ULTRASONOGRAPHIC MEASUREMENT OF PLACENTAL THICKNESS AND ITS CORRELATION WITH GESTATIONAL AGE – A CROSS-SECTIONAL ULTRASONOGRAPHIC STUDY.

Introduction: Study of placental morphology is a part of the overall assessment of intrauterine environment. Placental growth can be estimated by either measuring the thickness or estimating its volume. Placental thickness is directly related to the gestational age of the foetus during certain period of pregnancy. Thus placental thickness can be used to determine the gestational age. Objectives: The purpose of the present study was to determine the normal range of placental thickness in study population in first and second trimesters of pregnancy and its correlation with gestational age of the foetus. Methods: 153 cases were recruited for the study who came for routine antenatal check-up to Department of Radiology in collaboration with Department of Obstetrics and Gynaecology, tertiary care service hospital. Subjects who had any obstetrical, gynaecological, medical and surgical illnesses were excluded. Placental thickness was measured at the level of umbilical cord insertion. Result: placental thickness ranged from 11.4 mm to 28.2 mm with majority having placental thickness in the range 16 to 28 mm. A strong correlation between gestational age and placental thickness was observed (r=0.9994 for biometric GA and r=0.9673 for LMP based GA). Discussion: PT has a linear relationship with GA. It can be therefore concluded that PT can be used as a predictor of the GA in women with unreliable or unknown LMP. The substitution of any abnormal parameter like BPD in hydrocephalus with PT in sonography for GA estimation is also suggested.