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Indications for cystography in children. Morphological abnormalities and functional defects
Víctor M García Nieto1, María Candelaria Darias Martin2, Teresa Moraleda Mesa3
1Sección de Nefrología Pediátrica, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Tenerife, Spain.
Insights
Basic kidney function tests can help determine if children need cystography after a urinary tract infection (UTI). Maximum urinary osmolality (UOsm) is useful for ruling out severe vesicoureteral reflux (VUR) in children without a UTI history.
Area of Science:
- Pediatric Nephrology
- Diagnostic Imaging
- Urology
Background:
- Cystography and urethrography were standard after a first UTI, but indications are now clinical.
- Ultrasound is widely used for assessing urinary tract abnormalities.
- Kidney function tests can potentially refine cystography indications in children.
Purpose of the Study:
- To evaluate the role of basic kidney function tests in guiding cystography decisions in pediatric patients.
- To assess the diagnostic accuracy of kidney function tests in identifying vesicoureteral reflux (VUR).
Main Methods:
- A cross-sectional study of 175 children undergoing ultrasound for UTIs or morphological abnormalities.
- Assessed maximum urinary osmolality (UOsm), and urinary albumin/creatinine and NAG/creatinine ratios.
- Defined significant morphological abnormalities (SMAs) based on pelvic diameter.
Main Results:
- Vesicoureteral reflux (VUR) was found in 57 children; 56.1% had SMAs, and 75% had abnormal UOsm.
- "UTI + significant SMA" had an 89% negative predictive value for VUR.
- Combining "SMAs or reduced maximum UOsm" predicted all severe VUR cases (grades IV-V).
Conclusions:
- In children with UTI and SMAs, maximum UOsm testing may not be necessary before cystography.
- Maximum UOsm is valuable for excluding severe VUR in children without a UTI history.
- Renal tubular function tests, alongside clinical and sonographic data, can optimize cystography indications.
Objective:
Until the introduction of ultrasound in clinical practice, routine performance of a cystography and urethrography was the standard of care following a first urinary tract infection (UTI). Current indications for this technique are based on clinical features, age or sex. This study aims to assess the importance of basic kidney function tests in determining the indication for cystography in the pediatric population.
Patients And Methods:
We conducted a cross-sectional observational and analytical, diagnostic accuracy study in 175 children who underwent ultrasound examinations for assessment of morphological abnormalities or with a history of one or more UTIs. We applied the term "significant morphological abnormalities" (SMAs) excluding cases with an anteroposterior diameter of the pelvis of less than 2 cm. The basic kidney function tests used in the assessment were the maximum urinary osmolality (UOsm) and urinary albumin/creatinine and NAG/creatinine ratios.
Results:
The number of patients with normal cystography was 118; the remaining 57 had vesicoureteral reflux (VUR). We found a statistically significant association between UTI and VUR. Significant morphological abnormalities were present in 32/57 cases of VUR (56.1%) and the maximum UOsm was abnormal in 75% of cases with VUR (43/57). The association of "UTI + significant SMA" offered a negative predictive value (NPV) of 89% and a positive predictive value of 49%, leaving two cases of grade IV VUR undiagnosed. The association of UTI with "SMAs or reduced maximum UOsm" predicted all severe cases of VUR (grades IV-V).
Conclusions:
In children who have had UTI, in the presence of SMAs, prior determination of the maximum UOsm does not seem necessary to indicate a cystography. In patients who have not suffered from UTI, determining the maximum UOsm is useful for ruling out the presence of severe VUR. Renal tubular function tests, combined with other clinical, laboratory and sonographic variables, can guide decision-making to avoid unnecessary cystography.
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