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Vesicoureteral reflux in infants
1Department of Pediatric Surgery, Sahlgrenska University Hospital Ostra, Gothenburg, Sweden.
Insights
High-grade vesicoureteral reflux (VUR) in infants differs significantly between males and females. Male infants often show hypercontractile bladder patterns, while females exhibit high capacity, suggesting sex-specific management for VUR.
Area of Science:
- Pediatric Urology
- Nephrology
- Developmental Biology
Background:
- Grade 5 vesicoureteral reflux (VUR) is predominantly observed in male infants, often associated with renal damage.
- In females, high-grade VUR is rare, with typically less severe, focal kidney damage.
Purpose of the Study:
- To investigate sex-based differences in bladder function and pathogenesis of VUR in infants.
- To evaluate the spontaneous resolution rates of VUR and inform treatment timing.
Main Methods:
- Urodynamic studies and free voiding assessments were used to analyze bladder function in male and female infants with VUR.
- Retrospective analysis of prenatally diagnosed VUR cases to determine resolution rates.
Main Results:
- Male infants with dilating reflux often present with hypercontractile bladders, progressing to high-capacity, underfilling bladders.
- Female infants rarely show hypercontractility; they typically have high-capacity bladders with increased residual urine.
- A significant spontaneous resolution rate (40%) of grades 4 and 5 VUR was observed in the first two years for prenatally diagnosed cases.
Conclusions:
- Infant VUR exhibits distinct urodynamic patterns and potential pathogenetic differences between sexes.
- Delayed surgical intervention for VUR in infants may be warranted due to high spontaneous resolution rates.
Abstract:
Grade 5 vesicoureteral reflux (VUR) is almost exclusively seen in male infants, and in one-third of cases occurring with a generalized small kidney with decreased renal function without a previous history of urinary tract infection. In females, however, high-grade reflux is rare and kidney damage almost always less severe and of the focal type, as in older children. Assessment of the bladder function with urodynamic and free voiding studies also indicates a difference between male and female reflux during infancy. Half of the males with dilating reflux initially have a hypercontractile urodynamic pattern indicating small functional capacity with high voiding pressures and often instability during filling. This pattern changes during the first couple of years to high-capacity overdistended bladders, often with incomplete emptying. In females, hypercontractility is seldom seen, but bladder function is characterized by high capacity and there is an increase in residual urine from presentation. The pathogenesis of VUR has also been suggested to differ between the sexes. Transient anatomical obstruction during fetal life has been proposed as the cause of gross VUR in males. The spontaneous resolution rate of dilating infant VUR seems to be significantly higher than in older children. A resolution of 40% of grades 4 and 5 has been reported during the first couple of years in prenatally diagnosed cases, suggesting that antireflux surgery should be postponed until after the infant year.