Page 59 - 33Elctronic Book (3) Normal Labor
P. 59
I- Cervical Dilatation
It is due to contraction and retraction of the uterus, which push the head or bag of
forewaters through the cervix. In primigravida, the cervix dilates from above
downwards. The internal os dilates at first, then the cervical canal is taken up or effaced
and finally the external os starts to dilate because it muscle fibers are still intact and
resist dilatation. In multigravida, dilation of the internal os, taking up of the cervix and
dilatation of the external os occur together at the same time.
Note: Effacement means the portio vaginalis of the cervix becomes short and thin.
II-Expulsion of the Fetus
A- Delivery of the Head: The following movements occur in the head during its
delivery:
1- Descent. 2- Engagement.
3- Increased flexion. 4- Internal rotation.
5- Extension. 6-Restitution.
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