urethral obstruction (disease) fetal lower urinary tract obstruction urethral obstruction sequence EUOS GARD:0005428 MESH:C536477 MONDO:0043207 SCTID:18241005 UMLS:C0265363 early urethral obstruction sequence renal dysplasia or hydronephrosis, oligohydramnios and subsequent lung hypoplasia due to urethral obstruction