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: Gynaecology & Obstetrics
[{'content': 'Most common site of ectopic pregnancy in fallopian tube: March 2005 \nSelect and explain. \nA. Infundibulum, B. Ampulla, C. Isthmus, D. Interstitium', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B: Ampulla The vast majority of ectopic pregnancies implant in the Fallopian tube. Pregnancies can grow in the infundibulum (18% of all ectopics), the ampullary section (55%), the isthmus (25%), and the interstitial pa of the tube (20%). Moality of a tubal pregnancy at the isthmus or within the uterus (interstitial pregnancy) is higher as there is increased vascularity that may result more likely in sudden major internal hemorrhage.', 'role': 'assistant'}]