Isolated congenital megacystis with spontaneous resolution: a case report.

The patient was a male infant with an antenatal diagnosis of huge intraabdominal mass. Prenatal ultrasound at 35 weeks gestation revealed a markedly enlarged cystic mass in the lower abdomen. After birth at 38 weeks, the infant was allowed to void spontaneously and passed meconium. Ultrasonography showed an enlarged bladder with wall thickness of 2.9 mm and no hydronephrosis. Voiding cystourethrograms showed no evidence of vesicoureteral reflex and posterior urethral valve. The post-void residuals were 15 mL at 11 days of life, 5 mL at 1 month and 0 mL at 5 months. Over 10 years' follow-up, the patient remains completely well without any urinary or gastrointestinal symptoms. In sporadic isolated congenital megacystis, which is not so rare in fetuses but is quite rare in neonates, gastrointestinal symptoms may be masked in the neonatal period; however, the present patient has never presented any symptoms.