Reliability of ultrasonography in identification of reflux nephropathy in children.

OBJECTIVE--To assess the ability of ultrasonography to identify reflux nephropathy in children after urinary tract infection. DESIGN--Ten experienced radiologists performed a total of 240 ultrasonographic examinations of kidneys in a one day study. The examiners were unaware of the results of previous radiological and clinical examinations and of the proportions of normal and abnormal kidneys. Urography was used as method of reference, supported by static renal scintigraphy (dimercaptosuccinic acid labelled with technetium-99m) in half of the cases. SETTING--Outpatient radiology department. SUBJECTS--25 children aged 2-16 years (20 kidneys with and 30 kidneys without renal scarring). MAIN OUTCOME MEASURES--Renal scarring. Overall size and length of kidneys. Sensitivity and specificity including receiver operator characteristics and variation between observers. RESULTS--With renal scarring as the diagnostic criterion and including cases classified as abnormal, probably abnormal, and uncertain the sensitivity of ultrasonography was 54% (specificity 80%). Addition of reduced renal size as a diagnostic criterion increased the sensitivity to 64% (specificity 79%). There were, however, wide variations between observers, with sensitivity ranging between 40% and 90% (specificity 94% to 65%). CONCLUSIONS--Because of its low sensitivity and specificity and poor agreement between observers, ultrasonography cannot be generally recommended for the detection of reflux nephropathy after urinary tract infection in children.     

Ultrasonography and abdominal radiography versus intravenous urography in investigation of urinary tract infection in men: prospective incident cohort study

ObjectivesTo compare ultrasonography and abdominal radiography with intravenous urography in the investigation of urinary tract infection in men.DesignProspective study in two hospital departments. Radiological procedures and urological assessments performed on different days by different cliniciansSettingDistrict general hospital.ParticipantsConsecutive series of men (n=114) referred to the department of urology for investigation of proved urinary tract infection.InterventionsUltrasonography and intravenous urography of renal tract and assessment of urinary flow rate. Clinical assessment, cystoscopy, urodynamic studies, and transrectal ultrasonography with biopsy.ResultsImportant abnormalities were seen in 53 of 100 fully evaluated patients, the most common being a poorly emptying bladder (34). The combination of plain radiographs of kidneys, ureter, and bladder and ultrasonography detected more abnormalities than intravenous urography alone. No important abnormality was missed by this combination (sensitivity 100% and specificity 93%).ConclusionsUltrasonography with abdominal radiography is as accurate as intravenous urography in detecting important urological abnormalities in men presenting with urinary tract infection. This combination is safer than intravenous urography and should be the initial investigation for such patients. Additional determination of urinary flow rate is useful for the assessment of an incompletely emptying bladder.

What is already known on this topic

Ultrasonography alone is the primary investigation of choice for urinary tract infection in children and womenUltrasonography has limited sensitivity for renal stones and poor sensitivity for ureteric stonesUrinary infection is less common in men than women and the risk factors are different

What this study adds

Ultrasonography is as effective as intravenous urography in men with urinary tract infection only when it is combined with plain radiographyIn men aged over 50 an incompletely emptying bladder is the most common abnormalityIn such patients determination of urinary flow rate is particularly helpful     

Ultrasonography compared with intravenous urography in investigation of urinary tract infection in adults.

OBJECTIVE--To compare ultrasonography with intravenous urography for investigating adults with proved urinary tract infection. DESIGN--Prospective study of patients presenting consecutively for radiological investigation of urinary tract infection between October 1988 and December 1989. Both investigations were performed concurrently and performed independently on routine lists by different duty radiologists, each of whom knew the details on the request form but not the findings of the other investigation. SETTING--Radiology department of a teaching hospital. PATIENTS--158 Consecutive adults (89 women, 69 men; mean age 49.7 (range 18-83)) referred from general practitioners and hospital outpatient clinics with a history of proved urinary tract infection. INTERVENTIONS--Urography and ultrasonography performed concurrently. When both examinations gave normal findings no clinical or radiological follow up was sought. All abnormal findings detected with either investigation were confirmed by subsequent imaging studies or by operative procedures. MAIN OUTCOME MEASURE--Accuracy of detection of abnormalities of urinary system by ultrasonography compared with urography. RESULTS--113 Patients (72%) had normal urographic and ultrasonic findings. Overall, ultrasonography concurred with the findings of urography in 149 (94%) patients, and when a single abdominal radiograph was included in the procedure, in 152 (96%). Ultrasonography missed only one important diagnosis, that of mild papillary necrosis in normal sized kidneys in a diabetic patient. It detected one early bladder tumour not visible on urography and was able to clarify the nature of renal masses (simple cysts) evident on three urograms. CONCLUSION--Ultrasonography provides a safe and accurate method of imaging the urinary tract in adults with infection. Combined with a plain abdominal radiograph, it should replace urography as the initial imaging investigation in these patients. Major savings would result from adopting this policy, and the risks to patients from ionising radiation and intravenous contrast media would be appreciably reduced.     

Urinary tract infections in children. An update.

Urinary tract infection is a common and frequently recurring condition in children. The susceptibility of the host, the presence of urinary tract abnormalities, and the virulence of the urinary pathogens are of primary importance in the development of the infection. Renal parenchymal scarring, hypertension, and renal insufficiency are well-established complications of the infection in children. To reduce the risk of renal damage, diagnosis and treatment must be prompt. The diagnosis demands radiologic evaluation of the urinary tract in all boys, all children younger than 5 years, all patients with voiding dysfunction, and school-aged girls with recurrent infection to identify those patients with vesicoureteral reflux, obstruction, or other urinary tract abnormalities. Both voiding cystourethrography and renal ultrasonography are the initial examinations to use to determine the next appropriate study. Children with vesicoureteral reflux or with recurrent urinary tract infections should receive prophylactic antibiotic therapy and should be observed closely to prevent renal scarring.     

Ultrasonography compared with intravenous urography in the investigation of adults with haematuria.

OBJECTIVE--To compare ultrasonography with intravenous urography in the investigation of adults with haematuria. DESIGN--Prospective study entailing the examination of all patients with both investigations concurrently. The investigations were performed independently on routine lists by different duty radiologists. Each was aware of the details of the request form but not of the findings of the other investigation. SETTING--Radiology department of a teaching hospital. PATIENTS--155 Consecutive adult patients (aged 18-93) referred from general practitioners and hospital outpatient clinics with a history of haematuria. FOLLOW UP--When results of both examinations proved normal no clinical or radiological follow up was sought. All abnormal findings of either investigation were correlated with results of subsequent imaging studies or operative findings. RESULTS--81 Patients (52%) had normal findings on urography and ultrasonography. Overall, the findings of ultrasonography concurred with those of urography in 144 cases (93%). Among the discrepant findings of the two investigations ultrasonography missed two ureteric calculi; one was in a non-dilated ureter, and in the other case ultrasonography detected the secondary ureteric dilatation. Ultrasound examination alone detected four bladder tumours not visible on urography with sizes ranging from 5 to 21 mm, representing one fifth of the 20 cystoscopically proved bladder tumours detected in the series. Ultrasonography detected all the 22 neoplastic lesions discovered in the study (20 bladder, two renal). Ultrasonography clarified the nature of renal masses evident in three urograms (simple cysts). CONCLUSIONS--Ultrasonography is a safe and accurate method of investigating the urinary tract in adults with haematuria. When combined with a single plain abdominal radiograph it proved to be superior to urography as the primary imaging study in this series. Ultrasonography should certainly be preferred to urography if cystoscopy is not planned. No urothelial tumours of the upper urinary tract were found in the series, reflecting their rarity. For those patients in whom ultrasonography and plain radiography have shown no abnormality and in whom cystoscopic appearances are normal urography would be advisable to exclude urothelial tumours of the upper urinary tract.     

Retrospective study of children with renal scarring associated with reflux and urinary infection.

OBJECTIVE--To review the histories of children with bilateral renal scarring and severe vesicoureteric reflux to determine whether an improvement in early management might reduce the risk of scarring. DESIGN--Retrospective study of medical records and discussion with parents. SETTING--Outpatient departments of two teaching hospitals. PATIENTS--52 children aged 1-12 years participating in a randomised comparison of medical and surgical management. All had a history of symptomatic urinary tract infection. Two thirds presented with fever and two with hypertension or renal failure. In only one out of 32 children examined by antenatal ultrasonography was an abnormality suspected. RESULTS--There was delay in diagnosis or appropriate imaging or effective treatment of urinary infection in 50 of the 52 children. In 41 there was delay in diagnosis; there was delay in treating a confirmed infection in 45; no antibacterial prophylaxis was prescribed before imaging in 28; and investigation of the urinary tract was delayed in 33. The severity of scarring was significantly related to delay in diagnosis (chi 2 for trend 7.43, P = 0.01). Four children of mothers known to have reflux nephropathy were not investigated until they developed urinary tract infection. CONCLUSIONS--Efforts to reduce the incidence and severity of renal scarring should be directed towards rapid diagnosis and effective early management of urinary tract infection in infancy and childhood. Siblings and offspring of known patients with severe reflux nephropathy should be investigated for reflux.     

Prostatism: how useful is routine imaging of the urinary tract?

The clinical effects of routinely imaging the renal tract (by intravenous urography and ultrasonography) were evaluated prospectively in 128 consecutive patients with prostatism. Patients with haematuria, previous renal disease, or infection were excluded. Urologists completed a standard questionnaire in the patient''s notes stating the diagnosis and the intended management. The patient then had intravenous urography and abdominal ultrasonography, urine was analysed, and plasma urea and serum creatinine concentrations and acid phosphatase activity were determined. From six months to a year later the eventual management was compared with the intended management to see the effect of these routine investigations on the outcome. For four out of 28 patients whose management was intended to be conservative the decision was changed; for only three of them was this because of the results of urography, ultrasonography, and biochemical determinations. For 31 patients the management was to be decided by cystoscopic findings, and for none of these was the final decision altered by the results from the investigations after the initial consultation. Similarly for five patients who were assessed urodynamically the final management was not changed by the results of these investigations. The planned management was changed in three of the remaining 64 patients but not because of the results of the initial investigations.Thus no indication was found for either routine urography or ultrasonography, but the total abandonment of imaging of the renal tract would be unwise. Patients scheduled for conservative management (about a quarter of the patients in this study) should have ultrasonography to detect unsuspected hydronephrosis, but in all other patients urography or ultrasonography, or both, is an unhelpful ritual. Moreover, urography is becoming more expensive, and has a recognised (albeit small) mortality.     

Development of new renal scars: a collaborative study.

In a study of the factors surrounding the development of renal scars clinical data and serial radiographs were analysed in 74 infants and children (66 girls and eight boys) without duplex kidney or obstruction. The development of new scars was seen radiologically in 87 kidneys (74 previously normal and 13 previously scarred). New scarring was extensive in 16 kidneys. Thirty four children were aged 5 or over when scarring occurred. Urinary infection occurred in all the children. Diagnosis and effective treatment were delayed in 45 of them; 58 suffered further urinary infections between the baseline intravenous urogram and the first showing new scarring. Vesicoureteric reflux was seen in 67 of the children. Investigation and treatment varied widely, and few children received long term prophylaxis. Social problems interfered with the management of 22 children. Early diagnosis, prompt effective treatment, investigation, and long term supervision of children with urinary infection are essential if renal scarring is to be reduced; those over the age of 5 are still vulnerable.     

Part II – Roentgenologic Aspects

Roentgen findings in 107 girls under the age of ten years who had proven recurrent urinary tract infections were analyzed. From the excretory urograms done on these children, renal and pelvocalyceal outlines were accurately traced. Subsequently, renal length and parenchymal thickness at multiple points were measured. The presence or absence and grade of reflux were determined by voiding cystourethrography. Finally, the clinical history was correlated with the roentgen findings.With three exceptions, scarring and clubbing in the presence of infection occurred only in refluxing renal units. Kidneys exposed to a higher grade of reflux more frequently showed scarring and clubbing (p<0.001). Seventeen out of 40 renal units either developed or had increase in clubbing and scarring while the patients were being followed. After surgical correction of reflux, 16 of 24 previously clubbed and scarred kidneys showed progression of the lesions, usually within 24 months after operation. All children whose kidneys showed progression after surgical operation had experienced an episode of acute urinary infection with chills and fever before operation.No significant difference existed in the age at clinical onset of infection in patients with ureteral reflux with or without roentgen evidence of clubbing and scarring. This study documents the close relationship between clubbing and scarring and reflux in the presence of urinary infection in infants and children.     

Pregnancies in women with and without renal scarring after urinary infections in childhood.

OBJECTIVE--To compare the outcome of pregnancy in women with and without renal scarring after childhood urinary infections with that in unmatched controls. DESIGN--Retrospective study of pregnancies in women prospectively followed up from their first recognised urinary infection. SETTING--Tertiary referral centre in Gothenburg. SUBJECTS--111 Women attending an outpatient clinic for women with urinary infection during 1975-83, of whom 41 (65 pregnancies) were studied (19 women with renal scarring (32), 22 without scarring (33)), and 65 controls (65) randomly selected and matched for parity, age, smoking habits, and date of delivery. MAIN OUTCOME MEASURES--Urinary infections and complications in pregnancy. RESULTS--The incidence of bacteriuria during first pregnancies was significantly greater in women with (9, 47%) and without (6, 27%) renal scarring after childhood urinary infection than in controls (1, 2%) (p less than 0.001, 0.01 respectively). Symptomatic infections were seen only among women with a history of urinary infection: four women with renal scarring (three of whom had vesicoureteric reflux) developed pyelonephritis and three cystitis, and one woman without scarring developed pyelonephritis. Mean blood pressure was higher among women with severe renal scarring than controls (4/11 v 3/44; p less than 0.05) before and during pregnancy. There was no significant difference in the incidence of pre-eclampsia, operative delivery, prematurity, or birth weight. CONCLUSIONS--Women with a history of previous urinary infections had a high incidence of bacteriuria during pregnancy, and those with renal scarring and persistent reflux were prone to develop acute pyelonephritis. The risk of serious complications in pregnancy, however, was not increased in women with severe renal scarring, possibly owing to their continuous clinical supervision.     

Prospective trial of operative versus non-operative treatment of severe vesicoureteric reflux in children: five years' observation. Birmingham Reflux Study Group.

Children with severe vesicoureteric reflux were allocated randomly to either operative or non-operative treatment and followed up. Altogether 161 children were observed for two years, of whom 104 were followed up for five years. Reflux was abolished in 98% of ureters reimplanted, but more than half of the patients treated non-operatively continued to show severe reflux at five years. Two patients progressed to end stage renal failure, and a further four with extensive bilateral renal scarring became hypertensive. There were no significant differences between treatment groups in the incidence of breakthrough urinary infection, renal excretory function and concentrating ability, renal growth, progression of existing renal scars, or new scar formation. Progressive scarring occurred at all ages but was significantly more common during the first two years'' observation. Furthermore, new scars developed exclusively during the first two years'' observation, affecting 10 children aged 2-7 at allocation. Neither treatment can claim superiority or fully protect the kidneys from further damage, and efforts must continue to be directed towards identifying those at risk before scarring develops.     

Part III – Treatment of Ureterovesical Reflux

Of 134 girls with demonstrable ureterovesical reflux, 61 (105 ureters) had the reflux surgically corrected with an overall surgical cure rate of 97 percent. In the remaining 73 children (112 ureters), the reflux was treated conservatively with medical management alone. During the follow-up period no significant differences were demonstrated in the overall incidence of urinary tract infection; two years following corrective operation or medical treatment more than 50 percent of both medically and surgically treated children were still experiencing infections. A pronounced decrease, however, occurred in the incidence of clinical pyelonephritis among the surgically treated group. Following correction of reflux, the incidence of pyelonephritis was similar in both medically and surgically treated cases and was approximately the same as that found in a comparable group of children without reflux.In approximately two-thirds of refluxing renal units in which there was evidence of clubbing and scarring before medical or surgical therapy, deterioration progressed during the follow-up period. In most of these cases infection control was felt to be inadequate with episodes of clinical pyelonephritis occurring during the period of medical management, or, in the surgically treated group, occurring just before corrective operation and the scar appearing within two years after operation.The majority of renal units in which calyceal clubbing and parenchymal scarring was present had the most severe grades of reflux.     

The role of Tamm-Horsfall protein in the pathogenesis of reflux nephropathy and chronic pyelonephritis

Recurrent bacterial infection of the kidney was previously thought to be responsible for the renal scarring typical of chronic pyelonephritis until recent studies suggested that recurrent bacteriuria rarely produces chronic pyelonephritis in the absence of obstructive uropathy. In contrast, the association between vesicoureteral reflux (VUR) and chronic pyelonephritis has been observed frequently in the absence of urinary infection. Although the mechanism by which VUR injures the kidney has not been defined, recent observations have suggested that some component of urine might serve as an antigenic determinant involved in the immunopathogenesis of renal scarring in VUR. Therefore, the present studies investigated the immunopathogenic role of Tamm-Horsfall protein (THP) in (1) a rabbit model of tubulointerstitial nephritis; (2) a swine model of reflux nephropathy; and (3) patients with recurrent nephrolithiasis. The antigenic similarities between THP and uropathic bacteria were also studied. Our observations indicate that autoimmune responses to THP may occur after exposure to THP by intravenous challenge in rabbits, by urinary reflux in pigs, and in recurrent nephrolithiasis in man. Also, extracts of uropathic coliforms competitively inhibit the binding of human THP to its antibody. These studies suggest that autoimmune responses to THP may be the pathogenetic mechanism by which these factors, including bacteriuria, contribute to "chronic pyelonephritis."     

Ultrasonography of the metacarpophalangeal and proximal interphalangeal joints in rheumatoid arthritis: a comparison with magnetic resonance imaging, conventional radiography and clinical examination

Signs of inflammation and destruction in the finger joints are the principal features of rheumatoid arthritis (RA). There are few studies assessing the sensitivity and specificity of ultrasonography in detecting these signs. The objective of the present study was to investigate whether ultrasonography can provide information on signs of inflammation and destruction in RA finger joints that are not available with conventional radiography and clinical examination, and comparable to the information provided by magnetic resonance imaging (MRI). The second to fifth metacarpophalangeal and proximal interphalangeal joints of 40 RA patients and 20 control persons were assessed with ultrasonography, clinical examination, radiography and MRI. With MRI as the reference method, the sensitivity, specificity and accuracy of ultrasonography in detecting bone erosions in the finger joints were 0.59, 0.98 and 0.96, respectively; they were 0.42, 0.99 and 0.95 for radiography. The sensitivity, specificity and accuracy of ultrasonography, with signs of inflammation on T1-weighted MRI sequences as the reference method, were 0.70, 0.78 and 0.76, respectively; they were 0.40, 0.85 and 0.72 for the clinical examination. With MRI as the reference method, ultrasonography had higher sensitivity and accuracy in detecting signs of inflammation and destruction in RA finger joints than did clinical and radiographic examinations, without loss of specificity. This study shows that ultrasonography has the potential to improve assessment of patients with RA.     

Optimizing the accuracy of detecting a functional corpus luteum in dairy cows

The objectives were to evaluate the accuracy of detecting a functional CL by transrectal palpation and ultrasonography, and to optimize the accuracy of detecting a functional CL by ultrasonography in Holstein cows. In Experiment 1, four veterinarians performed transrectal palpation in 1250 cows at 37 d in milk (DIM), two veterinarians repeated transrectal palpation in 823 cows at 58 DIM, and one veterinarian performed 206 ultrasonographic examinations at 37 DIM. In Experiment 2, 987 and 983 ultrasonographic examinations were performed at 21 and 24 d after AI by one veterinarian for detection and measurement of CL. Cows with a blood progesterone concentration > or =1ng/mL were assumed to have a functional CL. Sensitivity and specificity were optimized using receiver operating characteristic analysis. In Experiment 1, sensitivity of transrectal palpation for diagnosing a functional CL ranged from 33.3 to 59.9% at 37 DIM and from 48.3 to 68.4% at 58 DIM, whereas specificity ranged from 76.7 to 93.2% at 37 DIM and from 73.3 to 86.7% at 58 DIM. Sensitivity and specificity for ultrasonography were 89.4 and 45.7%, respectively. In Experiment 2, the sensitivity and specificity of ultrasonography were 97.3 and 38.1% at 21 d after AI, and were 97.9 and 51.0% at 24 d after AI. Sensitivity and specificity were optimized using a cutoff diameter of 23mm at 21 d and 22mm at 24 d, which resulted in sensitivity and specificity of 87.2 and 83.0% at 21 d, and 89.5 and 89.4% at 24 d after AI, respectively. Sensitivity was low and specificity was high for transrectal palpation, whereas ultrasonography resulted in high sensitivity and low specificity. Using a cutoff diameter during ultrasonography improved accuracy of detection of a functional CL compared with either ultrasonography without cutoff or transrectal palpation.     

City-wide screening for urinary abnormalities in schoolboys

Screening for urinary tract infection was carried out in 27,722 schoolboys aged 5 to 14 using Uricult to perform urine cultures and Hema-combistix to detect hematuria, proteinuria and glycosuria. Cultures of 10⁵ colonies per ml or more on two occasions were found in 40 cases (0.14%), but no case was confirmed by the family physician using standard culture techniques.Proteinuria was found in 136 cases (0.49%) and confirmed in 47 (37%) of the 126 children who were seen by their family physician. In this group 8.8% had evidence of pyelonephritic scarring on intravenous pyelograms without a positive urine culture.Hematuria was found in 19 children and confirmed in 10 (59%) of the 17 children who were seen by their family physician. No abnormalities were detected on intravenous pyelography in any case.Glycosuria was found in 12 cases and confirmed in five. Three of these children had renal glycosuria and two had previously undetected diabetes.     

Clinical importance of significant asimptomatic bacteriuria in newborns and infants during early postnatal period

The aim of the study was to detect newborns at risk for developing renal impairment, and to point out the importance of significant asimptomatic bacteriuria in perinatal period and early infancy. Severe urinary tract anomalies are very often accompanied only by asimptomatic bacteriuria in perinatal period. Three urinalysis ware done after delivery. 212 newborns with significant asimptomatic bacteriuria underwent ultrasound examination, and were followed up to three months. Those with normal findings and with passing bacteriuria in the first 2 months were excluded. Group of 52 newborns underwent radioisotope examination. Frequency of urinary tract anomalies in newborns was 34.6%. Increased risk for renal impairment had children with urinary tract anomalies in close family, urinary tract infection or bacteriuria, EPH gestosis and prepartal symptoms of febrile infection in mother, children with IUGR, strangulated umbilical cord, prolonged jaundice and attacks of peripheral cyanosis in perinatal period.     

Difficulties in the diagnosis of pheochromocytoma in children]

Pheochromocytoma was the cause of arterial hypertension observed in 0.9% of children treated in 1982-1989. Out of clinical features the most characteristic was sustained hypertension often complicated by the accelerated phase of malignant hypertension and encephalopathy. Sustained tachycardia was also found in all patients. Increased urinary excretion of catecholamines and its metabolites confirmed the diagnosis in all cases. The most sensitive and specific methods for tumor diagnosis were ultrasonography and computer tomography of the adrenals while scintigraphy with meta-iodobenzylguanidine+ labelled with iodine-131 radioisotope gave a high percentage of false negative results.     

Secretor state and renal scarring in girls with recurrent pyelonephritis

Abstract The non-secretor phenotype was significantly associated with the occurrence of renal scarring among patients with recurrent pyelonephritis. Girls ( n = 77) with recurrent pyelonephritis were followed from the first known episode of infection for up to twelve years with repeated radiological investigations. They were divided into two categories: those with renal scars ( n = 35) and those who did not develop scars ( n = 42). There was a significant over-representation of non-secretors among the patients with scarring, (14/35, 40%) compared to the healthy controls (21.8%, P < 0.05). The frequency of non-secretors among the girls who did not develop scars in spite of repeated episodes of acute pyelonephritis was not significantly different from the healthy controls (9/42, 21%, n.s.). This study provides a basis for analysis of the influence of secretor state on host-parasite interaction in the urinary tract.     

The significance of ultrasonography in diagnosing and follow-up of cystic cystitis in children

Cystic cystitis is a separate form of urinary bladder inflammation, detected by cystoscopy in children with recurrent urinary infections. Cystoscopy is an invasive method, so the aim of this investigation was to determine the ultrasonographic characteristics of cystic cystitis and to assess the reliability of ultrasound in relation to cystoscopy in diagnosing cystic cystitis. The study included 115 girls with repeated urinary infections. Cystoscopy and ultrasonography was performed in all. According to the cystoscopic finding the subjects were divided into 4 groups. Lateral and posterior urinary bladder wall thickness was measured during ultrasonography. A statistically significant difference was found between all 4 groups, the method demonstrated a high degree of sensitivity (0.97) and specificity (0.91). Percentile calculations were determined for wall thickness. Ultrasonography can replace endoscopy in diagnosis and follow-up of cystic cystitis in children, with at least 50% fullness of the urinary bladder as a prerequisite.