Page 185 - كتاب تمريض نسا الاكتروني

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3- Rupture of the membranes and flow of the amniotic fluid. Normally this occurs when
the cervix is fully dilated, however, it may occur early in labor in the first stage or
even before the start of labor( premature rupture of membranes). It may not occur at
all and the fetus is delivered inside the intact amniotic sac.

5- Full dilatation of the cervix: When it is fully dilated, it is 4 inches or 10cm. in
diameter and can admit 5 fingers (this is the sure sign).

 The Mechanism of Normal Labor:

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.

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