans were carried out in 3 babies; in 1 because ureteric reflux had been found and in 2 to confirm that a kidney was absent (1 of the latter had a horseshoe-shaped kidney).
Results The renal internal dimensions are shown as a bivariate The largest dimension measured was 13 mm: 15 babies had at least one measurement exceeding 7 mm. The hypothesis of symmetry for these data (ie, a symmetrical distribution of dimensions between sides) was decisively rejected when tested by the statistic described by Plackett;3 p was less than 0-001 with (because of the sparsity of the data) a randomisation distribution rather than the usual chi-squared approximation. This result was due mainly to a predominance of left kidneys with 1-2 mm dilatation when right kidneys had none. A possible explanation is that the liver compresses the right kidney and prevents expansion of the collecting system. We have previously reportedadifference between right and left kidneys in external dimension. The larger kidney had an internal dimension of 5 mm or less in 96-3% of babies and
histogram (figure).
Bivariate scan.
histogram of renal pelvis size
on
neonatal ultrasound
*Of babies m the dimension group IVU Intravenous urogram
tPlus 1 baby whose kidneys were not measured
=
4 mm or less in 93-3%. A reference range of 0-5 mm would therefore include about 95 % of the population. Bright renal pyramids were characterised by increased echogenicity of the normally echolucent medullary pyramids. When babies were rescanned at 2-3 weeks of age, all had normal echolucent pyramids. In view of this normal appearance and the absence of any clinical abnormality, no further follow-up was carried out. No serious renal disease has subsequently developed in these children. Because dilatation of either kidney prompts investigation, the findings were related to the bigger dimension in each baby (table 11). 3 (0-3%) babies had ureteric reflux, unilateral in 2, bilateral in 1. 5 babies had hydronephrosis, 3 unilateral and 2 bilateral (1of these had bilateral ureteric reflux). The other renal disorders were unilateral cystic kidney in 1 baby, duplex kidney in 1, horseshoe kidney in 1, and small adrenal haemorrhage in 1. 657 (62%) of families responded to the 3-year follow-up survey. Urinary-tract infections were reported and confirmed by the family doctor in 21 (3-2%) children. 31 (4-7%) had had a non-urinary-related illness. 3 more children with ureteric reflux were found. In 1 of these bilateral hydronephrosis was suspected at birth but investigations, including MCUG, did not reveal reflux. In the 2 other babies the collecting systems were too small to be measurable on the original scans, a judgment that was confirmed when they and the videotapes were rescrutinised. Other findings on follow-up included 1 child with intussusception, 1 death which was sudden and unexplained, and 1 child with renal calculi. Because 38% of families did not respond to the postal inquiry, some children in whom serious renal disease developed may not have been discovered. We tried to trace non-responders through the medical physics departments of the major regional hospitals: we searched for nonresponders on a list of all children born in 1986 who had a renal radioisotope investigation before Dec 31, 1989. Children who had a radioisotope investigation between Dec 31, 1989, and June 30, 1991, were also listed: although these investigations were done outside the time-frame of the follow-up survey, it was possible that the initial urinary symptoms might have developed within the survey time. 5 non-responders were found among these 342 children; 3 had had urinary-tract infections but none had detectable renal disorders.
1573
Discussion Steinhart and colleagues4 found by ultrasound screening "significant uropathology" in 6 of 437 (1-4%) apparently healthy unselected infants aged between 2 and 10 months. 6 other infants had minor abnormalities. In our series ureteric reflux was diagnosed in 6 children (0-6%) but the disorder was suspected at the initial postnatal scan in only 3 of these; reflux came to light during the 3-year follow-up in the rest. In 2 the renal collecting system was too small to be measurable on the neonatal scan and 1 apparently did not have reflux at that time. Thus, the early neonatal reflux diagnosis rate was only 03%. Only 3 (0-3%) babies were found on neonatal screening to have non-refluxing
hydronephrosis; none required surgery. The discrepancy between the studies may be accounted for by selection bias. The American study was carried out in a private practice; only 25% of mothers offered an ultrasound examination for their babies agreed to participate. Perhaps these mothers chose to take part because their babies had occasionally been unwell even though the mothers did not report illness. Brightly echogenic renal pyramids are known to be associated with disorders such as nephrocalcinosis and medullary cystic disease.5.6 However, the ultrasonographic abnormalities persist in these disorders, whereas in our subjects they disappeared in less than 2 weeks. It is possible that this feature was due to early neonatal dehydration, which causes transient deposition of protein in the renal collecting tubules-a self-limiting disorder with no apparent longterm sequelae. Because very few urological abnormalities were discovered during the first 3 months of our study substantially fewer babies were subjected to the secondary investigations in subsequent months (table I). We originally intended that babies born during 1986 at the same maternity hospital who were not scanned would form a control group. Since the number of urological abnormalities discovered by the screening trial was so small, there seemed little point in attempting to trace these potential controls. Since the informal assessment of pelvic dilatation was one of the factors on which a recommendation of secondary investigations was based, detection of renal disease may have been biased towards babies with greater dilatation. However, it is more likely that all children in the series with ureteric reflux or hydronephrosis still living locally have been found by the postal survey or the search of the medical physics departments’ records. Such bias would amplify the apparent sensitivity of ultrasound screening. However, more than half the children with hydronephrosis or ureteric reflux had only slight dilatation (5 mm or less). Although only 11 cases were found, a larger study is not justified because ultrasound scanning is unlikely to be sufficiently sensitive for routine use. A Lancet editorial has suggested that ureteric reflux might be detectable by antenatal or early postnatal ultrasound scanning. Fetal ureteric reflux does occur and can be anticipated by antenatal scanning,8-1O but most of the affected fetuses are male and have massive reflux, and many of their kidneys have evidence of damage at birth. They form a reflux population different from that we tried to muster-namely, children (mostly girls) with modest reflux but serious renal damage by the time the reflux is diagnosed. Marshall et alil suggested that reflux could be anticipated by colour doppler imaging. However, they studied a small
number of cases with a wide age range (26 days to 9 years); although they found a significant difference in the distance of the ureteric orifice from the midline between children with and without reflux, there was substantial overlap between the groups, so the method is unlikely to be reliable in individual cases or in very young infants. To determine whether the method has sufficient sensitivity and specificity to predict reflux, it will be necessary to study a large cohort of healthy infants. We thank Newcastle Health Authority Research Committee for financial support; the doctors and nurses of the departments of child health and obstetrics, Princess Mary Maternity Hospital, Newcastle upon Tyne, for their cooperation; and Dr D. P. Surtees of the Computing Service Department, University of Newcastle upon Tyne, for help with the figure. The table from which the figure was derived is available from Dr J. N. S. Matthews.
REFERENCES 1. Hodson CJ, Edwards D. Chronic pyelonephritis and vesico-ureteric reflux. Clin Radiol 1960; 11: 219-31. 2. Scott JES, Hunter EW, Lee REJ, Matthews JNS. Ultrasound measurement of renal size in newborn infants. Arch Dis Child 1990; 65: 361-64. 3. Plackett RL. The analysis of categorical data, 2nd ed. London: Griffin, 1981: 79. 4. Steinhart JM, Kuhn JP, Eisenberg B, Vaughan RL, Maggioli AG, Cozza TF. Ultrasound screening of healthy infants for urinary tract abnormalities. Pediatrics 1988; 82: 609-14. 5. Diard F, Nicolau A, Bernard S. Intrarenal reflux: a new cause of medullary hyperechogenicity? Pediatr Radiol 1987; 17: 154-55. 6. Falkoff GE, Rigsby CM, Rosenfield AT. Partial, combined cortical and medullary nephrocalcinosis: US and CT patterns in AIDS associated with MAI infection. Radiology 1987; 162: 343-44. 7. Editorial. Prevention of reflux nephropathy. Lancet 1991; 338: 1050. 8. Scott JES. Fetal ureteric reflux. Br J Urol 1987; 59: 291-96. 9. Gordon AC, Thomas DFM, Arthur RJ, Irving HC, Smith SEW. Prenatally diagnosed reflux: a follow-up study. Br J Urol 1990; 65: 407-12. 10. Anderson PAM, Rickwood AMK. Features of primary vesicoureteric reflux detected by prenatal sonography. Br J Urol 1991; 67: 267-71. 11. Marshall JL, Johnson ND, De Campo MP. Vesicoureteric reflux in children: prediction with color doppler imaging. Radiology 1990; 175: 355-58.
From The Lancet Summer
days
With the advent of genuine summer weather the question of holidays becomes a practical one. The increasing tendency of late years among a large and influential section of the community to postpone the holiday season to the end of summer and the beginning of autumn finds its explanation, probably, rather in social reasons than in any natural fitness of things. September is an excellent month for those who prefer continental travel, and October and November are often very charming on our southern coast, but July and August are the real crown of summer, and must remain for large classes, and especially the young, the natural period for rest, recreation, and change. It is then that sea bathing can be best enjoyed, that yachting presents its maximum of pleasure, and that mountaineering can be pursued with least apprehension of fog. The long day permits the prosecution of outdoor occupation to a late hour, and saves the holiday-maker from the ennui which is apt to overtake him in the autumnal evening spent in hotel, pension, or lodging-house....The immense extension of the summer holiday is a comparatively modem habit, but the practice had its type in ancient times. The Roman noble delighted to remove from the heat and bustle of Rome to Baiae or Salemum. Horace used to spend the dog-days in the comparative cool of his upland Sabine farm. Tiberius made of Capreae a resort unhappily too notorious. But travel for the multitude is a modem idea, and would have seemed impossible and absurd in ancient times.
(June 20, 1891)
Ultrasound
screening of newborn urinary tract
A non-invasive method to screen newborn babies for ureteric reflux might allow the possibility of appropriate action to prevent reflux nephropathy. We have tested the sensitivity of ultrasound screening of the urinary tract. 1061 unselected newborn infants born during 1986 were examined by ultrasound and the findings were recorded on videotape. Babies with dilated renal collecting systems underwent further
investigations (micturating cystourethrography, intravenous urography, or radioisotope study). With these methods, 11 children were found to have renal disorders. A postal follow-up survey was carried out when the children were 3 years old. 657 (62%) families responded. We searched for non-responders among children born in 1986 who had subsequently had a renal radioisotope investigation: 5 nonresponders were found among these children. Of the total, 24 children had had a urinary-tract infection: 3 more children with ureteric reflux were found; their neonatal ultrasound scans had suggested no abnormality. Thus, more than half the children of this cohort in whom hydronephrosis or ureteric reflux developed had only slight dilatation (less than 5 mm) on the neonatal scan. On review of the original videotapes there was no difference in internal dimension between left and right kidneys: the internal dimension was 5 mm or less in both kidneys in 96·3% of babies and 4 mm or less in 93·3%. Routine renal ultrasound scanning of newborn babies is of no value in detecting those who may have ureteric reflux: the number of other renal abnormalities likely to be detected is small.
Introduction Ureteric reflux in children has serious long-term implications for renal health and growth.! However, the disorder is not recognised in most cases until episodes of urinary infection occur; by this time, the renal parenchyma may already be damaged. A diagnosis of reflux in the newborn infant initiated by a non-invasive technique might enable appropriate action to be taken that could prevent reflux-related renal disease. To test this hypothesis, we undertook a screening project for newborn infants born at one
hospital during
1986.
Subjects and methods A senior radiographer (E. W. H.) scanned 1061 babies (38-4% of livebirths at Princess Mary Maternity Hospital, Newcastle upon Tyne, during 1986) between 48 h and 72 h after birth by the ultrasound technique previously described.2 Babies who had to be admitted to the special-care unit were not scanned unless the stay in the unit was short and they were returned to the postnatal ward: apart from this exclusion, the babies were unselected. 560 were male
and 501 female; the mean birthweight was 3290 g (SD 505; range 1105-4995 g), the mean head circumference 34-7 cm (1-3; 274-392 cm), and mean gestational age 39 weeks (1 6; 32-43 weeks). We asked each mother’s permission to examine her baby; we explained to her, verbally and in writing, the purpose of the survey, how it would be carried out, and what would be done if anything abnormal was found. The Newcastle Health Authority ethics committee approved the project. The findings in every baby were recorded on videotape and permanent images (hard copy) were made of each kidney at the end of the examination. The hard copies were reviewed a few days later (R. E. J. L. and J. E. S. S.) and the size of each renal pelvis was assessed on a scale of dilatation-none, minimum, moderate, or maximum. This judgment was inevitably subjective. Any anomalies in the urinary tract were noted. The assessors then decided whether to recommend a secondary investigation such as
rescanning,
micturating
cystourethrography
(MCUG),
intravenous urography, or a radioisotope study. When the children were 3 years old, we wrote to each mother requesting information about the child’s health to find out whether renal disease had occurred, enclosing a reply card with prepaid envelope. The mother was asked to say whether she thought any illness in the child had been related to the urinary tract. She was also asked to give the name and address of the family doctor, from whom we sought information about the nature of the illness and whether the child had been referred to another hospital; if so, relevant information was obtained from the consultant. A few children were already under the care of a paediatric nephrologist or urologist. During the follow-up survey the videotapes of each scan were reviewed (R. E. J. L.) so that the size of the renal collecting systems could be measured objectively: this task was done without reference to the hard copy or to the record of renal pelvic dilatation made soon after the first examination. The videotapes of 11 babies were unsuitable for examination, and 2 babies each had only one kidney. The internal dimension of each kidney was measured by replaying the original videorecording (’U-matic’) through the ultrasound scanner. The image showing the greatest anteroposterior dimension of the pelvicalyceal system was frozen and, by means of the caliper facility on the machine, the distance from the posterior wall of the system in a perpendicular across to the anterior wall was measured to the nearest 1 mm in both longitudinal and transverse sections. Only the central parts of the pelvicalyceal systems were measured, not the calyces. Because the measurements were made retrospectively, we could not ensure complete standardisation of the scan planes, but good longitudinal and transverse scans were available. It was simple to ensure that measurements were obtained from correctly orientated sections because the whole of each study had been recorded in real time. These observations allowed upper centiles of pelvic size to be determined from the distribution of the measurements. Furthermore, the relation between pelvic size and renal disease could be investigated.
Secondary investigations 33
(3-1%) babies had a second ultrasound scan (table i). The for rescanning were unusually bright renal pyramids on the
reasons
ADDRESSES: Department of Surgery (J. E. S. Scott, FRCS) and Division of Medical Statistics (J N S. Matthews, PhD), Medical School, University of Newcastle upon Tyne; and Department of Radiology (R E J. Lee, FRCR, E. W. Hunter, DCR[D]), and Child Health (M G. Coulthard, FRCP), Royal Victoria Infirmary, Newcastle upon Tyne, UK. Correspondence to Dr R E J. Lee, Department of Radiology, Royal Victoria Infirmary, Newcastle upon Tyne NE1 4LP, UK.
1572
TABLE I-SECONDARY INVESTIGATIONS BY TIME OF YEAR
TABLE II-SECONDARY INVESTIGATIONS AND FINDINGS BY INTERNAL DIMENSION OF BIGGER KIDNEY
original scan in 13; suspected solitary kidney in 2 and duplex kidney in 1; adrenal haemorrhage in 1;and substantial (moderate or maximum) dilatation of at least one renal pelvis in 16. MCUG was done in 51 (4-9%) babies (table 1). 1 baby had a suspected duplex kidney; 1 unusually bright renal pyramids; 1 a cystic lesion in the abdominal pelvis; and the remainder substantial renal pelvic dilatation. Intravenous urography was done in 2 babies who had renal dilatation in the absence of ureteric reflux. Technetium-99m dimercaptosuccinic acid renal scans were carried out in 3 babies; in 1 because ureteric reflux had been found and in 2 to confirm that a kidney was absent (1 of the latter had a horseshoe-shaped kidney).
Results The renal internal dimensions are shown as a bivariate The largest dimension measured was 13 mm: 15 babies had at least one measurement exceeding 7 mm. The hypothesis of symmetry for these data (ie, a symmetrical distribution of dimensions between sides) was decisively rejected when tested by the statistic described by Plackett;3 p was less than 0-001 with (because of the sparsity of the data) a randomisation distribution rather than the usual chi-squared approximation. This result was due mainly to a predominance of left kidneys with 1-2 mm dilatation when right kidneys had none. A possible explanation is that the liver compresses the right kidney and prevents expansion of the collecting system. We have previously reportedadifference between right and left kidneys in external dimension. The larger kidney had an internal dimension of 5 mm or less in 96-3% of babies and
histogram (figure).
Bivariate scan.
histogram of renal pelvis size
on
neonatal ultrasound
*Of babies m the dimension group IVU Intravenous urogram
tPlus 1 baby whose kidneys were not measured
=
4 mm or less in 93-3%. A reference range of 0-5 mm would therefore include about 95 % of the population. Bright renal pyramids were characterised by increased echogenicity of the normally echolucent medullary pyramids. When babies were rescanned at 2-3 weeks of age, all had normal echolucent pyramids. In view of this normal appearance and the absence of any clinical abnormality, no further follow-up was carried out. No serious renal disease has subsequently developed in these children. Because dilatation of either kidney prompts investigation, the findings were related to the bigger dimension in each baby (table 11). 3 (0-3%) babies had ureteric reflux, unilateral in 2, bilateral in 1. 5 babies had hydronephrosis, 3 unilateral and 2 bilateral (1of these had bilateral ureteric reflux). The other renal disorders were unilateral cystic kidney in 1 baby, duplex kidney in 1, horseshoe kidney in 1, and small adrenal haemorrhage in 1. 657 (62%) of families responded to the 3-year follow-up survey. Urinary-tract infections were reported and confirmed by the family doctor in 21 (3-2%) children. 31 (4-7%) had had a non-urinary-related illness. 3 more children with ureteric reflux were found. In 1 of these bilateral hydronephrosis was suspected at birth but investigations, including MCUG, did not reveal reflux. In the 2 other babies the collecting systems were too small to be measurable on the original scans, a judgment that was confirmed when they and the videotapes were rescrutinised. Other findings on follow-up included 1 child with intussusception, 1 death which was sudden and unexplained, and 1 child with renal calculi. Because 38% of families did not respond to the postal inquiry, some children in whom serious renal disease developed may not have been discovered. We tried to trace non-responders through the medical physics departments of the major regional hospitals: we searched for nonresponders on a list of all children born in 1986 who had a renal radioisotope investigation before Dec 31, 1989. Children who had a radioisotope investigation between Dec 31, 1989, and June 30, 1991, were also listed: although these investigations were done outside the time-frame of the follow-up survey, it was possible that the initial urinary symptoms might have developed within the survey time. 5 non-responders were found among these 342 children; 3 had had urinary-tract infections but none had detectable renal disorders.
1573
Discussion Steinhart and colleagues4 found by ultrasound screening "significant uropathology" in 6 of 437 (1-4%) apparently healthy unselected infants aged between 2 and 10 months. 6 other infants had minor abnormalities. In our series ureteric reflux was diagnosed in 6 children (0-6%) but the disorder was suspected at the initial postnatal scan in only 3 of these; reflux came to light during the 3-year follow-up in the rest. In 2 the renal collecting system was too small to be measurable on the neonatal scan and 1 apparently did not have reflux at that time. Thus, the early neonatal reflux diagnosis rate was only 03%. Only 3 (0-3%) babies were found on neonatal screening to have non-refluxing
hydronephrosis; none required surgery. The discrepancy between the studies may be accounted for by selection bias. The American study was carried out in a private practice; only 25% of mothers offered an ultrasound examination for their babies agreed to participate. Perhaps these mothers chose to take part because their babies had occasionally been unwell even though the mothers did not report illness. Brightly echogenic renal pyramids are known to be associated with disorders such as nephrocalcinosis and medullary cystic disease.5.6 However, the ultrasonographic abnormalities persist in these disorders, whereas in our subjects they disappeared in less than 2 weeks. It is possible that this feature was due to early neonatal dehydration, which causes transient deposition of protein in the renal collecting tubules-a self-limiting disorder with no apparent longterm sequelae. Because very few urological abnormalities were discovered during the first 3 months of our study substantially fewer babies were subjected to the secondary investigations in subsequent months (table I). We originally intended that babies born during 1986 at the same maternity hospital who were not scanned would form a control group. Since the number of urological abnormalities discovered by the screening trial was so small, there seemed little point in attempting to trace these potential controls. Since the informal assessment of pelvic dilatation was one of the factors on which a recommendation of secondary investigations was based, detection of renal disease may have been biased towards babies with greater dilatation. However, it is more likely that all children in the series with ureteric reflux or hydronephrosis still living locally have been found by the postal survey or the search of the medical physics departments’ records. Such bias would amplify the apparent sensitivity of ultrasound screening. However, more than half the children with hydronephrosis or ureteric reflux had only slight dilatation (5 mm or less). Although only 11 cases were found, a larger study is not justified because ultrasound scanning is unlikely to be sufficiently sensitive for routine use. A Lancet editorial has suggested that ureteric reflux might be detectable by antenatal or early postnatal ultrasound scanning. Fetal ureteric reflux does occur and can be anticipated by antenatal scanning,8-1O but most of the affected fetuses are male and have massive reflux, and many of their kidneys have evidence of damage at birth. They form a reflux population different from that we tried to muster-namely, children (mostly girls) with modest reflux but serious renal damage by the time the reflux is diagnosed. Marshall et alil suggested that reflux could be anticipated by colour doppler imaging. However, they studied a small
number of cases with a wide age range (26 days to 9 years); although they found a significant difference in the distance of the ureteric orifice from the midline between children with and without reflux, there was substantial overlap between the groups, so the method is unlikely to be reliable in individual cases or in very young infants. To determine whether the method has sufficient sensitivity and specificity to predict reflux, it will be necessary to study a large cohort of healthy infants. We thank Newcastle Health Authority Research Committee for financial support; the doctors and nurses of the departments of child health and obstetrics, Princess Mary Maternity Hospital, Newcastle upon Tyne, for their cooperation; and Dr D. P. Surtees of the Computing Service Department, University of Newcastle upon Tyne, for help with the figure. The table from which the figure was derived is available from Dr J. N. S. Matthews.
REFERENCES 1. Hodson CJ, Edwards D. Chronic pyelonephritis and vesico-ureteric reflux. Clin Radiol 1960; 11: 219-31. 2. Scott JES, Hunter EW, Lee REJ, Matthews JNS. Ultrasound measurement of renal size in newborn infants. Arch Dis Child 1990; 65: 361-64. 3. Plackett RL. The analysis of categorical data, 2nd ed. London: Griffin, 1981: 79. 4. Steinhart JM, Kuhn JP, Eisenberg B, Vaughan RL, Maggioli AG, Cozza TF. Ultrasound screening of healthy infants for urinary tract abnormalities. Pediatrics 1988; 82: 609-14. 5. Diard F, Nicolau A, Bernard S. Intrarenal reflux: a new cause of medullary hyperechogenicity? Pediatr Radiol 1987; 17: 154-55. 6. Falkoff GE, Rigsby CM, Rosenfield AT. Partial, combined cortical and medullary nephrocalcinosis: US and CT patterns in AIDS associated with MAI infection. Radiology 1987; 162: 343-44. 7. Editorial. Prevention of reflux nephropathy. Lancet 1991; 338: 1050. 8. Scott JES. Fetal ureteric reflux. Br J Urol 1987; 59: 291-96. 9. Gordon AC, Thomas DFM, Arthur RJ, Irving HC, Smith SEW. Prenatally diagnosed reflux: a follow-up study. Br J Urol 1990; 65: 407-12. 10. Anderson PAM, Rickwood AMK. Features of primary vesicoureteric reflux detected by prenatal sonography. Br J Urol 1991; 67: 267-71. 11. Marshall JL, Johnson ND, De Campo MP. Vesicoureteric reflux in children: prediction with color doppler imaging. Radiology 1990; 175: 355-58.
From The Lancet Summer
days
With the advent of genuine summer weather the question of holidays becomes a practical one. The increasing tendency of late years among a large and influential section of the community to postpone the holiday season to the end of summer and the beginning of autumn finds its explanation, probably, rather in social reasons than in any natural fitness of things. September is an excellent month for those who prefer continental travel, and October and November are often very charming on our southern coast, but July and August are the real crown of summer, and must remain for large classes, and especially the young, the natural period for rest, recreation, and change. It is then that sea bathing can be best enjoyed, that yachting presents its maximum of pleasure, and that mountaineering can be pursued with least apprehension of fog. The long day permits the prosecution of outdoor occupation to a late hour, and saves the holiday-maker from the ennui which is apt to overtake him in the autumnal evening spent in hotel, pension, or lodging-house....The immense extension of the summer holiday is a comparatively modem habit, but the practice had its type in ancient times. The Roman noble delighted to remove from the heat and bustle of Rome to Baiae or Salemum. Horace used to spend the dog-days in the comparative cool of his upland Sabine farm. Tiberius made of Capreae a resort unhappily too notorious. But travel for the multitude is a modem idea, and would have seemed impossible and absurd in ancient times.
(June 20, 1891)
