ABSTRACT
Ultrasonographic measurement of foetal biparietal diameter [BPD] and femur length [FL] was done on 88 pregnant women, with sure dates between 1642 weeks' gestation. A real lime scanner with a 3.5 mHz transducer frequency was used. All cases had a single examination and all had uncomplicated pregnancy. A good correlation was found [r = 0.8506 and p < 0.025] between menstrual gestation age and that predicted from the BPD. An even better correlation [r = 0.8917 and p < 0.025] was found when we predicted fetal gestational age from FL. Gestational ages predicted from femur length were particularly more accurate than those predicted from BPD after 34 weeks' gestation. A linear relationship between the growth of FL and BPD after 16 weeks' gestation is described. FL/BPD ratio is almost constant over this age range. The ratio was found to be 0.81 +/- 0.13 [mean +/- 2 SD] in this study. This ratio can practically be used as a quality control check on femur length and BPD measarements. It can also help early diagnosis of short-limbed dwarfism, hydrocephalus and microcephaly