Ultrasonographic assessment of foetal age using biparietal diameter and femoral length

ABSTRACT

The foetuses of 886 pregnant females who were sure of their date of last menstrual period [LMP], had regular previous menstrual cycles and had no chronic/systemic illness, were studied. For biparietal diameter [BPD] "outer to inner" and for femoral length [FL] "metaphysis to metaphysis" approach was used. Only those foetuses were included in the study who had a cephalic index between 75 and 85 and an FL/BPD ratio between 70 and 86. A number of 591 patients were followed up to delivery. Out of these, 505 patients met the criterion of spontaneous delivery within 2 weeks of the expected date of delivery counted from LMP. Results form these patients were plotted in graph form and a scattergram prepared. After necessary averaging, optimum smoothed curves and then separate tables were prepared. An average BPD of 9.3 cm and an average FL of 7.2 cm were noted against a 40 weeks gestation. On comparing with a number of foreign studies it was found that measurements carried out at Tokyo University [1988] were closest to those of this study