Presenting diameter of full flexed head:
a) Suboccipito-bregmatic diameter
b) Suboccipito-frontal diameter
c) Occipito-frontal diameter
d) Occipito-posterior position
Correct Answer - A
Ans. A. Suboccipito-bregmatic diameter
Suboccipito-bregmatic diameter :
The diameter is from suboccipital region to centre of the bregma.
Diameter = 9.5 cm
Fetal head circumference is smallest (32 cm )
Head well flexed
Flexed vertex presentation
Suboccipito-frontal diameter :
Diameter calculated from prominence at mid frontal bone to the
under-surface of the occipital bone where it joins neck
The diameter is 10.5 cm
Vertex is partially deflexed.
Results in occipito-posterior position.
Occipito-frontal diameter :
Diameter extends from the prominent point of mid-frontal bone to the
most prominent point of occipital bone
The diameter = 11.5 cm
Fetal head circumference ~ 34.5 cm
Vertex is deflexed
Associated with Direct occipito- posterior position.
Occipito-posterior position :
It is a vertex presentation in which the occiput is placed posteriorly .