maternal pelvis and fetal skull

Maternal bony pelvis and fetal head
Objectives of this lecture
1- Introduction to normal labour and vaginal delivery passages, passenger, and power.
2- The student should know the types of female pelvis.
3- understand the importance of the dimensions of the bony pelvis of the pregnant woman in determining the progress of labour and the mode of delivery.
4- What are the methods for assessment of pelvic dimensions.
5- Know the dimensions of the fetal skull.
6- Understand how the attitude of the fetal head effect these dimensions.

Labour can be defined as the process by which regular painful contractions bring about effacement and dilatation of the cervix and descent of the presenting part, leading to expulsion of the fetus and the placenta from the mother.

Pelvic shapes (types)We have 4 types or shapes of the bony pelvis and these are: the gynecoid, android, anthropoid, and finally the platypelloid.

Pelvic diameters:These represent the space available for the fetal head when it passes through the pelvis during labour
1- the obstetric conjugate of the pelvic inlet: 11 cm
2- the bispinous diameter: 10.5 cm in the midcavity.
3- the bituberous diameter 11 cm in the pelvic outlet
4- the curve and length of the sacrum
5- and finally the subpubic angle