Functional Lower Urinary Tract Obstruction Mimicking Posterior Urethral Valves; A Report of Two Children
Rohit Tejwani, MD, Ashley W. Johnston, MD, J Todd Purves, MD, PhD, Jonathan C. Routh, MD, MPH, John S. Wiener, MD
Division of Urology, Department of Surgery, Duke University School of Medicine, Durham, NC
Congenital lower urinary tract obstruction (LUTO) is a significant cause of pediatric renal dysfunction. Fetal sonographic findings of posterior urethral dilation, megacystis, and hydroureteronephrosis suggest LUTO; neonatal voiding cystourethrogram (VCUG) demonstrating posterior urethral dilation should further raise suspicion for anatomic obstruction (e.g. posterior urethral valves (PUV)). We present cases of suspected PUV during fetal evaluation that demonstrated no anatomic obstruction on postnatal work-up.
Fetal ultrasound at 12 weeks demonstrated bladder dilation (4.4 x 3.6 x 3.2cm), bilateral hydroureteronephrosis, and positive keyhole sign. Born at 39 weeks, he voided on first day-of-life (DOL). VCUG on DOL3 demonstrated posterior urethral dilation. On DOL6, cystourethroscopy revealed a non-obstructive Cobb's Collar, absent PUV, and normal bladder. Subsequently, he experienced increasing inter-void intervals until retention at 18 months. Urodynamics demonstrated a capacious (800mL), hypocontractile bladder and hypertonic urethra. At 19 months he underwent vesicostomy creation, with eventual conversion to a Mitrofanoff channel.
Fetal ultrasound at 19 weeks revealed megacystis and bilateral hydronephrosis. Follow-up fetal ultrasound showed hydroureter as well. After delivery at 40 weeks, voided on DOL1. VCUG (DOL3) demonstrated prostatic through proximal-bulbous urethral dilation; cystourethroscopy on DOL6 revealed posterior urethral dilation, bladder trabeculae, and no valves. After admission for febrile UTI and impaired renal function on DOL14, repeat cystourethroscopy again showed no valves and presence of a circumferentially thickened sphincter. A cutaneous vesicostomy was then created.
These represent a poorly-described etiology of congenital, functional LUTO. Despite absence of anatomic obstruction, both patients ultimately experienced worsening bladder and renal dysfunction prompting need for cutaneous diversion.
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