[DISTENDED FETAL BLADDER].

Area of Science:

• Fetal medicine
• Pediatric urology
• Neonatal nephrology

Background:

• Distended fetal bladder (fetal megacystis) typically indicates lower urinary tract obstruction (LUTO), commonly posterior urethral valves (PUV) in males.
• Posterior urethral valves (PUV) are the most frequent cause of LUTO, often leading to significant fetal urinary tract abnormalities.

Purpose of the Study:

• To investigate fetal megacystis cases where primary vesicoureteral reflux (VUR) is the primary cause, not LUTO.
• To analyze the association between fetal megacystis, kidney dysplasia, renal dysfunction, and neurodevelopmental outcomes.

Main Methods:

• Retrospective case-series analysis of fetal megacystis diagnosed prenatally.
• Evaluation of postnatal outcomes, including renal function, spontaneous resolution, and neurodevelopmental assessments.
• Genetic and imaging evaluations for extra-renal malformations.

Main Results:

• Primary VUR was identified as a significant cause of fetal megacystis without oligohydramnion.
• Cases with primary VUR showed high rates of kidney dysplasia and early renal dysfunction.
• Isolated fetal megacystis without significant renal abnormalities had a benign postnatal course with spontaneous resolution.

Conclusions:

• Primary VUR is an important etiology of fetal megacystis, often associated with renal dysplasia and dysfunction.
• Isolated fetal megacystis may have a favorable prognosis, resolving spontaneously after birth.
• Associated extra-renal and neuro-cognitive abnormalities necessitate thorough genetic and imaging evaluation.