Sonographic evaluation of the Amniotic Fluid Index in normal singleton pregnancies in a Nigerian population.

Abstract

Estimation of amniotic fluid volume is an integral part of the routine obstetric ultrasound scan and the amniotic fluid index (AFI) is one of the methods for doing this. Reduction or excessive production of amniotic fluid during pregnancy is also a strong predictor of possible associated congenital fetal anomaly. This study was to assess the AFI in Nigerian women and correlate same with their gestational age. It is a prospective cross sectional study of 300 scanned singleton pregnancies between 15-42 gestational ages. Their amniotic fluid indices were determined and correlated with their gestational age. A statistical analysis of data was done using the SPSS version 16, Chicago, Illinois. The study population mean AFI was 12.91±4.82cm, ranging from 4.17 - 22.05cm and a median of 12.56; the 5 th and 95 th percentile being 5.81 and 21.95 respectively. The mean AFI for preterm and term gestations were 12.70±5.02cm and 14.07±3.34cm respectively. There was no statistically significant difference between the mean AFI of the total study population and that of preterm and term gestations. The peak mean AFI value occurred at 28 weeks gestational age, with no bias in the distribution of amniotic fluid in the four quadrants of the uterus. Apart from establishing the normal AFI values in this environment, this study also showed that there was a weak positive correlation between gestational age and AFI, with no statistically significant difference in AFI of preterm and term gestations.