[Significance in ultrasonographic measurement of fetal limb bones (author's transl)].

Ultrasonographic measurements of fetal limb bones were studied in the cases ranged from 15 to 41 weeks of gestation. The growths of BPD, fetal femur length (FFL) and fetal humerus length (FHL) were studied, though some cases showed the difficulty in fetal biparietal diameter (BPD) measurement due to either engagement into the pelvis or rotation of fetal head. Correlation between BPD ad FFL or FHL was also evaluated. 1) Both FFL and FHL showed linear growth patterns during 16 to 40 weeks of gestation. The correlation equation; Y = 0.20X - 0.85 (R = 0.99) was obtained where X was gestational age and Y was FFL. In another equation, Y = 0.16X - 0.28 (R = 0.99) when Y was FHL. These equations showed the increment of FFL and FHL are 2.0mm and 1.6mm per a week respectively. 2) Correlation coefficients between BPD and FFL or FHL were as high as 0.97 and 0.98 respectively. 3) Comparison of in vivo ultrasonic and postnatal radiographic measurements of the femur bone of an autopsied stillbirth infant showed that the ultrasonically measured FFL corresponded to the length of ossified part of the bone. 4) Both FFL and FHL were evaluated as useful as BPD for the estimation of gestation age.