<s>[INST] My last period was on14th dec 2010. I found out I was pregnant on the 17th Jan 2010. Due to some abdominal pain I was reffered to do a internal ultra sound. The ultra sound showed gastational sac measuring 1.6 mm, ChatDoctor levels 420. On 4th feb 2011 gastational sac measured at 6.5 mm with a yolk sac but no baby. I was told that I was probably having a miscariage as the sac was only measuring at four weeks instead of seven and my ChatDoctor levels were 2000. Is it possible that this could still be a viable pregnancy? [/INST] Hello, I have gone through your query and here are the answers:1. The period of gestation is determined either calculating from the last menstrual period if the cycles are regular or from an early sonogram. 2. If there is no evidence of a fetal pole, the sonogram should be repeated, preferably in the trans-vaginal route, after a week. Sometimes, due to miscalculation of the dates, errors can happen, but, the size of the gestation sac is confirmatory. 3. This should be coupled with serial titles of serum beta-ChatDoctor. Doubling titles every 2-3 days are observed if the pregnancy is progressing well. With all these done, if it is concluded that there is no progress, then it is a missed abortion. Further management should be planned accordingly. Hope this helps. </s>