Fetal age determination with selected skull biometry: a fetal cadaveric study

Determining fetal age is probably the most difficult of the four main identifiers that must be established when a fetus is found during a forensic examination. This study aimed to assess the correlation between gestational age (GA) and selected skull biometric parameters—including standard, fontanelle, and suture measurements—using linear regression analysis. A total of 104 dissected fetal skulls were used for this study. Measurements of head circumference (HC), biparietal diameter (BPD), biparietal length (BPL), bitemporal length (BTL), glabella to external occipital protuberance (G-EOP), anterior fontanelle width (AFW), anterior fontanelle length (AFL), posterior fontanelle width (PFW), posterior fontanelle length (PFL), coronal (C), sagittal (S), lambdoid (L), and metopic (M) were analyzed with GA of all fetuses. All standard measurements HC, BPD, BPL, BTL, and G-EOP showed strong positive correlations with GA (r= 0.85, 0.89, 0.9, 0.94, and 0.91, respectively). The sutural lengths C, L, and S also showed strong correlations with GA (r = 0.9, 0.83, and 0.78, respectively). The M length showed a positive correlation with GA (r = 0.68). Also, it was noted that the above parameters do not all increase at the same rate, with GA suggesting that the various parts of the fetal skull appear to grow non-linearly. All fontanelle parameters, however, showed a poor correlation with the GA (r< 0.2), and their overall sizes also varied widely with GA. The BTL, G-EOP, C, BPL, BPD, HC, L, S, and M may be independently or completely used to calculate the fetal GA from isolated skull fragments or a complete skull, respectively, with varying degrees of accuracy.