Anterior posterior diameter of skull
Transverse diameter of skull
|
Antero posterior diameter |
Measurement (cm) |
Presenting part |
Attitude of fetal head |
|
Occipito frontal (OF) |
11.5 |
Vertex |
Marked deflexion |
|
Sub occipito frontal (SOF) |
10 |
Vertex |
Incomplete flexion |
|
Sub occipito bregmatic (SOB) |
9.5 |
Vertex |
Complete flexion |
|
Submento bregmatic (SMB) |
9.5 |
Face |
Complete extension |
|
Submento vertical (SMV) |
11.5 |
Face |
Incomplete extension |
|
Mento vertical (MV) |
14 |
Brow |
Partial extension |
Mnemonic: “Vertex presentation” is found in all diameters whose names contain the word "occipito."
|
Transverse diameter |
Measurement (cm) |
|
Biparietal |
9.5 cm |
|
Super sub parietal |
8.5 cm |
|
Bitemporal |
8 cm |
|
Bimastoid |
7.5 cm |