Bladder retention of urine as a result of continuous intravenous infusion of fentanyl: 2 case reports.

Sedation has been commonly used in the neonate to decrease the stress and pain from the noxious stimuli and invasive procedures in the neonatal intensive care unit, as well as to facilitate synchrony between ventilator and spontaneous breaths. Fentanyl, an opioid analgesic, is frequently used in the neonatal intensive care unit setting for these very purposes. Various reported side effects of fentanyl administration include chest wall rigidity, hypotension, respiratory depression, and bradycardia. Here, 2 cases of urinary bladder retention leading to renal pelvocalyceal dilatation mimicking hydronephrosis as a result of continuous infusion of fentanyl are reported.