Early fetal megacystis between 11 and 15 weeks of gestation

The purpose of this study was to evaluate the prognostic criteria of early fetal megacystis.

A prospective, transvaginal ultrasound, cross-sectional study at 11-15 weeks of gestation at a tertiary referral fetal medicine unit.

Sixteen pregnancies out of a total of 5240 were identified with early fetal megacystis. Fetal biometry, morphology, amniotic fluid, bladder size and volume were also evaluated. The karyotype was available in 15 cases. Vesicocentesis was performed in six fetuses and three had concomitant cystoscopies.

In six fetuses, the megacystis was isolated. In the remaining ten, we detected associated hygroma (n = 5), nuchal translucency (n = 3), omphalocele (n = 1), mild pyelectasis (n = 1) and bilateral talipes (n = 1). In three cases the fetuses demonstrated renal hyperechogenicity with cysts, and in two cases oligohydramnios was found; four cases (25%) had chromosomal abnormalities; 47, XY + 13 (two cases), 47, XY + 18 and 47, XY + 21. Only one fetus from this study survived. In the remaining 13 cases, termination was proposed after counselling of the patients on the poor prognosis. The mean gestational age at termination was 15.5 +/- 2.4 weeks (range 12-20). Three fetal transabdominal cystoscopies did not allow us to view the valves; one urethral atresia was suspected, and confirmed postnatally.

We found a high rate of associated malformations, especially intestinal malformations. The systematic evaluation of the intestinal enzymes in the amniotic fluid and urine samples might be an important aid in the diagnosis of multiple malformations, such as cloacal dysgenesis.