Estimation of Gestational age of the fetus by ultrasonographic measurement of the thickness of placenta

AIM OF THE STUDY: To evaluate the placental thickness as an ultrasonographic parameter for estimating the gestational age of fetus. MATERIALS AND METHODS: Source of Data: Uncomplicated antenatal cases from antenatal clinic at the Department of Obstetrics and gynaecology, RSRM Hospital, Government Stanley Medical College, Chennai are included. Along with fetal biometry (BPD, FL, AC, HC) placental thickness was measured and the labor outcomes of those women were followed. Study Design: Period of study: 1 year (June 2013 – June 2014). Design of study: cross sectional study. Sample size: 242 cases, 42 cases did not come for delivery to our Hospital. The dissertation studies the placental thickness by ultrasonography at the level of umbilical cord insertion as a parameter for determining the gestational age of fetus. Inclusion criteria: 1. Antenatal women of gestational age 20-40 weeks. 2. Patients with known dates of last menstrual period. 3. Singleton pregnancies with no fetal or congenital anomalies. 4. No medical or obstetrical complications. 5. H/o regular menstruation. Exclusion criteria: 1. Patients with P.I.H., Diabetes Mellitus, Intrauterine growth restriction, hydrops fetalis, congenital malformation, twins, polyhydramnios. 2. Placental morphological variations. 3. Poor sonographic visualization of placenta due maternal obesity and other causes 4. Oligo hydramnios 5. Variation in umbilical cord insertion – battledore placenta, velamentous cord insertion. RESULT AND OBSERVATION: In our study 200 uncomplicated antenatal cases from 20 weeks to 40 weeks of gestation were included along with others fetal biometry placental thickness was measured and the labor outcome of those women was followed. The results were analysed with respect to maternal age, parity, placental thickness, birth weight and gestational age at birth. The mean values of placental thickness & its standard deviation were calculated for gestational age from 20 – 40 week. Using pearson’s, correlation between gestational age and Placental thickness analysed. Diagnostic ultrasound is a non invasive, safe and useful investigative method sought by the obstetrician to clear different dilemmas in obstetrics. It is an easy & simple method and free from risk to the mother and unborn fetus. In our study, patients with known LMP were taken & placental thickness measurements were recorded & maturities of the fetus were assessed after birth. Our study shows that the parity, maternal age shows no significant bearing in the assessment of placental thickness and its correlation to gestational age. In our study placental thickness increases with advancing gestation matching from 20 to 35 week. The present study has shown a significant correlation between the placental thickness and gestational age particularly in late 2nd and 3rd trimester. To conclude, one can say the measurement of placental thickness is an important additional parameter for estimation of fetal age along with other fetal biometry. It is useful in cases where the exact duration of pregnancy is not known Between 20 and 35 weeks, the placental thickness almost matches with gestational age. Placental thickness can be used as a reliable parameter in late 2nd & 3rd trimester for calculating GA. CONCLUSION: To conclude, one can say the measurement of placental thickness is an important parameter for estimation of fetal age. It is helpful in cases where the exact duration of pregnancy is not known (between 20 and 35 weeks) where the placental thickness almost matches with gestational age