This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Radiology
Gas shadow in hea and vessels are seen in 
Select and explain. 
A. IUD, B. Still bih, C. Aboion, D. Live IUGR
A: IUD
Answer: A: IUD 
Explanation: Robe sign - the presence of a gas shadow within the hea or the greater vessels, seen in cases of fetal death in utero.It is a rare sign caused by postmoem blood degeneration, usually seen 1-2 days after death; and may be seen as early as 12 hours(Ref: Diagnostic Ultrasound by Carol M. Rumack, Stephanie R. Wilson, J. William Charboneau, and Deborah Levine,4thed, page 1090)