<prompt> Earliest diagnosis of pregnancy can be established safely by:AIIMS May 2015, November 2013USG for fetal cardiac activityFetal cardiac Doppler studyhCG levelsMRI pelvis  <response>: Ans. C. Ref: Williams Obstetrics 24e p196; Ultrasound Obstet Gynecol 2011; 37:625-628: Dutta 768 By radio immunoassay detected in maternal serum or urine as early as 8-9 days following ovulationQ. USG for fetal cardiac activity: At 6 weeks it is routine to detect fetal cardiac activity by ultrasound and Doppler is not indicated. Doppler is most sensitive but not safe in early pregnancy Doppler examination of fetal vessels in early pregnancy should not be performed without a clinical indication- Ultrasound Obstet Gynecol 2011; 37:625-628 Week 6 - Gestational Age Fetal age 4 weeks 5 12 to 6 12 weeks is usually a very good time to detect either a fetal pole or even a fetal heart-beat by vaginal ultrasound. The fetal pole is the first visible sign of a developing embryo. The fetal pole now allows for crown to rump measurements CRL to be taken, so that pregnancy dating can be a bit more accurate. The fetal pole may be seen at a crown-rump length CRL of 2-4 mm, and the heartbeat may be seen as a regular flutter when the CRL has reached 5 mm. If a vaginal ultrasound is done and no fetal pole or cardiac activity is seen, another ultrasound scan should be done in 3-7 days. Human Chorionic Gonadotrophin hCG is a glycoprotein It consists of a hormone non-specific a and a hormone specific P subunitQ. It is chemically and functionally similar to pituitary luteinizing hormone The a subunit is biochemically similar to LH, FSH and TSH whereas B subunit is relatively unique to hCG Have highest carbohydrate content 30 of any human hormone Functions of Human Chorionic Gonadotrophin Rescue and maintenance of corpus luteum till 6 weeks of pregnancyQ Stimulates both adrenal and placental steroidogenesisQ Stimulates maternal thyroidQ because of its thyrotrophic activity Immunosuppressive activityQ which may inhibit the matemal process of immunorejection of the fetus as the homograft Stimulates Leydig cells of the male fetusQ to produce testosterone in conjunction with fetal pituitary gonadotrophins Levels of hCG: Production by syncytiotrophoblastQ Half life24 hours. Doubling time48 hours 2 daysQ By radio immunoassay detected in maternal serum or urine as early as 8-9 days following ovulationQ. Maximum blood and urine level 100-200 lUml between 60-70 days of pregnancyQ Disappears from circulation within 2 weeks following deliveryQ High levels of hCG is detected in Multiple pregnancyQ Hydatidiform mole or ChoriocarcinomaQ Downs syndromeQ Erythroblastosis fetalis resulting from maternal D-Ag isoimmunization hCG is decreased in ectopic pregnancy and impending spontaneous abortion. 