Dilatation of the bladder Fetal megacystis 2011-01-18T10:43:58Z Foetal megacystis Fetal megacystis is an abnormally enlarged bladder identified at any gestational age. HP:0010956 Abnormal enlargement of the fetal bladder can be detected by prenatal ultrasound by fourteen weeks of gestation. In some cases, dilatation of the fetal bladder is transient and resolves without sequelae, and in other cases it is the earliest manifestation of bladder outlet obstruction. UMLS:C2931117