This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pathology
[{'content': 'Most accurate method to detect pregnancy at 6 weeks gestation is \nSelect and explain. \nA. USG fetal cardiac activity, B. Doppler, C. Urine HCG, D. Clinical examination', 'role': 'user'}, {'content': 'Answer: A \nExplanation: "Most accurate and safest method to diagnose ble pregnancy at 6 weeks is USG for fetal cardiac activity." Ref: DaftaryFetal cardiac activity by Transvaginal USG can be picked as early as 6 weeks.Fetal cardiac activity by Transabdominal USG can be picked as early as 7 weeks.Doppler is most sensitive but not safe in early pregnancy.Doppler examination of fetal vessels in early pregnancy shouldn&;t be performed without a clinical indication. TAS can detect the fetal parameters in the following sequences:Gestational sac - 4-5 weeks of menstrual age.Fetal pole - 6th week.Fetal cardiac activity 7th week.CRL - 7th week.TVS detects the parameters 1 week earlier.(Refer: William\'s Obstetrics, 23rd edition)(Refer: Ultrasound Obstetric Gynaecology 2011; 37: 625-8)', 'role': 'assistant'}]