Sonographic Placental Thickness Measurement: A Trustworthy Saviour for Foetal Age Estimation in Uncomplicated Pregnancy

Abstract

Introduction: Placenta is a foeto-maternal organ playing a crucial role in endocrine, immunological, excretory, respiratory, and nutritional functions for the foetus. Gestational age estimation is usually based on the last menstrual period and ultrasonography. Many females having irregular menstruation present with unreliable last menstrual period and hence ultrasonography comes into play for correctly estimating the gestation. Various sonologically derived foetal parameters used for gestational age estimation are Crown Rump Length (CRL), Biparietal Diameter (BPD), Head Circumference (HC), and Abdominal Circumference (AC). The placental thickness measurement shows a direct correlation with the gestational age of the foetus till certain weeks of pregnancy, therefore could be utilised as a new and simple parameter in scenarios like term pregnancy where other parameters are unreliable. Aim: To study the relationship between sonographic placental thickness measurement and gestational age of the foetus and also correlating other biometric parameters i.e., BPD, AC, femur length with placental thickness. Materials and Methods: The present study was a crosssectional study conducted in the Department of Radiodiagnosis, in collaboration with the Department of Obstetrics and Gynaecology, Rohilkhand Medical College and Hospital, Bareilly, Uttar Pradesh, India. Sample size constituted of 200 normal antenatal women in whom the placental thickness for various gestational age and correlation between placental thickness measurement with the gestational age of the foetus was done. Analysis of the relationship between placental thickness and other foetal parameters like BPD, femur length and AC was also assessed using Pearson correlation coefficient. Results: Placental thickness measurements for gestational age 11-39 weeks were calculated; it gradually increased from 11.29 mm (mean) at 11 weeks to 35 millimeters (mm) (mean) at 39 weeks of gestation. Correlation coefficient was 0.9685 and p-value <0.01. Also, there was a significant positive correlation of placental thickness with other foetal biometry parameters like BPD, femur length and AC (p<0.001). Conclusion: The measurement of placental thickness can become a key parameter for estimation of foetal age especially in cases where the exact duration of pregnancy is not known. It can also facilitate the detection of abnormal placental thickness associated with maternal and foetal complications in the early stages.

Keywords

• foetal biometry
• last menstruation period
• gestation
• ultrasonography