This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Obstetrical Ultrasonography in the First Trimester, Subject name: Radiology
Gas shadow in heart and great vessels appears in- 
Select and explain. 
A. IUD, B. Abortion, C. Still birth, D. None
A: IUD
Answer: A: IUD 
Explanation: Ans. is 'a' i.e., IUD o In intrauterine death (IUD), there is gas in great vessels and chambers of heart - Robert's Sign.