This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Radiology
Inveogram to be done in a new born : 
Select and explain. 
A. Immediately, B. After 2 hours, C. After 4 hours, D. After 6 hours
D: After 6 hours
Answer: D: After 6 hours 
Explanation: D i.e. After 6 hours Inveogram is done to detect imperforate anusQ. It is done after six hours of bihQ in infant as sufficient air may have collected in large intestine to cast a x Ray Shadow. If the distance between highest level of gas in rectum & metal bougie inseed into the blind anal canal is > 2.5 cmQ; the abnormality is high. In high lesion, the presence of proteus or pseudomonas in urineQ is indicative of fistula. I.V. Urogram & gas in bladder also indicate, fistula, but with definite radiation risk.