P07.06: Diagnosis of patent urachus in first trimester: a case report

Abstract

Patent urachus results when there is a persistence of an allantois remnant, which normally undergoes atresia during embryological development. It is a rare umbilical anomaly, which is poorly detected prenatally and frequently confounded with pseudo bladder extrophy, megacystis or omphalocele. A 28-year-old woman, primigravida, was referred to our maternal-fetal medicine center at 12 weeks of gestation after diagnosis of a megabladder. Subsequent 2D and 3D ultrasound examination revealed a large hypoechogenic cyst communicating with the vertex of the relative small bladder. Serial ultrasound scans every two weeks showed the cyst to increase up to 45 mm. Amniocentesis at 16 weeks demonstrated a normal male karyotype. Termination of pregnancy occurred at 18 weeks because of associated progressive bilateral hydronefrosis. Subsequent autopsy confirmed the prenatal diagnosis of patent urachus cyst and described hydronefrosis and microcolon. Few cases of urachus cyst diagnosed prenatally are reported in the literature, but none were associated with progressive dilated uropathy. Although patent urachus is not life threatening and has good prognosis, concomitant fetal structural anomalies could change a perinatal result. Our case illustrated the possibility and efficiency in prenatal diagnosis of 2D/3D ultrasound examination. Supported by the grant MZOFNM2005 and CZ.2.16/3.1.00/24022.