Background: Prenatal hydronephrosis is common and may vary in size. Although mostly unproblematic, it may be a sign of urinary tract obstruction of differing severity.
Case diagnosis/treatment: We present a boy with prenatally detected bilateral giant hydronephrosis. A prenatal ultrasound showed the whole abdominal cavity of the fetus filled with urine. Kidney parenchyma could not be seen. The boy was born at 34 + 1 weeks' gestation. After delivery, he showed a severely distended abdomen. Insertion of a nasogastric tube was not possible, and he had to be intubated due to respiratory distress. A bilateral percutaneous nephrostomy was performed immediately. After a few hours, he could be stabilized and extubated. An ultrasound on the following day showed two kidney units with normal kidney parenchyma of normal size. The initially slightly elevated serum creatinine level normalized within one week. An antegrade pyelography via the nephrostomy tubes showed bilateral ureteropelvic junction obstruction.
Conclusion: Severe bilateral hydronephrosis may be associated with good outcome and well-preserved kidney function. Prenatal counseling should be done carefully, with discussion of different treatment possibilities and without definitive prediction of outcome.
Keywords: CAKUT (congenital anomalies of the kidney and urinary tract); giant hydronephrosis; newborn; prenatal; ureteropelvic junction obstruction.