Urinary tract infections (UTIs) in children are common and a major source of morbidity. The incidence of UTIs in childhood is not precisely known because it is not a reportable disease, and in many cases, especially in infants, UTIs are underdiagnosed. Furthermore, the definitions and criteria for diagnosis vary considerably. This article reviews the diagnosis and work-up of UTIs in children, and presents current data reviewing the roles of radiologic imaging, surgical correction, and antibiotic prophylaxis in the setting of pediatric UTIs.
Urinary tract infections (UTIs) in children are common and a major source of morbidity. The incidence of UTIs in childhood is not precisely known because it is not a reportable disease, and in many cases, especially in infants, UTIs are probably underdiagnosed. Furthermore, the definitions and criteria for diagnosis vary considerably; for example, should children with asymptomatic bacteriuria be included, or what criteria should be used to diagnose a UTI when the urine is obtained with a bagged urine specimen . Nonetheless, it has been estimated that 7% of girls and 2% of boys have a UTI prior to age 6 . During the first year of life more boys than girls are diagnosed with a UTI, with uncircumcised boys having a 10-fold greater risk than those circumcised . This trend reverses after the first year of life, with more girls than boys being diagnosed with a UTI.
Pediatric UTIs constitute a significant health burden, although the actual costs are not known . In the United States, overall inpatient hospital costs are estimated to be greater than $180 million alone. This fails to include the costs of follow-up, including imaging, or the costs to society of parents losing productivity for diagnosis, treatment, and follow-up of their child’s infection .
This article reviews the diagnosis and work-up of UTIs in children, and presents current data reviewing the roles of radiologic imaging, surgical correction, and antibiotic prophylaxis in the setting of pediatric UTIs.
Diagnosis of urinary tract infections in children
Early and rapid diagnosis is paramount to initiating prompt antimicrobial therapy and thereby limiting renal damage. In children, however, the diagnosis is in no way straightforward. UTIs are found in more than 5% of infants and young children who have no source of fever from history or physical examination , and in another study of febrile infants, 13.6% were found to have infections of the urine. The symptoms of a UTI in young children, however, are very nonspecific. Rarely are symptoms referable to the urinary tract observed. Even in older children UTIs rarely present with dysuria (more likely a sign of introital irritation) or urgency. Instead, frequency and urgency may be manifest as new-onset or increased incontinence. Likely, many UTIs are either not diagnosed or diagnosed late. Because the symptoms can be quite obscure, it is important that primary care providers have a high index of suspicion for UTIs in children .
It is well recognized that a well-collected urinary specimen is critical to make the diagnosis of infection; however, a noncontaminated specimen is hard to obtain in children. There are four ways that urine may be obtained: (1) a bagged specimen, where a bag is taped to the perineum and urine obtained after the child voids (obviously useful in infants, but there is a high risk of obtaining a contaminated sample); (2) a midstream collection (unreliable in children, especially young girls and uncircumcised boys in whom contaminated samples are likely) is useful if negative, but if positive, it is hard to tell whether the collection was contaminated; (3) a catheterized specimen (obviously traumatic in children and further, in the uncooperative girl it can easily be contaminated); and (4) suprapubic aspiration (clearly the least likely to be contaminated, but again, traumatic in children and rarely practiced in the current, litigious environment).
Four determinants from the urinalysis have been accepted as supporting a UTI: (1) positive urinary leukocyte esterase on dipstick (revealing the presence of white blood cells in the urine), which has a sensitivity and specificity of about 75% ; (2) positive urinary nitrite on dipstick (dietary nitrates are reduced to nitrite by many gram-negative urinary bacteria), the sensitivity is low at 60% although the specificity approaches 100% ; (3) more than five white blood cells per high-powered field on microscopic examination of the spun urinary sediment; and (4) any bacteria seen on a high-powered examination of the spun urinary sediment. The presence of any bacteria on Gram stain has a sensitivity of 93% and specificity of 95%, better than dipstick evaluation for leukocyte esterase and nitrite . Microscopic examination of the sediment can also reveal epithelial cells (strongly suggestive of contamination) or white blood cell casts (pathognomonic of pyelonephritis) .
The urine culture is a critical part of the work-up for a presumed UTI. The culture identifies the organism causing the infection and helps guide treatment with the correct antibiotics. The traditional definition for a clinically significant UTI is more than 100,000 cfu/mL . Lower numbers have also been shown to correlate with a UTI, especially when obtained by suprapubic aspirate. Lower numbers can also constitute a UTI because of additional factors (eg, hydrational dilution and frequent voiding) .
Distinguishing upper from lower tract urinary tract infections
Traditionally, clinical grounds have been used to distinguish pyelitis and pyelonephritis from cystitis. In particular, when urinary frequency and dysuria are accompanied by flank pain and a high-grade fever (>38.5°C) and rigors, this suggests the diagnosis of pyelonephritis . These clinical findings are not entirely reliable, however, in identifying that the kidney is involved. Similarly, urinalysis, C-reactive protein, and erythrocyte sedimentation rate have low predictive value. More recently, there has been interest in identifying new markers to help identify acute pyelonephritis.
Cytokines are small proteins that help initiate the inflammatory process and have been identified as markers of infections and inflammation. The most recognized are tumor necrosis factor-α and interleukin-6 . Although initially promising as markers of upper tract infection, they were ultimately shown to have low sensitivity and specificity for upper tract infections.
More promising is procalcitonin (PCT). PCT is a polypeptide identical to the prohormone of calcitonin that has been described as a potential marker for biologic disease . PCT is a 116-amino acid propeptide of calcitonin that lacks hormonal activity. Plasma concentrations in healthy subjects, chronic inflammatory states, viral infections, and autoimmune disease are below 0.5 ng/mL. In moderate localized bacterial infection PCT ranges from 0.5 to 2, and in severe gram-negative bacterial infections with sepsis and multiorgan failure the level is found to be above 2 ng/mL .
Bacterial cells produce a cell wall, and all bacterial cell walls contain peptidoglycan. Gram-negative bacteria contain an extra layer in the cell wall structure called the outer membrane, which is outside the peptidoglycan layer. Endotoxin is a component of this outer membrane and is released in gram-negative infections. The most common organisms associated with UTI and pyelonephritis are the gram-negative bacteria Escherichia coli , Proteus sp, and Pseudomonas sp, which all produce endotoxin. Gram-positive organisms including Staphylococcus aureus and Enterococcus faecalis are also known to cause pyelonephritis but do not form or release endotoxin . It has been shown that PCT is present in the serum 2 to 6 hours after the release of bacterial endotoxin into the bloodstream and its half-life in serum ranges from 24 to 30 hours . The plasma concentration of PCT reaches a peak in 6 hours and stays high as long as the infectious stimulus is present. Because of its relatively short half-life, a rapid downfall is apparent by 48 hours after successful antibiotic treatment .
Correlations between PCT and pyelonephritis have now been well demonstrated. PCT levels have been found to be increased significantly in children with febrile UTI, and levels greater than 0.5 ng/mL were found when renal parenchyma involvement was present . PCT has also been evaluated to distinguish risk of scarring in the setting of UTI. In those with UTI and no scarring, PCT levels remained low. In contrast, those with renal scarring had elevated initial PCT levels that remained elevated for at least 24 hours . Further large multicenter studies are needed to validate the previous studies, determine its use in gram-positive infections, and better delineate sensitivity and specificity rates, but PCT is promising as a useful tool in differentiating pyelonephritis from cystitis in children.
Renal imaging
It has long been recognized that UTIs in the pediatric population may serve as a marker for anatomic abnormalities. Obstructive lesions are found in 5% to 10% of children with reflux and in 21% to 57% of children with UTIs . Hence, imaging has been thought to be appropriate after the diagnosis of a UTI in a young child. There has been considerable controversy, however, over which children to image. A consensus published in the Journal of Pediatrics in 1999 provided practice parameters for infants and young children 2 months to 2 years of age with UTIs. These guidelines stated that infants and young children 2 months to 2 years of age with UTIs who do not demonstrate the expected clinical response within 2 days of antimicrobial therapy should undergo ultrasonography promptly, and either voiding cystourethrography (VCUG) or radionuclide cystography should be performed at the earliest convenient time, and young children 2 months to 2 years of age with UTIs who have the expected response to antimicrobials should have a sonogram and either VCUG or radionuclide cystography performed at the earliest convenient time .
Ultrasound
Ultrasonography can be used to identify many renal abnormalities, such as abnormalities of renal size and shape, duplication anomalies, hydronephrosis, or hydroureters. The bladder is also evaluable with ultrasound and may show thickening or the presence of other abnormalities like bladder diverticula or ureteroceles . These findings may diagnose an abnormality or may suggest a problem like vesicoureteral reflux (VUR). Further, Doppler ultrasonography (and so-called power Doppler ultrasonography) can also be used to detect small areas of inflammation within the kidney, essentially diagnosing acute pyelonephritis. Unfortunately, the sensitivity and specificity of ultrasound for acute pyelonephritis is not very good . An important caveat of renal-bladder ultrasound is that it is dependent on the skill of the operator, so it is important to have technicians and radiologists who have experience with both ultrasound and pediatric patients .
Even so, it has been argued that ultrasound may not be needed after UTIs in young children, perhaps because many have had prenatal ultrasounds that have demonstrated normal kidneys . The authors’ study of their population has confirmed that ultrasound remains a highly useful study. In their experience, it altered the diagnosis and treatment in at least 4.4% of patients . Because it is noninvasive and radiation free, it is an excellent study in young children with UTIs.
Voiding cystourethrogram
Because VUR is seen in up to 50% of children with pyelonephritis, a VCUG has been thought to be a most important examination for children with clinical pyelonephritis. It has been shown that normal children have a very low rate of VUR (<1%), whereas those with pyelonephritis have a much higher rate . The test is considered invasive because it requires urethral catheterization. Because of this, parents and pediatricians have for many years questioned its necessity. Many techniques have been tested for reducing the trauma of the test, including hypnosis and sedation with midazolam . Because these techniques greatly increase the time, cost, and risk of the test, they have not been widely adopted.
Radiation exposure has also been an issue. The test may be done with either traditional fluoroscopic techniques or with a radioisotope . The radionuclide cystogram has traditionally had approximately 1/100th of the radiation exposure. Further, because imaging is continuous with a radionuclide cystogram (versus intermittent with fluoroscopy), it seems to be more sensitive in determining reflux than a traditional contrast VCUG . Fluoroscopic VCUG is more accurate at grading reflux, however, and can show spinal abnormalities, bladder and urethral anatomy, periureteral diverticula, and other upper tract detail that cannot be identified with radionuclide cystography . Traditionally, fluoroscopic VCUG has been the choice over radionuclide cystography in boys where urethral abnormalities may be present and for the initial study in girls . More recently, new fluoroscopic equipment and tailored techniques have reduced the difference in radiation exposure and have led to more widespread adoption of the traditional VCUG . Ultrasonographic techniques, including using microbubbles as a contrast agent, have been attempted, but have not been found to be useful . Similarly, techniques that avoid catheterization, including ultrasound and indirect radionuclide methodologies, have not been found to be useful . In the authors’ experience, the traditional fluoroscopic VCUG remains an important study for children with febrile UTIs.
Tc 99m dimercaptosuccinic acid renal scanning
A positive urine culture is the gold standard for identifying a UTI. Determining whether the infection affects the kidneys, however, has been difficult. Radionuclide scanning using Tc 99m dimercaptosuccinic (DMSA) has become readily available and is used in many centers to help diagnose acute pyelonephritis .
Renal scintigraphy using DMSA has been shown to be accurate in detecting acute pyelonephritis and renal scarring in both animal models of acute pyelonephritis and in humans . DMSA when injected intravenously binds to renal proximal tubular cells, and when radiolabeled, renal cortical images can be obtained 2 to 4 hours later. An area of decreased uptake in the kidney represents an area of abnormal or damaged renal tubular cells. These radionuclide scans have been compared with histopathology specimens, have an overall sensitivity and specificity of 86% and 91% for diagnosing acute pyelonephritis in animal studies, and have theoretical benefits over other types of studies for this purpose .
Scans may be used in the acute setting to determine the degree and site of involvement of a UTI. Many initial DMSA defects, however, resolve on follow-up. DMSA scans also may be used to determine the presence and extent of permanent damage (scarring) after an episode of pyelonephritis by imaging several months after the infection. DMSA scans have been shown to be several times more sensitive in the detection of renal scarring than the intravenous pyelogram or ultrasound . Although the study is associated with relatively high doses of radiation to the kidneys, the radiation exposure to the ovaries and bone marrow is minimal . CT has been proposed as an alternative, but is thought to have higher radiation exposure overall .
Although clearly the best study for determining the presence of renal scarring, the role of DMSA scanning has come into question. In an era of cost-benefit analysis, the question is whether the results of the study alter management. In most cases the answer is no, hence the study may not be needed. The presence of scarring, however, may be an indication that reflux is more likely to persist and the study may be beneficial for this purpose. A study supporting the use of DMSA scanning revealed abnormal scans in 42% of patients with first-time UTIs and in 55% of patients with recurrent UTIs . Three categories of abnormalities were noted: (1) renal cortical defects, (2) dilated pelvicalyceal system, and (3) renal swelling showing disproportionate function compared with size. The study concluded that the high yield of renal abnormalities by Tc 99m DMSA scanning emphasizes the importance of scanning all cases of UTIs, including patients with a first-time infection. The authors concluded that the pattern of abnormalities in the scan may help in planning for subsequent management of UTIs in these patients .
In further support of DMSA scanning, Nguyen and coworkers compared renal ultrasound results with DMSA results in 34 patients with known sterile reflux. The study found most infants with high-grade reflux had decreased differential function or cortical defects on DMSA. Parenchymal defects detected by Tc 99m DMSA renal scintigraphy were often not identified by renal ultrasound. The study concluded that Tc 99m DMSA renal scintigraphy is especially useful for initially evaluating infants with high-grade, sterile VUR. Further, several studies have demonstrated that renal status, as documented by radionuclide scanning, is predictive of reflux resolution, with normal kidneys being associated with a higher rate of reflux resolution .
In Wales, a DMSA scan is a mandatory part of the work-up for a UTI in those children less than 7 years of age. A study out of Wales, however, questioned the validity of DMSA scanning in children greater than 1 year old because only 2% of those children were found to have renal scarring. Their final conclusion was that only those children with signs of pyelonephritis should undergo a DMSA scan .
Recommendations for imaging
At this time, guidelines at Albany Medical Center for imaging in the pediatric community following UTI are as follows:
Routine tailored VCUG for
- •
Children younger than 5 years of age with a febrile UTI
- •
Males of any age with a first UTI
- •
Girls younger than the age of 2 years with a first UTI
- •
Children with recurrent UTI
- •
Renal ultrasonography for
- •
Children younger than 5 years old with a febrile UTI
- •
Males of any age with a first UTI
- •
Girls younger than the age of 3 years with a first UTI
- •
Children with recurrent UTI
- •
Children with a UTI who do not respond promptly to therapy to determine whether a renal abscess or obstruction is present
- •
Routine DMSA scanning
- •
DMSA scanning is warranted in selected cases in which the diagnosis of UTI is uncertain on account of equivocal urinalysis or culture results (eg, in patients receiving antimicrobial therapy at the time the urine culture is obtained) and in newborns with reflux
- •
Follow-up scintigraphy to establish the presence of scarring is not routinely necessary, because the significance and management of scarring seen only on a DMSA scan has not been studied adequately; however, in high-risk populations, such as infants with febrile UTIs or those children with high-grade reflux, this study may well have prognostic significance
- •
New and somewhat experimental approaches to imaging
There are some new ideas, primarily as regards the use of VCUGs. There is an effort to avoid or at least limit their use. One approach is to use DMSA scanning and ultrasound acutely. If the DMSA scan shows a renal injury, a VCUG is needed. If the DMSA is negative, even acutely after a clinical episode of pyelonephritis, it suggests that scarring in the future is unlikely . Hence, some argue that a VCUG is unnecessary. In theory, if the principal reason for diagnosing and treating reflux is to prevent scarring, then there is no need to diagnose or treat reflux in those cases. If there is a normal DMSA scan, no VCUG is necessary in those cases. Some argue that these patients, even if they do not get scarring, likely will have recurrent pyelonephritis and it is worthwhile to diagnose reflux in these patients, if only to put them on prophylactic antibiotics for a period of time (see later).
Another approach is to increase the time between VCUGs in children with known reflux. Traditionally, studies have been performed annually to evaluate for resolution of reflux. It has been proposed that every 2 years is a more reasonable approach and this limits both catheterization and radiation exposure in the child .
Finally, there is limited information on what to expect in a child who has had a complete radiographic work-up that is negative. The authors found that about 20% of these children will have recurrent UTIs despite negative radiologic evaluation. Although not statistically significant, there is a trend for an increased recurrence risk in girls and particularly those with a history of recurrent febrile illnesses . The significance of these recurrent infections has not been determined.
Renal imaging
It has long been recognized that UTIs in the pediatric population may serve as a marker for anatomic abnormalities. Obstructive lesions are found in 5% to 10% of children with reflux and in 21% to 57% of children with UTIs . Hence, imaging has been thought to be appropriate after the diagnosis of a UTI in a young child. There has been considerable controversy, however, over which children to image. A consensus published in the Journal of Pediatrics in 1999 provided practice parameters for infants and young children 2 months to 2 years of age with UTIs. These guidelines stated that infants and young children 2 months to 2 years of age with UTIs who do not demonstrate the expected clinical response within 2 days of antimicrobial therapy should undergo ultrasonography promptly, and either voiding cystourethrography (VCUG) or radionuclide cystography should be performed at the earliest convenient time, and young children 2 months to 2 years of age with UTIs who have the expected response to antimicrobials should have a sonogram and either VCUG or radionuclide cystography performed at the earliest convenient time .
Ultrasound
Ultrasonography can be used to identify many renal abnormalities, such as abnormalities of renal size and shape, duplication anomalies, hydronephrosis, or hydroureters. The bladder is also evaluable with ultrasound and may show thickening or the presence of other abnormalities like bladder diverticula or ureteroceles . These findings may diagnose an abnormality or may suggest a problem like vesicoureteral reflux (VUR). Further, Doppler ultrasonography (and so-called power Doppler ultrasonography) can also be used to detect small areas of inflammation within the kidney, essentially diagnosing acute pyelonephritis. Unfortunately, the sensitivity and specificity of ultrasound for acute pyelonephritis is not very good . An important caveat of renal-bladder ultrasound is that it is dependent on the skill of the operator, so it is important to have technicians and radiologists who have experience with both ultrasound and pediatric patients .
Even so, it has been argued that ultrasound may not be needed after UTIs in young children, perhaps because many have had prenatal ultrasounds that have demonstrated normal kidneys . The authors’ study of their population has confirmed that ultrasound remains a highly useful study. In their experience, it altered the diagnosis and treatment in at least 4.4% of patients . Because it is noninvasive and radiation free, it is an excellent study in young children with UTIs.
Voiding cystourethrogram
Because VUR is seen in up to 50% of children with pyelonephritis, a VCUG has been thought to be a most important examination for children with clinical pyelonephritis. It has been shown that normal children have a very low rate of VUR (<1%), whereas those with pyelonephritis have a much higher rate . The test is considered invasive because it requires urethral catheterization. Because of this, parents and pediatricians have for many years questioned its necessity. Many techniques have been tested for reducing the trauma of the test, including hypnosis and sedation with midazolam . Because these techniques greatly increase the time, cost, and risk of the test, they have not been widely adopted.
Radiation exposure has also been an issue. The test may be done with either traditional fluoroscopic techniques or with a radioisotope . The radionuclide cystogram has traditionally had approximately 1/100th of the radiation exposure. Further, because imaging is continuous with a radionuclide cystogram (versus intermittent with fluoroscopy), it seems to be more sensitive in determining reflux than a traditional contrast VCUG . Fluoroscopic VCUG is more accurate at grading reflux, however, and can show spinal abnormalities, bladder and urethral anatomy, periureteral diverticula, and other upper tract detail that cannot be identified with radionuclide cystography . Traditionally, fluoroscopic VCUG has been the choice over radionuclide cystography in boys where urethral abnormalities may be present and for the initial study in girls . More recently, new fluoroscopic equipment and tailored techniques have reduced the difference in radiation exposure and have led to more widespread adoption of the traditional VCUG . Ultrasonographic techniques, including using microbubbles as a contrast agent, have been attempted, but have not been found to be useful . Similarly, techniques that avoid catheterization, including ultrasound and indirect radionuclide methodologies, have not been found to be useful . In the authors’ experience, the traditional fluoroscopic VCUG remains an important study for children with febrile UTIs.
Tc 99m dimercaptosuccinic acid renal scanning
A positive urine culture is the gold standard for identifying a UTI. Determining whether the infection affects the kidneys, however, has been difficult. Radionuclide scanning using Tc 99m dimercaptosuccinic (DMSA) has become readily available and is used in many centers to help diagnose acute pyelonephritis .
Renal scintigraphy using DMSA has been shown to be accurate in detecting acute pyelonephritis and renal scarring in both animal models of acute pyelonephritis and in humans . DMSA when injected intravenously binds to renal proximal tubular cells, and when radiolabeled, renal cortical images can be obtained 2 to 4 hours later. An area of decreased uptake in the kidney represents an area of abnormal or damaged renal tubular cells. These radionuclide scans have been compared with histopathology specimens, have an overall sensitivity and specificity of 86% and 91% for diagnosing acute pyelonephritis in animal studies, and have theoretical benefits over other types of studies for this purpose .
Scans may be used in the acute setting to determine the degree and site of involvement of a UTI. Many initial DMSA defects, however, resolve on follow-up. DMSA scans also may be used to determine the presence and extent of permanent damage (scarring) after an episode of pyelonephritis by imaging several months after the infection. DMSA scans have been shown to be several times more sensitive in the detection of renal scarring than the intravenous pyelogram or ultrasound . Although the study is associated with relatively high doses of radiation to the kidneys, the radiation exposure to the ovaries and bone marrow is minimal . CT has been proposed as an alternative, but is thought to have higher radiation exposure overall .
Although clearly the best study for determining the presence of renal scarring, the role of DMSA scanning has come into question. In an era of cost-benefit analysis, the question is whether the results of the study alter management. In most cases the answer is no, hence the study may not be needed. The presence of scarring, however, may be an indication that reflux is more likely to persist and the study may be beneficial for this purpose. A study supporting the use of DMSA scanning revealed abnormal scans in 42% of patients with first-time UTIs and in 55% of patients with recurrent UTIs . Three categories of abnormalities were noted: (1) renal cortical defects, (2) dilated pelvicalyceal system, and (3) renal swelling showing disproportionate function compared with size. The study concluded that the high yield of renal abnormalities by Tc 99m DMSA scanning emphasizes the importance of scanning all cases of UTIs, including patients with a first-time infection. The authors concluded that the pattern of abnormalities in the scan may help in planning for subsequent management of UTIs in these patients .
In further support of DMSA scanning, Nguyen and coworkers compared renal ultrasound results with DMSA results in 34 patients with known sterile reflux. The study found most infants with high-grade reflux had decreased differential function or cortical defects on DMSA. Parenchymal defects detected by Tc 99m DMSA renal scintigraphy were often not identified by renal ultrasound. The study concluded that Tc 99m DMSA renal scintigraphy is especially useful for initially evaluating infants with high-grade, sterile VUR. Further, several studies have demonstrated that renal status, as documented by radionuclide scanning, is predictive of reflux resolution, with normal kidneys being associated with a higher rate of reflux resolution .
In Wales, a DMSA scan is a mandatory part of the work-up for a UTI in those children less than 7 years of age. A study out of Wales, however, questioned the validity of DMSA scanning in children greater than 1 year old because only 2% of those children were found to have renal scarring. Their final conclusion was that only those children with signs of pyelonephritis should undergo a DMSA scan .
Recommendations for imaging
At this time, guidelines at Albany Medical Center for imaging in the pediatric community following UTI are as follows:
Routine tailored VCUG for
- •
Children younger than 5 years of age with a febrile UTI
- •
Males of any age with a first UTI
- •
Girls younger than the age of 2 years with a first UTI
- •
Children with recurrent UTI
- •
Renal ultrasonography for
- •
Children younger than 5 years old with a febrile UTI
- •
Males of any age with a first UTI
- •
Girls younger than the age of 3 years with a first UTI
- •
Children with recurrent UTI
- •
Children with a UTI who do not respond promptly to therapy to determine whether a renal abscess or obstruction is present
- •
Routine DMSA scanning
- •
DMSA scanning is warranted in selected cases in which the diagnosis of UTI is uncertain on account of equivocal urinalysis or culture results (eg, in patients receiving antimicrobial therapy at the time the urine culture is obtained) and in newborns with reflux
- •
Follow-up scintigraphy to establish the presence of scarring is not routinely necessary, because the significance and management of scarring seen only on a DMSA scan has not been studied adequately; however, in high-risk populations, such as infants with febrile UTIs or those children with high-grade reflux, this study may well have prognostic significance
- •
New and somewhat experimental approaches to imaging
There are some new ideas, primarily as regards the use of VCUGs. There is an effort to avoid or at least limit their use. One approach is to use DMSA scanning and ultrasound acutely. If the DMSA scan shows a renal injury, a VCUG is needed. If the DMSA is negative, even acutely after a clinical episode of pyelonephritis, it suggests that scarring in the future is unlikely . Hence, some argue that a VCUG is unnecessary. In theory, if the principal reason for diagnosing and treating reflux is to prevent scarring, then there is no need to diagnose or treat reflux in those cases. If there is a normal DMSA scan, no VCUG is necessary in those cases. Some argue that these patients, even if they do not get scarring, likely will have recurrent pyelonephritis and it is worthwhile to diagnose reflux in these patients, if only to put them on prophylactic antibiotics for a period of time (see later).
Another approach is to increase the time between VCUGs in children with known reflux. Traditionally, studies have been performed annually to evaluate for resolution of reflux. It has been proposed that every 2 years is a more reasonable approach and this limits both catheterization and radiation exposure in the child .
Finally, there is limited information on what to expect in a child who has had a complete radiographic work-up that is negative. The authors found that about 20% of these children will have recurrent UTIs despite negative radiologic evaluation. Although not statistically significant, there is a trend for an increased recurrence risk in girls and particularly those with a history of recurrent febrile illnesses . The significance of these recurrent infections has not been determined.
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