This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Female & male reproductive system, rectum and anal canal, Subject name: Anatomy
[{'content': 'While performing culdocentesis in female patient ,needle should be most efficiently inseed through which of the following structures ? \nSelect and explain. \nA. Anterior fornix of the vagina, B. Posterior fornix of the vagina, C. Anterior wall of the rectum, D. Posterior wall of the uterine body', 'role': 'user'}, {'content': 'Answer: B \nExplanation: A needle should be inseed through the posterior fornix, just below the posterior lip of cervix while the patient is in supine position, to aspirate abnormal fluid i the cul-de-sac of Douglas(rectouterine pouch). Rectouterine excavation is not most efficiently aspirated by puncture of other structures.', 'role': 'assistant'}]