The mother of a newborn is concerned because he has not had a wet diaper during the first 24 hours of his life. The boy is the third child for this 26-year-old mother and 29-year-old father. His siblings have no significant history. Prenatal care was appropriate and the mother says that the infant's kidneys were "a little bit swollen" on prenatal ultrasound. There was no birth trauma and no abnormalities were seen on initial examination at birth. Currently the infant appears comfortable and there is no fever. Significant findings on physical examination include a palpable mass in the suprapubic area, consistent with a distended bladder. The remainder of the genitourinary examination is normal. Which of the following is the most appropriate next step in the management of this infant?

A. Obtain a renal-bladder ultrasound
B. Order a retrograde urethrogram (RUG)
C. Perform voiding cystourethrogram (VCUG)
D. Place a urethral catheter to drain the bladder
E. Send the patient for surgery

answer is D

PUV is the most common cause of lower urinary tract obstruction in male neonates.PUV is a congenital obstruction caused by a malformation of the posterior urethra. Every child with antenatal hydronephrosis requires renal and bladder sonography performed in the immediate postnatal period. Newborn period: All male children with antenatal hydronephrosis require VCUG shortly after birth to exclude PUV. While awaiting this study, place a 5F or 8F urethral catheter to allow for bladder drainage.