Fetal megacystis: etiologies, management, and outcome according to the trimester

To describe the diagnostic criteria and outcome of fetal megacystis according to the gestational age at diagnosis.

A 7-year retrospective study was carried out from 2004 to 2011, including cases of megacystis referred to 2 prenatal fetal medicine units. The following data were collected and analyzed: maternal age, term at diagnosis (gestational weeks), ultrasonographic and magnetic resonance imaging data, karyotype, decision of the multidisciplinary prenatal team, fetopathology in cases of termination of pregnancy or fetal death, final diagnosis at birth after ultrasonography and voiding cystourethrography, and medical and surgical follow-up.

Of the 69 fetuses included in this study, 82.6% were males; 26 were diagnosed during the first trimester, 21 during the second, and 22 during the third. During the first trimester, the main etiologies were urethral occlusions and prune-belly syndrome with poor fetal prognosis. Nineteen pregnancies (69%) were terminated for medical reasons including the association with other malformations, poor evolution, or miscarriage. Only 4 children were born alive. The main etiologies of megacystis discovered during the second and third trimesters were vesicoureteral reflux and urethral occlusion. Twenty of 22 fetuses (91%) were born alive when the fetal megacystis was discovered after 27 weeks of gestation.

Antenatal discovery of megacystis is a complex and challenging prognostic situation. The prognosis depends on the gestational age at discovery. Megacystis is not always associated with obstruction. In a newborn with megacystis, bladder outlet obstruction has to be excluded. Optimal counseling of the involved parents requires a multidisciplinary approach.