<s>[INST] context: Poor urinary stream in 3 years old boy suggests urinary tract obstruction (usually intravesical) and the most common cause of obstructive uropathy in a male child is posterior urethral valve.
Posterior urethral valve

These are symmetrical folds of urothelium extending distally from prostatic urethra to external urinary sphincter.
It most commonly lies just distal to the verumontanum or at the verumontanum*
It occurs only in males.
It behaves as flap valves so, although urine does not flow normally a urethral catheter can be passed without difficulty.
Sometimes, the valves are incomplete and the patient remains without symptoms until adolescence or adulthood.
Approximately 30% of patients experience end stage renal disease
Vesicoureteral reflux occurs in 50% of patients.

Diagnosis is made by

voiding cystourethrogram* &
endoscopy


Both of these investigations clearly depict the site of obstruction.
The diagnosis can be established prenatally by ultrasound.*

Management

First, a small polyethene feeding tube is inserted in the bladder and left for several days. Then further management is done according to serum creatinine level.


with normal serum creatinine → transurethral ablation of the valve leaflets. *
With increased serum creatinine and the worsening of condition → vesicostomy to bypass the obstruction and when normal creatinine levels are achieved, transurethral ablation is done. [/INST] question: A three years old boy presents with the poor urinary stream. Most likely cause is - | options: A: Stricture urethra B: Neurogenic bladder C: Urethral calculus D: Posterior urethral valve | answer: D </s>