This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Kidney, Subject name: Pediatrics
Most common cause of acute retention of urine in a child of 2 years age: 
Select and explain. 
A. Posterior urethral valve, B. Duplication of renal pelvis, C. Meatal ulceration with scabbing, D. Urethral stones
C: Meatal ulceration with scabbing
Answer: C: Meatal ulceration with scabbing 
Explanation: c. Meatal ulceration with scabbing(Ref: Nelson's 20/e p 2562-2567, Ghai 8/e p 485-486)Meatal ulceration with scabbing can cause acute retention of urine.Dont get confused by option 'a'- Though posterior urethral valve is the most common cause of obstructive uropathy in children, it does not cause acute retention.Posterior urethral valve usually presents with chronic obstructive symptoms like weak urinary stream, distended bladder, uremia or sepsis caused by infection in the obstructed urinary tract.Urethral stone may cause obstruction, but the most common presentation is hematuria with or without pain.