<prompt> Which of the following is the most accurate way of dating the pregnancy?Determination of uterine size on pelvic examinationQuantitative serum HCG levelCrown rump length on abdominal or vaginal ultrasoundDetermination of progesterone level along with serum HCG level  <response>: Ans. is c, i.e. Crown rump length on abdominal or vaginal ultrasoundBest method for dating of pregnancy is ultrasound in first trimester. The best parameter is Crown Rump length. 