Fetal lower urinary tract obstruction: international Delphi consensus on management and core outcome set

Objectives: To reach an international expert consensus on the diagnosis, prognosis and management of fetal lower urinary tract obstruction (LUTO) by means of a Delphi procedure, and to use this to define a core outcome set (COS). Methods: A three-round Delphi procedure was conducted among an international panel of experts in fetal LUTO. The panel was provided with a list of literature-based parameters to consider for the diagnosis, prognosis, management and outcomes of LUTO. A parallel procedure was conducted with patient groups during the development of the COS. Results: A total of 168 experts were approached, of whom 99 completed the first round and 80/99 (80.8%) completed all three rounds of the study questionnaires. Consensus was reached that, in the first trimester, an objective measurement of longitudinal bladder diameter of ≥ 7 mm should be used to suspect LUTO. In the second trimester, imaging parameters suggestive of LUTO could include enlarged bladder, keyhole sign, bladder wall thickening, bilateral hydronephrosis, bilateral hydroureteronephrosis and male sex. There was 79% agreement that the current prognostic scoring systems in the literature should not be used clinically. However, experts agreed on the value of amniotic fluid volume (at < 24 weeks) to predict survival and that the value of fetal intervention is to improve the chance of neonatal survival. Experts endorsed sonographic parameters suggestive of renal dysplasia, at least one vesicocentesis, and renal biochemistry for prognosis and counseling, but these items did not reach a consensus for determining candidacy for fetal intervention. On the other hand, imaging parameters suggestive of LUTO, absence of life-limiting structural or genetic anomalies, gestational age of ≥ 16 weeks and oligohydramnios (defined as deepest vertical pocket < 2 cm) should be used as candidacy criteria for fetal intervention based on expert consensus. If bladder refill was evaluated, it should be assessed subjectively. Vesicoamniotic shunt should be the first line of fetal intervention. In the presence of suspected fetal renal failure, serial amnioinfusion should be offered only as an experimental procedure under research protocols. A COS for future LUTO studies was agreed upon. Conclusion: International consensus on the diagnosis, prognosis and management of fetal LUTO, as well as the COS, should inform clinical care and research to optimize perinatal outcomes.