Postnatal urinary tract dilatation classification: improvement of the accuracy in predicting kidney injury

Urinary tract dilation classification system for predicting surgical management and urinary tract infection in neonates and young infants: a systematic review and meta-analysis

BACKGROUND

The urinary tract dilation classification system has recently been developed to ensure a unified approach to describe urinary tract dilation in neonates and young infants. However, the predictive value of this system for surgical intervention or urinary tract infection (UTI) has not yet been evaluated in a meta-analysis.

OBJECTIVE

This systematic review and meta-analysis aimed to evaluate the utility of a postnatal urinary tract dilation classification system for predicting surgical management or a UTI occurrence.

MATERIALS AND METHODS

As the urinary tract dilation classification system was introduced in 2014, we searched Embase and PubMed databases for studies published between January 2014 and December 2022. Original articles that reported surgical interventions or UTI episodes according to postnatal urinary tract dilation grades were included. The pooled odds ratio (OR) was calculated, using either the fixed-effects or random-effects model, given the lower urinary tract dilation grades as the base category. The quality of the included studies was evaluated using the Newcastle-Ottawa scale.

RESULTS

Of the 285 articles reviewed, eight (comprising 2,165 children) were included in the analysis. The studies were of medium-to-high quality. Pooled analysis demonstrated that urinary tract dilation P3 (combined OR, 21.41; 95% confidence interval [CI], 15.72-29.17) and urinary tract dilation P2-P3 (combined OR, 65.17; 95% CI, 33.08-128.38) were associated with surgical intervention. The urinary tract dilation P3 (combined OR, 2.11; 95% CI, 1.56-2.85) and urinary tract dilation P2-P3 (combined OR, 3.36; 95% CI, 2.43-4.63) were associated with UTI episodes.

CONCLUSION

The postnatal urinary tract dilation classification system is useful for predicting the need for surgical management and UTI episodes in infants with hydronephrosis.

Antenatally detected urinary tract dilatation: long-term outcome

This review provides updated knowledge on the long-term outcomes among children with antenatally diagnosed urinary tract dilatation (UTD), previously often referred to as antenatal hydronephrosis. Different definitions of UTD exist, which makes comparison between studies and generalized conclusions difficult. Roughly, one-third of antenatally diagnosed UTD, defined as a renal pelvis anterior posterior diameter (APD) of ≥ 4 mm in the second trimester and/or ≥ 7 mm in the third trimester, will resolve before birth, another third will resolve within the first years of life, and in the remaining cases, UTD will persist or a congenital abnormality (CAKUT) will be diagnosed postnatally. The risk of a postnatal CAKUT diagnosis increases with the degree of prenatal and postnatal dilatation, except for vesicoureteral reflux (VUR), which cannot be predicted from the degree of UTD. Urinary tract infections (UTIs) occur in 7-14% of children with UTD during the first years of life. The risk of UTI is higher in children with traditional risk factors for UTI, such as dilated VUR, hydroureteronephrosis, female gender, and intact foreskin. Continuous antibiotic prophylaxis may be considered in selected patients during the first years of life. In long-term follow-ups, permanent kidney damage is diagnosed in approximately 40% of children with moderate or severe UTD, but hypertension, proteinuria, and/or reduced eGFR are uncommon (0-5%). In children with mild UTD, the long-term outcome is excellent, and these children should not be subjected to unnecessary examinations and/or follow-up.