A posterior urethral valve is where there is tissue at the proximal end of the urethra (near the bladder outlet) that obstructs urine outflow. It only occurs in males. The obstruction to the outflow of urine creates back pressure into the bladder, ureters and up to the kidneys, causing:
- Bladder distension
- Vesicoureteral reflux (VUR) (reflux of urine from the bladder to the ureters)
- Hydroureter (swelling of the ureters)
- Hydronephrosis (swelling of the renal pelvis and calyces in the kidney)
The restriction prevents the bladder from fully emptying, increasing the risk of urinary tract infections.
Presentation
Mild cases may be asymptomatic. More significant cases present with:
- Difficulty passing urine
- Weak urinary stream
- Chronic urinary retention
- Palpable bladder
- Recurrent urinary tract infections
- Impaired kidney function
Severe cases can cause obstruction to urine outflow in the developing fetus, resulting in bilateral hydronephrosis and oligohydramnios (low amniotic fluid volume). Oligohydramnios can lead to underdeveloped fetal lungs (pulmonary hypoplasia).
Investigations
Severe cases may be detected on antenatal scans during pregnancy with oligohydramnios and hydronephrosis.
Abdominal ultrasound may show an enlarged, thickened bladder and bilateral hydronephrosis.
Micturating cystourethrogram (MCUG) shows the location of the extra urethral tissue and reflux of urine toward the kidneys.
Cystoscopy involves a camera inserted into the urethra to get a detailed view of the extra tissue. Cystoscopy can be used to ablate or remove the extra tissue.
Management
Mild cases may be observed and monitored.
A urinary catheter can bypass the valve while awaiting definitive management.
Definitive management is ablation or removal of the extra tissue during cystoscopy.
Last updated April 2025
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