Table 2. Measurement statistics, giving the range (min., max.), mean and standard variation (SD).
| Fetal | Adult‡ | Difference of means§ | |||||
|---|---|---|---|---|---|---|---|
| Measure | Min. | Max. | Mean | SD | Mean | SD | |
| BPD (mm) | 11 | 77 | 40.4 | 18.5 | – | – | – |
| Age (weeks) | 9.4 | 29.2 | 17.8 | 5.3 | – | – | – |
| Size (mm) | |||||||
| IEL | 3.7 | 17.5 | 11.78 | 3.92 | – | – | – |
| ASC-R | 0.8 | 3.8 | 2.41 | 0.83 | 3.2 | 0.24 | – |
| PSC-R | 0.7 | 3.6 | 2.24 | 0.85 | 3.1 | 0.30 | – |
| LSC-R | 0.5 | 2.9 | 1.70 | 0.67 | 2.3 | 0.21 | – |
| CO-R | 0.6 | 2.7 | 1.96 | 0.57 | 2.3 | 0.13 | – |
| Ratios | |||||||
| ASCh/w | 72 | 104 | 88.1 | 7.4 | 87 | 4.6 | ns |
| PSCh/w | 83 | 126 | 109.6 | 9.1 | 107 | 7.6 | ns |
| LSCh/w | 73 | 113 | 88.9 | 8.9 | 89 | 7.0 | – |
| COh/w | 93 | 152 | 134.3 | 12.3 | 136 | 8.6 | ns |
| Angles (°)† | |||||||
| Labyrinth | |||||||
| ASC-tor | −5 | 21 | 6.5 | 7.4 | 16 | 5.3 | – |
| PSC-tor | −13 | 8 | −1.0 | 4.6 | −9 | 5.4 | – |
| LSC-tor | 2 | 26 | 14.1 | 5.7 | 4 | 4.1 | *** |
| ASCm<PSCm | 81 | 113 | 98.1 | 6.0 | 104 | 5.2 | – |
| LSCt<VSC | 98 | 121 | 112.1 | 5.6 | 112 | 5.0 | ns |
| COt<VSC | 105 | 147 | 117.3 | 8.6 | 116 | 4.9 | – |
| CCR<LSCm | 105 | 127 | 117.7 | 5.4 | 121 | 4.0 | ** |
| APA<LSCm | 15 | 54 | 32.3 | 7.9 | 41 | 4.7 | – |
| COs<LSCm | 32 | 66 | 48.4 | 8.8 | 59 | 5.1 | – |
| Labyrintho-midline | |||||||
| ASCm<SG | 20 | 49 | 39.8 | 5 | 36 | 4.9 | *** |
| ASCs<SG | 31 | 55 | 45.8 | 4.5 | 45 | 5.3 | ns |
| ASCi<SG | 23 | 50 | 39.2 | 6.5 | 29 | 4.7 | – |
| PSCm<SG | 121 | 153 | 137.9 | 6.6 | 139 | 5.4 | – |
| PSCs<SG | 125 | 146 | 133.8 | 4.1 | 127 | 5.7 | *** |
| PSCi<SG | 124 | 150 | 134.8 | 6.5 | 136 | 5.1 | – |
| LSCt<SG | 92 | 126 | 111.0 | 7.4 | 110 | 5.7 | – |
| COt<SG | 105 | 128 | 116.1 | 5.7 | 113 | 5.4 | – |
| Labyrintho-cranial | |||||||
| LSCm<S-Fc | 2 | −44 | −22.1 | 12.3 | −3 | 5.9 | – |
| APA<S-Fc | −37 | −85 | −54.4 | 9.6 | −44 | 6.8 | – |
| COs<S-Fc | −55 | −95 | −70.5 | 9.5 | −63 | 6.7 | – |
| CCR<S-Fc | −115 | −162 | −139.7 | 13.0 | −124 | 6.5 | – |
| LSCm<Ba-S | 15 | 39 | 26.2 | 6.3 | 39 | 6.1 | – |
| APA<Ba-S | 4 | −33 | −6.1 | 6.3 | −1 | 6.0 | *** |
| COs<Ba-S | −12 | −44 | −22.2 | 6.4 | −20 | 6.3 | ns |
| CCR<Ba-S | −79 | −105 | −91.4 | 7.3 | −82 | 5.5 | – |
| Basicranial | |||||||
| CBA | 116 | 147 | 131.6 | 7.3 | 137 | 4.9 | – |
| PPip<SG | 145 | 165 | 154.6 | 5.6 | 125 | 4.4 | – |
Angle classification: ASC-tor positive when ASCs is more coronally orientated than ASCi; PSC-tor positive when PSCs is more sagittally orientated than PSCi; the 5th & 6th labyrinth angles open anterolaterally whilst the last three open anterior-superiorly; all labyrintho-midline angles open anterolaterally; all labyrintho-cranial angles open anterosuperiorly, and are positive when the basicranial line segment (e.g. S-Fc) is anterosuperiorly to the labyrinth line segment (e.g. LSCm).
Adult values from Spoor (1993), Spoor & Zonneveld (1998), and newly calculated (n = 53 for angles of labyrinth, n = 50 for angles to SG, and n = 48 for angles to midline cranial base). The signs of labyrintho-cranial angles reported by Spoor (1993) were changed according to the conventions set by Spoor & Zonneveld (1998).
For those variables not correlated with EGA (Table 3) significant difference from the adult mean is indicated by * P ≤ 0.05, ** P ≤ 0.01, *** P ≤ 0.001; ns, not significantly different.