Antenatal ultrasound to predict postnatal renal function in congenital lower urinary tract obstruction: systematic review of test accuracy.

Background Congenital urinary tract obstruction can lead to perinatal mortality and morbidity. Assessing antenatal ultrasound features may help identify fetuses likely to suffer complications. Objective To evaluate the accuracy of antenatal ultrasound in the prediction of postnatal renal function in cases of congenital lower urinary tract obstruction (LUTO). Search strategy We conducted electronic searches in MEDLINE, EMBASE, the Cochrane Library, MEDION, SIGLE, SCISEARCH Index of scientific and technical proceedings, National Research Register (database inception - 2008) and Medical Conferences register and searched reference lists. Selection criteria Two reviewers independently selected articles in which the accuracy of fetal ultrasound features were evaluated to predict postnatal renal function with no language restrictions. Data collection and analysis Data were extracted on study characteristics, quality and results to construct 2 x 2 tables. Likelihood ratios for positive (LR+) and negative (LR-) test results, sensitivity and specificity were generated for the different ultrasound parameters and reference standards. Main results Thirteen articles that met the selection criteria, including 215 women and 33 2 x 2 tables. Meta-analysis was performed using clinically similar subgroups to minimise clinical heterogeneity. The ultrasound parameter that showed the best predictive value for postnatal renal function in survivors was renal cortical appearance, sensitivity 0.57 (95% CI 0.37-0.76) and specificity 0.84 (95% CI 0.71-0.94), area under the curve 0.78. Conclusion Measurement of amniotic fluid volume and the appearance of the renal cortex at diagnosis of LUTO show promising predictive accuracy for poor postnatal renal function.