This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General obstetrics, Subject name: Gynaecology & Obstetrics
[{'content': 'Pseudogestational sac is seen in \nSelect and explain. \nA. Missed aboion, B. Threatened aboion, C. Inevitable aboion, D. Ectopic pregnancy', 'role': 'user'}, {'content': 'Answer: D \nExplanation: The gestational sac --an anechoic fluid collection that represents the exocoelomic cavity--may be seen by 4.5 weeks.A caveat is that a gestational sac may appear similar to other intrauterine fluid accumulations--the so-called pseudogestational sac. This pseudosac may be seen with ectopic pregnancy and is easier to exclude once a yolk sac is seen. Typically, the yolk sac is visible by 5.5 weeks and with a mean gestational-sac diameter of 10 mm. Thus, the diagnosis of a uterine pregnancy should be made cautiously if the yolk sac is not yet seen.Ref: William&;s Obstetrics; 24th edition; chapter 19', 'role': 'assistant'}]