This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gastrointestinal tract, Subject name: Pediatrics
X-ray detect congenital anorectal malformation at 
Select and explain. 
A. Immediately after bih, B. 24-48 hours, C. 48-72 hours, D. After 72 hours
B: 24-48 hours
Answer: B: 24-48 hours 
Explanation: ANORECTAL ANOMALIES Anatomically classified as high,intermediate or low An Xray film of the abdomen is obtained 12-24 hours after bih,with the baby being kept in an inveed position. a lateral picture of the pelvis obtained to define whether the rectal pouch is above or below the line drawn from the pubis to coccyx. Anovestibular fistula in females and anorectal agenesis with retroprostatic urethral fistula are common in male infants Ref : ESSENTIAL PEDIATRICS,O.P.GHAI,PG NO:152,7th edition