OC03.01: Fetal lower urinary tract obstruction: international Delphi consensus on management and core outcomes set

To reach an international expert consensus on the diagnosis, prognosis, management and core outcome set (COS) of fetal Lower Urinary Tract Obstruction (LUTO). A three-round Delphi procedure was conducted among an international panel of LUTO experts. The panel was provided with a list of literature review generated parameters for the diagnosis, prognosis, management, and outcomes. A parallel procedure was conducted along with patient groups during the development of COS. A total of 160 experts were approached, of whom 99 completed the first round and 80 (81%) completed all three rounds. In the first trimester, an objective measurement of longitudinal bladder diameter (with ≥7mm being abnormal) should be used to suspect LUTO. In the second trimester, imaging parameters of LUTO could include: an enlarged bladder, a keyhole sign, bladder wall thickening, bilateral hydro (uretero) nephrosis, and male sex. Experts agreed on the value of amniotic fluid volume (<24 weeks) to predict survival and that the value of fetal intervention is to improve neonatal survival. While experts endorsed the role of sonographic parameters of renal dysplasia, at least one vesicocentesis, and urine biochemistry for prognosis and counselling, these items did not reach consensus for determining fetal intervention candidacy. On the other hand, imaging parameters suggestive of LUTO, absence of life-limiting structural or genetic anomalies, gestational age at or beyond 16 weeks, and oligohydramnios defined as deepest vertical pocket (DVP) <2cm should be used as candidacy criteria for fetal intervention. Vesicoamniotic shunt should be the first line fetal intervention. In the presence of suspected fetal renal failure, serial amnioinfusion should only be offered as an experimental procedure under research protocols. International consensus on the diagnosis, prognosis and management of fetal LUTO, as well as COS should inform clinical care and research to optimise perinatal outcomes.