This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous (Gynae), Subject name: Gynaecology & Obstetrics
[{'content': 'Earliest ectopic to undergo rupture is: \nSelect and explain. \nA. Interstitial, B. Isthmic, C. Ainpullary, D. Ovarian', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans: b (Isthmic) Ref: D 6th ed, p. 181Ibbal ruptureMost common in isthmic regionIsthmic rupture - 6-8 wksAmpullary rupture -8-12 wksInterstitial rupture - 16 wksEctopic pregnancyCommonest site - AmpullaCommonest cause - PID (Salpingitis) due to STDCommonest mode of termination of tubal pregnancy -Tubal abortionArias-Stella reaction - typical adenomatous change of endometrial glands seen in ectopic pregnancy.', 'role': 'assistant'}]