Most accurate and safest method to diagnose viable pregnancy at 6 weeks:(AIIMS May 2015, Nov 20/3)
Ans. b. USG for fetal cardiac activity (Ref: Ultrasound Obstet Gynecol 2011; 37:625-628; Dutta 6/e p68)Most accurate and safest method to diagnose viable pregnancy at 6 weeks is USG for fetal cardiac activity.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: 37:625-628Week 6 - Gestational Age (Fetal age 4 weeks)* 5 1/2 to 6 1/2 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 2-4mm. and the heartbeat may be seen as a regular flutter when the CRL has reached 5mm.* 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 b subunitQ.* It is chemically and functionally similar to pituitary leutenising 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 hormoneFunctions:1 Rescue and maintenance of corpus luteum till 6 weeks of pregnancyQ (major biological function)2 Stimulates Leydig cells of the male fetusQ to produce testosterone in conjunction with fetal pituitary gonadotrophins3 Immunosuppressive activityQ which may inhibit the maternal process of immunorejection of the fetus as the homograft4 Stimulates both adrenal and placental steroidogenesisQ5 Stimulates maternal thyroidQ because of its thyrotrophic activityLevels of hCG:* Production by syncytiotrophoblastQ* Half life = 24 hours, Doubling time = 48 hours (2 days)Q* By radio immunoassay detected in maternal serum or urine as early as 8-9 days following ovulationQ* Maximum blood and urine level 100-200 IU/ml between 60-70 days of pregnancyQ* Disappears from circulation within 2 weeks following deliveryQHigh levels of hCG is detected in:1 Multiple pregnancyQ2 Hydatiform mole or ChoriocarcinomaQ3 Down's syndromeQ4 Erythroblastosis fetalisQ resulting from maternal D-Ag isoimmunisation hCG is decreased in Ectopic pregnancy and Impending spontaneous abortion.
Doppler assessment of fetal cardiac activity
USG for fetal cardiac activity
Urinary Beta-hCG determination
Per vaginal examination of uterine size corresponding to 6 weeks gestation
Diagnosis of Pregnancy