Sonographic appearance of the fetal heel ossification centers and foot length measurements provide independent markers for gestational age estimation.

The sonographic measurement of fetal foot length and the assessment of fetal heel ossification centers were conducted as an additional method for the estimation of gestational age. Such an approach is particularly desirable in cases where measurements of other biometric parameters are precluded, for example, in diseases such as anencephaly, hydrocephalus, and short limb dysplasia. A significant correlation was found between fetal foot length and gestational age (r = 0.9, p less than 0.0001) and between fetal foot length and femur length (r = 0.9, p less than 0.0001). Ossification centers of the calcaneus and talus were all present by the twenty-second week of gestation. However, their measurements discriminated between gestational ages of 18 to 22 weeks. The utilization of fetal foot length and heel ossification centers will serve as a useful adjunct in the estimation of gestational age and possibly in the diagnosis of diseases affecting the fetal foot.